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Research ArticleThe Mechanical Properties of a Novel STMR Damper Based onMagnetorheological Silly Putty
Xiao-Guo Lin12 Fei Guo3 Cheng-Bin Du 1 and Guo-Jun Yu4
1Department of Engineering Mechanics Hohai University Nanjing 211100 China2School of Civil and Transportation Engineering Ningbo University of Technology Ningbo 315211 China3MCC Huatian Engineering amp Technology Corporation Nanjing 210019 China4Faculty of Civil Engineering and Mechanics Jiangsu University Zhenjiang 212013 China
Correspondence should be addressed to Cheng-Bin Du cbduhhueducn
Received 6 February 2018 Accepted 10 April 2018 Published 25 June 2018
Academic Editor Kestutys Baltakys
Copyright copy 2018 Xiao-Guo Lin et al +is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
A novel shear thickening magnetorheological (STMR) damper with both speed locking and semiactive controlling properties wasdesigned and fabricated based on multifunctional smart composite materials which was defined as magnetorheological Silly Putty(MRSP)+e rate sensitive property and magnetorheological effect of MRSP samples were analyzed by using a rheometer to selectthe best filler for the STMR damper +e mechanical properties of the STMR damper were investigated through slow fast anddynamic experiments +e experimental results indicate that the STMR damper exhibits an obvious rate sensitive characteristicand semiactive control property On one hand when the STMR damper is simulated fast enough it can realize the ldquospeed switchrdquofunction which enables it to instantly lock up and act as a shock transmission unit (STU) On the other hand when the STMRdamper is applied with current the damping force can be adjusted by magnetic field strength to realize its semiactive controllingproperty In addition a multiparameter and symmetry model was established to describe the dynamic hysteretic behavior of theSTMR damper which is consistent with the experimental data
1 Introduction
Magnetorheological Silly Putty (MRSP) is a smart multi-functional composite prepared by dispersing soft magneticparticles into a Silly Putty matrix with shear stiffeningproperty [1] +is new kind of smart material is the solid stateof the magnetorheological shear thickening fluid (MRSTF)proposed by Zhang et al and Peng et al [2 3] SubsequentlyWang et al [4 5] first developed a magnetically responsiveshear-stiffening gel with excellent shear stiffening perfor-mance andmagnetorheological effect+is novelmagneticallyresponsive shear-stiffening gel can provide credible tunabilitywith external stimuli
At this stage the vibration damper based on a singlemagnetorheological material requires an external magneticfield which belongs to the active device Magnetorheologicalmaterials are widely used in all kinds of MR dampers and thetechnology is relatively mature Lord Company of USA and
BASF Company of Germany have developed many com-mercialized MR dampers For example the RD-1005-type MRdamper produced by Lord Company is the earliest applicationof the international commercializedMR damper with dampingforce over 2200N [6] MR dampers designed for large civilengineering structures show greater structure size and dampingforce output Qu et al developed a full-scale MR damperoutput of up to 500 kN carried out a study on the key tech-nologies of the leakproof design of themagnetic field and built-in butterfly spring and finally applied the full size MR damperto a highway railway cable-stayed bridge with semiactive vi-bration control [7ndash10] Yu et al developed the self-decoupledmagnetorheological (SDMR) damper which produced thelargest output of 360 kN +e displacement decouplingmechanism was set up in the damper and permanent magnetswere arranged to provide the function of self-protection +eSDMR damper was mainly applied to the semiactive vibrationcontrol of frame and grid structures [11ndash14]
HindawiAdvances in Materials Science and EngineeringVolume 2018 Article ID 2681461 15 pageshttpsdoiorg10115520182681461
+e single shear thickening material is used as energydissipation fillers for small passive ST dampers Zhang et aldeveloped a speed-driven damper based on the shearthickening fluid and studied the dynamic performance of theST damper through both experiment and theory methods[15]+ese results confirm that the STdamper presents higherstiffness and damping at high-speed dynamic loading thanthose at low-speed loading and absorbs more energy Zhouet al developed a double-out rod-type ST damper filled byshear thickening fluid of a high-concentration polystyrene-ethyl acrylate nanometer particle suspension +e dynamicalexperiment results reveal that with the increase in excitationfrequency the storage modulus and energy dissipationmodulus rapidly increase and the output of the ST damperdramatically boosts exhibiting great absorption and energydissipation capacity the maximum energy dissipationmodulus reached up to 21 kPa [16] +e most common ap-plication of shear thickening materials in civil engineeringstructures is the shock transmission unit (STU) which isa device resembling a speed switch It is basically approxi-mating to a general damper in appearance and internalstructure which is composed of a piston and cylinder andregarded as a special damper Silly Putty has becomea promising material for the special damper of STU which iswidely used in the multispan bridge [17]
+e MR damper is the most mature energy dissipationdevice in the field of magnetorheological vibration dampingFrom the point of energy the principle of the work is tochange the energy spectrum of the vibration sourcersquos ex-citation to the system and reduce the passed energy tosuppress the vibration However in the face of huge in-centive loads the vibration damping which the MR damperdepends on does not slow down the deformation or evendestruction of civil engineering structures due to insufficientstiffness besides the mechanism of damping is relativelysimple In addition these MR dampers all belong to activedevices whichmeans that in the event of a circuit failure thatcannot be controlled by a magnetic field the damper losesthe significance of the semiactive vibration control +ecurrent solutions include setting a permanent magnet tomake the magnetorheological fluid in the MR damperproduce certain yield strength but the scheme makes thedesign of the damper more complex Furthermore com-monly used permanent magnets are made of NdFeBmaterialwith strong temperature instability meaning that the higherthe temperature the faster the demagnetization +e shearthickening material is mainly used in caging devices in-cluding all kinds of speed locking devices in order to im-prove the overall stiffness of the structure and achieve thepurpose of seismic resistance and vibration reduction At themoment researchers of the world only focus on the study ofthe mechanisms of magnetorheological damping and shearthickening damping respectively and there is no in-tersection between each other However there are no rel-evant studies that combine the characteristics of two kinds ofintelligent materials as a whole to explore new intelligentdampers with double vibration damping mechanisms
In this work a novel shear thickening magneto-rheological (STMR) damper was designed and fabricated
based onMRSPs Compared with traditionalMR dampers theSTMR damper not only exhibited controllable characteristicsof damping force under the adjustment of the magnetic fieldbut also provided a ldquolockingrdquo function under an unexpectedsudden rare load which was more suitable for the vibrationcontrol of large civil engineering structures In order to verifythe dual vibration damping characteristics of the STMRdamper slow fast and dynamic mechanical property ex-periments were carried out Finally a multiparameter andsymmetry model was established and deduced to describe thedynamic hysteretic behavior of the STMR damper
2 Experimental Section of MRSPs
21 Materials +e Dow Corning 3179 dilatant compoundwhich was purchased from Dow Corning Co Ltd was usedas the Silly Putty matrix +e composition of the Silly Puttymatrix is outlined in Table 1 Polydimethylsiloxane (PDMS)as a commonly used organic silicon material is the majorconstituent of the composition +e soft magnetic particles ofthe carbonyl iron (CI) with an average size of 35 μm werepurchased from Jiangsu Tianyi Ultra-fine metal powder CoLtd (Xuyi China)
22 Preparation and Testing of MRSPs +e dilatant com-pound as matrix and the different volume fractions of CI asfillers were homogeneously mixed using a two-roll mill(Nantong Hailite Rubber Machinery Inc China XK-160model) at room temperature For the mechanical mixingmethod up to six different volume fractions were consideredfor the present study 0 698 1011 1584 2080 and 2729+e prepared samples were marked as MRSP 0 MRSP 1MRSP 2 MRSP 3 MRSP 4 and MRSP 5 in sequence In thiswork the dynamic rheological properties of theMRSP sampleswere carried out using a commercial rheometer (Physica MCR302 Anton Paar Co Austria) During the testing procedurea parallel plate PP20 with a diameter of approximately 20mmwas used and a gap of 1mmwasmaintained at all times At thesame time a controllable magnetic field was generated by anexternal coil Besides all the samples for the experiment weremaintained at an approximately same volume value+eMRSPsample and MCR 302 rheometer are displayed in Figure 1
3 Experimental Section of the STMR Damper
31 Designing of STMRDamper +e structure of the STMRdamper is shown in Figure 2 with its appearance
Table 1 Composition of the Silly Putty matrix
Composition Weight percentagePolydimethylsiloxane (PDMS) 65Silica 17+ixotrol 9Boric acid 4Glycerine 1Titanium dioxide 1Dimethyl cyclosiloxane 1
2 Advances in Materials Science and Engineering
approximating to a traditional MR damper mainly con-sisting of the main cylinder tube accessory cylinder tubeauxiliary cylinder main piston accessory piston and pistonrod +e filling material in the main cylinder exhibits high-MR effect while the inner filling material of the auxiliarycylinder presents a higher shear stiffening effect to improvethe overall safety reserve So both the main cylinder andauxiliary cylinder are combined together into a cooperativecylinder +e main piston and auxiliary piston are arrangedon the piston rod the main piston and piston rod areconnected with the method of a rigid threaded connectionand two circular excitation coils are detoured in two op-posite directions on the main piston Each of the two ex-citation coils connects one wire to the external power supplythrough the traverse channel and the power mode is in theparalleling way +e accessory piston is connected with thepiston rod through the butterfly spring and allows it to movealong the piston rod within the maximum compressionamount of the spring in order to realize the decouplingfunction +e filling materials in the main and auxiliarycylinders generate flow and deformation in their ownworking gaps
+e STMR damper mainly consists of the main cylindercontrolled by magnetorheology and the accessory cylinderwith displacement decoupling characteristic +is noveldamper not only maintains the performance of an adjustabledamping force by magnetic field but also possesses obviousrate sensitive characteristic which provides the function oflocking structure to disperse loading under high frequencyor impaction +e basic structural parameters of the STMRdamper are listed in Table 2
32 Testing of the STMRDamper +e physical object of theSTMR damper is displayed in Figure 3 +e energy dissi-pation of the STMR damper is mainly triggered by the flowand deformation of the filling materials +e rate sensitive
characteristic and magnetorheological effect of MRSPs arethe internal reasons for the damper to adapt to environ-mental incentives and directional intelligent controllabil-ity In order to verify the rate sensitivity and magneticcontrol characteristics of the STMR damper the me-chanical properties were investigated by the SDS-300electrohydraulic servostatic and dynamic testing ma-chine +e main contents of the testing included the fol-lowing (1) the influence of different rates on themechanical properties of the damper under slow and fastaxial tension conditions (2) the influence of differentfrequencies and different current excitations on the dy-namic hysteretic properties of the damper under large andsmall displacements+e installation of the testing machinefor the STMR damper is displayed in Figure 4 In the testingprocedure a current excitation with an adjustable DC-regulated power supply was adopted and the maximuminput current was 3 A In each experiment the pistoncarried on the reciprocating movement from the balanceposition which was mainly located in the middle positionbetween the main and accessory cylinder tubes In thedamper structure diagram the limit stroke of the pistonwas 65mm and in the present experiment of dynamicmechanical properties the amplitude of the large dis-placement was 55mm
4 Results and Discussion
41 Rate Sensitive Characteristic of MRSPs In the earlierresearch when there was no external magnetic field appliedthe soft magnetic particles of CI were evenly dispersed in theSilly Putty matrix to form isotropic viscoelastic materials[1] From this point the CI powder was considered asa general particle filling which played a role in strength-ening the matrix material +e larger the volume fraction ofthe CI particle is the greater the shear storage modulus ofthe sample becomes which is in consistent with the
(a) (b)
Figure 1 Preparation of (a) the MRSP sample and (b) the MCR 302 rheometer
Advances in Materials Science and Engineering 3
empirical formula (1) is formula explains the rule ofshear modulus varying with the volume fraction of rigidparticles randomly lled in the rubber matrix [18] eaddition of rigid particles leads to the decrease in internalmotion space within the matrix which further promotes theinteraction between the molecular chains Simultaneouslymore obvious obstacles are encountered in solving the
entanglement of the molecular chains which shows theescalation in shear storage modulus on a macroscopic pointof view [5]
Gran G0 1 + 25ϕ + 141ϕ2( ) (1)
where Gran refers to the shear modulus of composites lledwith rigid particle compositesG0 is the shear modulus of the
32
33
31
30
29
28
27
26
25
24
23
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1
2
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5
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8
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10
11
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13
14
15
Assembly drawing of STMR damper
SerialNumber Name Quantity
2Filling materials33
4Hexagon head bolt32
2Seal ring of type Yx31
1Front end cover30
8Screw29
1Main piston 328
1Main cylinder tube27
1Coil26
4Seal ring of type O25
2Magnetically isolatedcopper piece24
1Seal ring of type O23
2Seal ring of type O22
1Semiring sleeve21
2Semiring20
2Sleeve baffle19
2Seal ring of type O18
1Accessory cylinder tube17
4Pull rod bolt 216
1Back end cover15
1Auxiliary cylinder tube14
1Connecting cylinder cover 213
1Accessory piston 212
4Butterfly spring11
1Accessory piston sleeve10
1Accessory piston 19
1Connecting cylinder cover 18
1Main piston 27
1Coil sleeve6
1Main piston 15
4Seal ring of type O4
4Pull rod bolt 13
1Piston rod2
1Single earring for axial use1
Figure 2 Basic structure of the STMR damper
4 Advances in Materials Science and Engineering
matrix material without the filling of rigid particles and ϕmeans the volume fraction of rigid particles
Besides from the earlier research in order to comparethe shear stiffening degree of theMRSP samples the absoluteshear stiffening effect (ASTe) and relative shear stiffeningeffect (RSTe) are defined as the index of measurement [1] asshown specifically in the following formula
ASTe Gprimemax minusGprimemin
RSTe Gprimemax minusGprimemin
Gprimemintimes 100
(2)
where Gprimemax stands for the maximum shear storage modulusexcited by the loading frequency and Gprimemin refers to the initial
shear storage modulus When the angular frequency in-creases the MRSP samples exhibit an obvious rate sensitivecharacteristic and a sharply increased storage modulustogether with the demonstration that the sample ldquohardensrdquoFurthermore the higher the content of the CI powder is themore beneficial it is to the absolute shear stiffening effect ofthe material In earlier research [1] for the MRSP 5 sampleunder normal temperatures the absolute modulus change is06145MPa which equals to approximately twice the pureshear stiffening matrix MRSP 0 while the relative shearstiffening effect is 141264 which is far less than 7758421of the pure shear stiffening matrix MRSP 0
However under the condition of an external magneticfield the soft magnetic particles of the CI powder werearranged into chain-like ordered structures along the directionof the magnetic flux line in the interior of the shear stiffeningmatrix forming the anisotropic structure +e pure shearstiffening matrix MRSP 0 sample was not influenced by themagnetic field due to the absence of soft magnetic particlefillings Figure 5 illustrates the relationship between shearstorage modulus of the MRSP samples with different contentsof soft magnetic particles and the angular frequencies sepa-rately under different external magnetic fields in which theangular frequency is 1ndash100 rads with continuous change It isobserved from the diagram that with the strength of theexertedmagnetic field enhancing the shear storagemodulus ofthe sample increases as well For the MRSP 5 sample themaximum storage modulus after shear stiffening is approx-imately 05MPa under the condition of zero magnetic fieldNonetheless under the constant magnetic flux density of0627T the maximum storage modulus after shear stiffeningis up to 23MPa and the magneto-induced modulus causedby the magnetic field equals to approximately 18MPa Forthe transverse comparison between different samples whenthe content of the CI powder rises up the storage modulus atthe same magnetic flux density keeps an upward tendency+e maximum storage modulus of the MRSP 1 sample undera magnetic flux density of 0627T is 06MPa while theparticle mass fraction of MRSP 5 reaches twice as much asthat of MRSP 1 but the maximum modulus equals toapproximately four times as that of MRSP 1 On one hand nomatter how the soft magnetic particles are randomly filled orarranged in the matrix with a certain ordered structure underthe situation that the content of soft magnetic particles growsup the reinforcement effect of the material increases On theother hand previous studies expose that the higher the
Table 2 Main structure parameter of the STMR damperWorking gap of the main cylinder tube 2mm Working gap of the accessory cylinder 2mmExternal diameter of the main piston 156mm External diameter of the accessory piston 156mm
Wall thickness of steel tube of the main cylinder tube 15mm Wall thickness of steel tube of the accessory cylindertube 15mm
Pistonrsquos stroke limit of the main cylinder tube 65mm Pistonrsquos stroke limit of the accessory cylinder tube 65mmLength of working gap of the main cylinder tube 206mm Length of working gap of the accessory cylinder tube 117mmPistonrsquos number of windings of the main cylindertube 980 Effective stroke of decoupling spring 7mm
Diameter of piston rod 50mm Maximum power lt120WPistonrsquos current range of the main cylinder tube 0sim3A Designed damping force 300 kN
Figure 3 Entity of the STMR damper
Figure 4 +e experimental setup of the STMR damper
Advances in Materials Science and Engineering 5
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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+e single shear thickening material is used as energydissipation fillers for small passive ST dampers Zhang et aldeveloped a speed-driven damper based on the shearthickening fluid and studied the dynamic performance of theST damper through both experiment and theory methods[15]+ese results confirm that the STdamper presents higherstiffness and damping at high-speed dynamic loading thanthose at low-speed loading and absorbs more energy Zhouet al developed a double-out rod-type ST damper filled byshear thickening fluid of a high-concentration polystyrene-ethyl acrylate nanometer particle suspension +e dynamicalexperiment results reveal that with the increase in excitationfrequency the storage modulus and energy dissipationmodulus rapidly increase and the output of the ST damperdramatically boosts exhibiting great absorption and energydissipation capacity the maximum energy dissipationmodulus reached up to 21 kPa [16] +e most common ap-plication of shear thickening materials in civil engineeringstructures is the shock transmission unit (STU) which isa device resembling a speed switch It is basically approxi-mating to a general damper in appearance and internalstructure which is composed of a piston and cylinder andregarded as a special damper Silly Putty has becomea promising material for the special damper of STU which iswidely used in the multispan bridge [17]
+e MR damper is the most mature energy dissipationdevice in the field of magnetorheological vibration dampingFrom the point of energy the principle of the work is tochange the energy spectrum of the vibration sourcersquos ex-citation to the system and reduce the passed energy tosuppress the vibration However in the face of huge in-centive loads the vibration damping which the MR damperdepends on does not slow down the deformation or evendestruction of civil engineering structures due to insufficientstiffness besides the mechanism of damping is relativelysimple In addition these MR dampers all belong to activedevices whichmeans that in the event of a circuit failure thatcannot be controlled by a magnetic field the damper losesthe significance of the semiactive vibration control +ecurrent solutions include setting a permanent magnet tomake the magnetorheological fluid in the MR damperproduce certain yield strength but the scheme makes thedesign of the damper more complex Furthermore com-monly used permanent magnets are made of NdFeBmaterialwith strong temperature instability meaning that the higherthe temperature the faster the demagnetization +e shearthickening material is mainly used in caging devices in-cluding all kinds of speed locking devices in order to im-prove the overall stiffness of the structure and achieve thepurpose of seismic resistance and vibration reduction At themoment researchers of the world only focus on the study ofthe mechanisms of magnetorheological damping and shearthickening damping respectively and there is no in-tersection between each other However there are no rel-evant studies that combine the characteristics of two kinds ofintelligent materials as a whole to explore new intelligentdampers with double vibration damping mechanisms
In this work a novel shear thickening magneto-rheological (STMR) damper was designed and fabricated
based onMRSPs Compared with traditionalMR dampers theSTMR damper not only exhibited controllable characteristicsof damping force under the adjustment of the magnetic fieldbut also provided a ldquolockingrdquo function under an unexpectedsudden rare load which was more suitable for the vibrationcontrol of large civil engineering structures In order to verifythe dual vibration damping characteristics of the STMRdamper slow fast and dynamic mechanical property ex-periments were carried out Finally a multiparameter andsymmetry model was established and deduced to describe thedynamic hysteretic behavior of the STMR damper
2 Experimental Section of MRSPs
21 Materials +e Dow Corning 3179 dilatant compoundwhich was purchased from Dow Corning Co Ltd was usedas the Silly Putty matrix +e composition of the Silly Puttymatrix is outlined in Table 1 Polydimethylsiloxane (PDMS)as a commonly used organic silicon material is the majorconstituent of the composition +e soft magnetic particles ofthe carbonyl iron (CI) with an average size of 35 μm werepurchased from Jiangsu Tianyi Ultra-fine metal powder CoLtd (Xuyi China)
22 Preparation and Testing of MRSPs +e dilatant com-pound as matrix and the different volume fractions of CI asfillers were homogeneously mixed using a two-roll mill(Nantong Hailite Rubber Machinery Inc China XK-160model) at room temperature For the mechanical mixingmethod up to six different volume fractions were consideredfor the present study 0 698 1011 1584 2080 and 2729+e prepared samples were marked as MRSP 0 MRSP 1MRSP 2 MRSP 3 MRSP 4 and MRSP 5 in sequence In thiswork the dynamic rheological properties of theMRSP sampleswere carried out using a commercial rheometer (Physica MCR302 Anton Paar Co Austria) During the testing procedurea parallel plate PP20 with a diameter of approximately 20mmwas used and a gap of 1mmwasmaintained at all times At thesame time a controllable magnetic field was generated by anexternal coil Besides all the samples for the experiment weremaintained at an approximately same volume value+eMRSPsample and MCR 302 rheometer are displayed in Figure 1
3 Experimental Section of the STMR Damper
31 Designing of STMRDamper +e structure of the STMRdamper is shown in Figure 2 with its appearance
Table 1 Composition of the Silly Putty matrix
Composition Weight percentagePolydimethylsiloxane (PDMS) 65Silica 17+ixotrol 9Boric acid 4Glycerine 1Titanium dioxide 1Dimethyl cyclosiloxane 1
2 Advances in Materials Science and Engineering
approximating to a traditional MR damper mainly con-sisting of the main cylinder tube accessory cylinder tubeauxiliary cylinder main piston accessory piston and pistonrod +e filling material in the main cylinder exhibits high-MR effect while the inner filling material of the auxiliarycylinder presents a higher shear stiffening effect to improvethe overall safety reserve So both the main cylinder andauxiliary cylinder are combined together into a cooperativecylinder +e main piston and auxiliary piston are arrangedon the piston rod the main piston and piston rod areconnected with the method of a rigid threaded connectionand two circular excitation coils are detoured in two op-posite directions on the main piston Each of the two ex-citation coils connects one wire to the external power supplythrough the traverse channel and the power mode is in theparalleling way +e accessory piston is connected with thepiston rod through the butterfly spring and allows it to movealong the piston rod within the maximum compressionamount of the spring in order to realize the decouplingfunction +e filling materials in the main and auxiliarycylinders generate flow and deformation in their ownworking gaps
+e STMR damper mainly consists of the main cylindercontrolled by magnetorheology and the accessory cylinderwith displacement decoupling characteristic +is noveldamper not only maintains the performance of an adjustabledamping force by magnetic field but also possesses obviousrate sensitive characteristic which provides the function oflocking structure to disperse loading under high frequencyor impaction +e basic structural parameters of the STMRdamper are listed in Table 2
32 Testing of the STMRDamper +e physical object of theSTMR damper is displayed in Figure 3 +e energy dissi-pation of the STMR damper is mainly triggered by the flowand deformation of the filling materials +e rate sensitive
characteristic and magnetorheological effect of MRSPs arethe internal reasons for the damper to adapt to environ-mental incentives and directional intelligent controllabil-ity In order to verify the rate sensitivity and magneticcontrol characteristics of the STMR damper the me-chanical properties were investigated by the SDS-300electrohydraulic servostatic and dynamic testing ma-chine +e main contents of the testing included the fol-lowing (1) the influence of different rates on themechanical properties of the damper under slow and fastaxial tension conditions (2) the influence of differentfrequencies and different current excitations on the dy-namic hysteretic properties of the damper under large andsmall displacements+e installation of the testing machinefor the STMR damper is displayed in Figure 4 In the testingprocedure a current excitation with an adjustable DC-regulated power supply was adopted and the maximuminput current was 3 A In each experiment the pistoncarried on the reciprocating movement from the balanceposition which was mainly located in the middle positionbetween the main and accessory cylinder tubes In thedamper structure diagram the limit stroke of the pistonwas 65mm and in the present experiment of dynamicmechanical properties the amplitude of the large dis-placement was 55mm
4 Results and Discussion
41 Rate Sensitive Characteristic of MRSPs In the earlierresearch when there was no external magnetic field appliedthe soft magnetic particles of CI were evenly dispersed in theSilly Putty matrix to form isotropic viscoelastic materials[1] From this point the CI powder was considered asa general particle filling which played a role in strength-ening the matrix material +e larger the volume fraction ofthe CI particle is the greater the shear storage modulus ofthe sample becomes which is in consistent with the
(a) (b)
Figure 1 Preparation of (a) the MRSP sample and (b) the MCR 302 rheometer
Advances in Materials Science and Engineering 3
empirical formula (1) is formula explains the rule ofshear modulus varying with the volume fraction of rigidparticles randomly lled in the rubber matrix [18] eaddition of rigid particles leads to the decrease in internalmotion space within the matrix which further promotes theinteraction between the molecular chains Simultaneouslymore obvious obstacles are encountered in solving the
entanglement of the molecular chains which shows theescalation in shear storage modulus on a macroscopic pointof view [5]
Gran G0 1 + 25ϕ + 141ϕ2( ) (1)
where Gran refers to the shear modulus of composites lledwith rigid particle compositesG0 is the shear modulus of the
32
33
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Assembly drawing of STMR damper
SerialNumber Name Quantity
2Filling materials33
4Hexagon head bolt32
2Seal ring of type Yx31
1Front end cover30
8Screw29
1Main piston 328
1Main cylinder tube27
1Coil26
4Seal ring of type O25
2Magnetically isolatedcopper piece24
1Seal ring of type O23
2Seal ring of type O22
1Semiring sleeve21
2Semiring20
2Sleeve baffle19
2Seal ring of type O18
1Accessory cylinder tube17
4Pull rod bolt 216
1Back end cover15
1Auxiliary cylinder tube14
1Connecting cylinder cover 213
1Accessory piston 212
4Butterfly spring11
1Accessory piston sleeve10
1Accessory piston 19
1Connecting cylinder cover 18
1Main piston 27
1Coil sleeve6
1Main piston 15
4Seal ring of type O4
4Pull rod bolt 13
1Piston rod2
1Single earring for axial use1
Figure 2 Basic structure of the STMR damper
4 Advances in Materials Science and Engineering
matrix material without the filling of rigid particles and ϕmeans the volume fraction of rigid particles
Besides from the earlier research in order to comparethe shear stiffening degree of theMRSP samples the absoluteshear stiffening effect (ASTe) and relative shear stiffeningeffect (RSTe) are defined as the index of measurement [1] asshown specifically in the following formula
ASTe Gprimemax minusGprimemin
RSTe Gprimemax minusGprimemin
Gprimemintimes 100
(2)
where Gprimemax stands for the maximum shear storage modulusexcited by the loading frequency and Gprimemin refers to the initial
shear storage modulus When the angular frequency in-creases the MRSP samples exhibit an obvious rate sensitivecharacteristic and a sharply increased storage modulustogether with the demonstration that the sample ldquohardensrdquoFurthermore the higher the content of the CI powder is themore beneficial it is to the absolute shear stiffening effect ofthe material In earlier research [1] for the MRSP 5 sampleunder normal temperatures the absolute modulus change is06145MPa which equals to approximately twice the pureshear stiffening matrix MRSP 0 while the relative shearstiffening effect is 141264 which is far less than 7758421of the pure shear stiffening matrix MRSP 0
However under the condition of an external magneticfield the soft magnetic particles of the CI powder werearranged into chain-like ordered structures along the directionof the magnetic flux line in the interior of the shear stiffeningmatrix forming the anisotropic structure +e pure shearstiffening matrix MRSP 0 sample was not influenced by themagnetic field due to the absence of soft magnetic particlefillings Figure 5 illustrates the relationship between shearstorage modulus of the MRSP samples with different contentsof soft magnetic particles and the angular frequencies sepa-rately under different external magnetic fields in which theangular frequency is 1ndash100 rads with continuous change It isobserved from the diagram that with the strength of theexertedmagnetic field enhancing the shear storagemodulus ofthe sample increases as well For the MRSP 5 sample themaximum storage modulus after shear stiffening is approx-imately 05MPa under the condition of zero magnetic fieldNonetheless under the constant magnetic flux density of0627T the maximum storage modulus after shear stiffeningis up to 23MPa and the magneto-induced modulus causedby the magnetic field equals to approximately 18MPa Forthe transverse comparison between different samples whenthe content of the CI powder rises up the storage modulus atthe same magnetic flux density keeps an upward tendency+e maximum storage modulus of the MRSP 1 sample undera magnetic flux density of 0627T is 06MPa while theparticle mass fraction of MRSP 5 reaches twice as much asthat of MRSP 1 but the maximum modulus equals toapproximately four times as that of MRSP 1 On one hand nomatter how the soft magnetic particles are randomly filled orarranged in the matrix with a certain ordered structure underthe situation that the content of soft magnetic particles growsup the reinforcement effect of the material increases On theother hand previous studies expose that the higher the
Table 2 Main structure parameter of the STMR damperWorking gap of the main cylinder tube 2mm Working gap of the accessory cylinder 2mmExternal diameter of the main piston 156mm External diameter of the accessory piston 156mm
Wall thickness of steel tube of the main cylinder tube 15mm Wall thickness of steel tube of the accessory cylindertube 15mm
Pistonrsquos stroke limit of the main cylinder tube 65mm Pistonrsquos stroke limit of the accessory cylinder tube 65mmLength of working gap of the main cylinder tube 206mm Length of working gap of the accessory cylinder tube 117mmPistonrsquos number of windings of the main cylindertube 980 Effective stroke of decoupling spring 7mm
Diameter of piston rod 50mm Maximum power lt120WPistonrsquos current range of the main cylinder tube 0sim3A Designed damping force 300 kN
Figure 3 Entity of the STMR damper
Figure 4 +e experimental setup of the STMR damper
Advances in Materials Science and Engineering 5
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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Hindawiwwwhindawicom Volume 2018
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Submit your manuscripts atwwwhindawicom
approximating to a traditional MR damper mainly con-sisting of the main cylinder tube accessory cylinder tubeauxiliary cylinder main piston accessory piston and pistonrod +e filling material in the main cylinder exhibits high-MR effect while the inner filling material of the auxiliarycylinder presents a higher shear stiffening effect to improvethe overall safety reserve So both the main cylinder andauxiliary cylinder are combined together into a cooperativecylinder +e main piston and auxiliary piston are arrangedon the piston rod the main piston and piston rod areconnected with the method of a rigid threaded connectionand two circular excitation coils are detoured in two op-posite directions on the main piston Each of the two ex-citation coils connects one wire to the external power supplythrough the traverse channel and the power mode is in theparalleling way +e accessory piston is connected with thepiston rod through the butterfly spring and allows it to movealong the piston rod within the maximum compressionamount of the spring in order to realize the decouplingfunction +e filling materials in the main and auxiliarycylinders generate flow and deformation in their ownworking gaps
+e STMR damper mainly consists of the main cylindercontrolled by magnetorheology and the accessory cylinderwith displacement decoupling characteristic +is noveldamper not only maintains the performance of an adjustabledamping force by magnetic field but also possesses obviousrate sensitive characteristic which provides the function oflocking structure to disperse loading under high frequencyor impaction +e basic structural parameters of the STMRdamper are listed in Table 2
32 Testing of the STMRDamper +e physical object of theSTMR damper is displayed in Figure 3 +e energy dissi-pation of the STMR damper is mainly triggered by the flowand deformation of the filling materials +e rate sensitive
characteristic and magnetorheological effect of MRSPs arethe internal reasons for the damper to adapt to environ-mental incentives and directional intelligent controllabil-ity In order to verify the rate sensitivity and magneticcontrol characteristics of the STMR damper the me-chanical properties were investigated by the SDS-300electrohydraulic servostatic and dynamic testing ma-chine +e main contents of the testing included the fol-lowing (1) the influence of different rates on themechanical properties of the damper under slow and fastaxial tension conditions (2) the influence of differentfrequencies and different current excitations on the dy-namic hysteretic properties of the damper under large andsmall displacements+e installation of the testing machinefor the STMR damper is displayed in Figure 4 In the testingprocedure a current excitation with an adjustable DC-regulated power supply was adopted and the maximuminput current was 3 A In each experiment the pistoncarried on the reciprocating movement from the balanceposition which was mainly located in the middle positionbetween the main and accessory cylinder tubes In thedamper structure diagram the limit stroke of the pistonwas 65mm and in the present experiment of dynamicmechanical properties the amplitude of the large dis-placement was 55mm
4 Results and Discussion
41 Rate Sensitive Characteristic of MRSPs In the earlierresearch when there was no external magnetic field appliedthe soft magnetic particles of CI were evenly dispersed in theSilly Putty matrix to form isotropic viscoelastic materials[1] From this point the CI powder was considered asa general particle filling which played a role in strength-ening the matrix material +e larger the volume fraction ofthe CI particle is the greater the shear storage modulus ofthe sample becomes which is in consistent with the
(a) (b)
Figure 1 Preparation of (a) the MRSP sample and (b) the MCR 302 rheometer
Advances in Materials Science and Engineering 3
empirical formula (1) is formula explains the rule ofshear modulus varying with the volume fraction of rigidparticles randomly lled in the rubber matrix [18] eaddition of rigid particles leads to the decrease in internalmotion space within the matrix which further promotes theinteraction between the molecular chains Simultaneouslymore obvious obstacles are encountered in solving the
entanglement of the molecular chains which shows theescalation in shear storage modulus on a macroscopic pointof view [5]
Gran G0 1 + 25ϕ + 141ϕ2( ) (1)
where Gran refers to the shear modulus of composites lledwith rigid particle compositesG0 is the shear modulus of the
32
33
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Assembly drawing of STMR damper
SerialNumber Name Quantity
2Filling materials33
4Hexagon head bolt32
2Seal ring of type Yx31
1Front end cover30
8Screw29
1Main piston 328
1Main cylinder tube27
1Coil26
4Seal ring of type O25
2Magnetically isolatedcopper piece24
1Seal ring of type O23
2Seal ring of type O22
1Semiring sleeve21
2Semiring20
2Sleeve baffle19
2Seal ring of type O18
1Accessory cylinder tube17
4Pull rod bolt 216
1Back end cover15
1Auxiliary cylinder tube14
1Connecting cylinder cover 213
1Accessory piston 212
4Butterfly spring11
1Accessory piston sleeve10
1Accessory piston 19
1Connecting cylinder cover 18
1Main piston 27
1Coil sleeve6
1Main piston 15
4Seal ring of type O4
4Pull rod bolt 13
1Piston rod2
1Single earring for axial use1
Figure 2 Basic structure of the STMR damper
4 Advances in Materials Science and Engineering
matrix material without the filling of rigid particles and ϕmeans the volume fraction of rigid particles
Besides from the earlier research in order to comparethe shear stiffening degree of theMRSP samples the absoluteshear stiffening effect (ASTe) and relative shear stiffeningeffect (RSTe) are defined as the index of measurement [1] asshown specifically in the following formula
ASTe Gprimemax minusGprimemin
RSTe Gprimemax minusGprimemin
Gprimemintimes 100
(2)
where Gprimemax stands for the maximum shear storage modulusexcited by the loading frequency and Gprimemin refers to the initial
shear storage modulus When the angular frequency in-creases the MRSP samples exhibit an obvious rate sensitivecharacteristic and a sharply increased storage modulustogether with the demonstration that the sample ldquohardensrdquoFurthermore the higher the content of the CI powder is themore beneficial it is to the absolute shear stiffening effect ofthe material In earlier research [1] for the MRSP 5 sampleunder normal temperatures the absolute modulus change is06145MPa which equals to approximately twice the pureshear stiffening matrix MRSP 0 while the relative shearstiffening effect is 141264 which is far less than 7758421of the pure shear stiffening matrix MRSP 0
However under the condition of an external magneticfield the soft magnetic particles of the CI powder werearranged into chain-like ordered structures along the directionof the magnetic flux line in the interior of the shear stiffeningmatrix forming the anisotropic structure +e pure shearstiffening matrix MRSP 0 sample was not influenced by themagnetic field due to the absence of soft magnetic particlefillings Figure 5 illustrates the relationship between shearstorage modulus of the MRSP samples with different contentsof soft magnetic particles and the angular frequencies sepa-rately under different external magnetic fields in which theangular frequency is 1ndash100 rads with continuous change It isobserved from the diagram that with the strength of theexertedmagnetic field enhancing the shear storagemodulus ofthe sample increases as well For the MRSP 5 sample themaximum storage modulus after shear stiffening is approx-imately 05MPa under the condition of zero magnetic fieldNonetheless under the constant magnetic flux density of0627T the maximum storage modulus after shear stiffeningis up to 23MPa and the magneto-induced modulus causedby the magnetic field equals to approximately 18MPa Forthe transverse comparison between different samples whenthe content of the CI powder rises up the storage modulus atthe same magnetic flux density keeps an upward tendency+e maximum storage modulus of the MRSP 1 sample undera magnetic flux density of 0627T is 06MPa while theparticle mass fraction of MRSP 5 reaches twice as much asthat of MRSP 1 but the maximum modulus equals toapproximately four times as that of MRSP 1 On one hand nomatter how the soft magnetic particles are randomly filled orarranged in the matrix with a certain ordered structure underthe situation that the content of soft magnetic particles growsup the reinforcement effect of the material increases On theother hand previous studies expose that the higher the
Table 2 Main structure parameter of the STMR damperWorking gap of the main cylinder tube 2mm Working gap of the accessory cylinder 2mmExternal diameter of the main piston 156mm External diameter of the accessory piston 156mm
Wall thickness of steel tube of the main cylinder tube 15mm Wall thickness of steel tube of the accessory cylindertube 15mm
Pistonrsquos stroke limit of the main cylinder tube 65mm Pistonrsquos stroke limit of the accessory cylinder tube 65mmLength of working gap of the main cylinder tube 206mm Length of working gap of the accessory cylinder tube 117mmPistonrsquos number of windings of the main cylindertube 980 Effective stroke of decoupling spring 7mm
Diameter of piston rod 50mm Maximum power lt120WPistonrsquos current range of the main cylinder tube 0sim3A Designed damping force 300 kN
Figure 3 Entity of the STMR damper
Figure 4 +e experimental setup of the STMR damper
Advances in Materials Science and Engineering 5
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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empirical formula (1) is formula explains the rule ofshear modulus varying with the volume fraction of rigidparticles randomly lled in the rubber matrix [18] eaddition of rigid particles leads to the decrease in internalmotion space within the matrix which further promotes theinteraction between the molecular chains Simultaneouslymore obvious obstacles are encountered in solving the
entanglement of the molecular chains which shows theescalation in shear storage modulus on a macroscopic pointof view [5]
Gran G0 1 + 25ϕ + 141ϕ2( ) (1)
where Gran refers to the shear modulus of composites lledwith rigid particle compositesG0 is the shear modulus of the
32
33
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Assembly drawing of STMR damper
SerialNumber Name Quantity
2Filling materials33
4Hexagon head bolt32
2Seal ring of type Yx31
1Front end cover30
8Screw29
1Main piston 328
1Main cylinder tube27
1Coil26
4Seal ring of type O25
2Magnetically isolatedcopper piece24
1Seal ring of type O23
2Seal ring of type O22
1Semiring sleeve21
2Semiring20
2Sleeve baffle19
2Seal ring of type O18
1Accessory cylinder tube17
4Pull rod bolt 216
1Back end cover15
1Auxiliary cylinder tube14
1Connecting cylinder cover 213
1Accessory piston 212
4Butterfly spring11
1Accessory piston sleeve10
1Accessory piston 19
1Connecting cylinder cover 18
1Main piston 27
1Coil sleeve6
1Main piston 15
4Seal ring of type O4
4Pull rod bolt 13
1Piston rod2
1Single earring for axial use1
Figure 2 Basic structure of the STMR damper
4 Advances in Materials Science and Engineering
matrix material without the filling of rigid particles and ϕmeans the volume fraction of rigid particles
Besides from the earlier research in order to comparethe shear stiffening degree of theMRSP samples the absoluteshear stiffening effect (ASTe) and relative shear stiffeningeffect (RSTe) are defined as the index of measurement [1] asshown specifically in the following formula
ASTe Gprimemax minusGprimemin
RSTe Gprimemax minusGprimemin
Gprimemintimes 100
(2)
where Gprimemax stands for the maximum shear storage modulusexcited by the loading frequency and Gprimemin refers to the initial
shear storage modulus When the angular frequency in-creases the MRSP samples exhibit an obvious rate sensitivecharacteristic and a sharply increased storage modulustogether with the demonstration that the sample ldquohardensrdquoFurthermore the higher the content of the CI powder is themore beneficial it is to the absolute shear stiffening effect ofthe material In earlier research [1] for the MRSP 5 sampleunder normal temperatures the absolute modulus change is06145MPa which equals to approximately twice the pureshear stiffening matrix MRSP 0 while the relative shearstiffening effect is 141264 which is far less than 7758421of the pure shear stiffening matrix MRSP 0
However under the condition of an external magneticfield the soft magnetic particles of the CI powder werearranged into chain-like ordered structures along the directionof the magnetic flux line in the interior of the shear stiffeningmatrix forming the anisotropic structure +e pure shearstiffening matrix MRSP 0 sample was not influenced by themagnetic field due to the absence of soft magnetic particlefillings Figure 5 illustrates the relationship between shearstorage modulus of the MRSP samples with different contentsof soft magnetic particles and the angular frequencies sepa-rately under different external magnetic fields in which theangular frequency is 1ndash100 rads with continuous change It isobserved from the diagram that with the strength of theexertedmagnetic field enhancing the shear storagemodulus ofthe sample increases as well For the MRSP 5 sample themaximum storage modulus after shear stiffening is approx-imately 05MPa under the condition of zero magnetic fieldNonetheless under the constant magnetic flux density of0627T the maximum storage modulus after shear stiffeningis up to 23MPa and the magneto-induced modulus causedby the magnetic field equals to approximately 18MPa Forthe transverse comparison between different samples whenthe content of the CI powder rises up the storage modulus atthe same magnetic flux density keeps an upward tendency+e maximum storage modulus of the MRSP 1 sample undera magnetic flux density of 0627T is 06MPa while theparticle mass fraction of MRSP 5 reaches twice as much asthat of MRSP 1 but the maximum modulus equals toapproximately four times as that of MRSP 1 On one hand nomatter how the soft magnetic particles are randomly filled orarranged in the matrix with a certain ordered structure underthe situation that the content of soft magnetic particles growsup the reinforcement effect of the material increases On theother hand previous studies expose that the higher the
Table 2 Main structure parameter of the STMR damperWorking gap of the main cylinder tube 2mm Working gap of the accessory cylinder 2mmExternal diameter of the main piston 156mm External diameter of the accessory piston 156mm
Wall thickness of steel tube of the main cylinder tube 15mm Wall thickness of steel tube of the accessory cylindertube 15mm
Pistonrsquos stroke limit of the main cylinder tube 65mm Pistonrsquos stroke limit of the accessory cylinder tube 65mmLength of working gap of the main cylinder tube 206mm Length of working gap of the accessory cylinder tube 117mmPistonrsquos number of windings of the main cylindertube 980 Effective stroke of decoupling spring 7mm
Diameter of piston rod 50mm Maximum power lt120WPistonrsquos current range of the main cylinder tube 0sim3A Designed damping force 300 kN
Figure 3 Entity of the STMR damper
Figure 4 +e experimental setup of the STMR damper
Advances in Materials Science and Engineering 5
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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Hindawiwwwhindawicom Volume 2018
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ria
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Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
matrix material without the filling of rigid particles and ϕmeans the volume fraction of rigid particles
Besides from the earlier research in order to comparethe shear stiffening degree of theMRSP samples the absoluteshear stiffening effect (ASTe) and relative shear stiffeningeffect (RSTe) are defined as the index of measurement [1] asshown specifically in the following formula
ASTe Gprimemax minusGprimemin
RSTe Gprimemax minusGprimemin
Gprimemintimes 100
(2)
where Gprimemax stands for the maximum shear storage modulusexcited by the loading frequency and Gprimemin refers to the initial
shear storage modulus When the angular frequency in-creases the MRSP samples exhibit an obvious rate sensitivecharacteristic and a sharply increased storage modulustogether with the demonstration that the sample ldquohardensrdquoFurthermore the higher the content of the CI powder is themore beneficial it is to the absolute shear stiffening effect ofthe material In earlier research [1] for the MRSP 5 sampleunder normal temperatures the absolute modulus change is06145MPa which equals to approximately twice the pureshear stiffening matrix MRSP 0 while the relative shearstiffening effect is 141264 which is far less than 7758421of the pure shear stiffening matrix MRSP 0
However under the condition of an external magneticfield the soft magnetic particles of the CI powder werearranged into chain-like ordered structures along the directionof the magnetic flux line in the interior of the shear stiffeningmatrix forming the anisotropic structure +e pure shearstiffening matrix MRSP 0 sample was not influenced by themagnetic field due to the absence of soft magnetic particlefillings Figure 5 illustrates the relationship between shearstorage modulus of the MRSP samples with different contentsof soft magnetic particles and the angular frequencies sepa-rately under different external magnetic fields in which theangular frequency is 1ndash100 rads with continuous change It isobserved from the diagram that with the strength of theexertedmagnetic field enhancing the shear storagemodulus ofthe sample increases as well For the MRSP 5 sample themaximum storage modulus after shear stiffening is approx-imately 05MPa under the condition of zero magnetic fieldNonetheless under the constant magnetic flux density of0627T the maximum storage modulus after shear stiffeningis up to 23MPa and the magneto-induced modulus causedby the magnetic field equals to approximately 18MPa Forthe transverse comparison between different samples whenthe content of the CI powder rises up the storage modulus atthe same magnetic flux density keeps an upward tendency+e maximum storage modulus of the MRSP 1 sample undera magnetic flux density of 0627T is 06MPa while theparticle mass fraction of MRSP 5 reaches twice as much asthat of MRSP 1 but the maximum modulus equals toapproximately four times as that of MRSP 1 On one hand nomatter how the soft magnetic particles are randomly filled orarranged in the matrix with a certain ordered structure underthe situation that the content of soft magnetic particles growsup the reinforcement effect of the material increases On theother hand previous studies expose that the higher the
Table 2 Main structure parameter of the STMR damperWorking gap of the main cylinder tube 2mm Working gap of the accessory cylinder 2mmExternal diameter of the main piston 156mm External diameter of the accessory piston 156mm
Wall thickness of steel tube of the main cylinder tube 15mm Wall thickness of steel tube of the accessory cylindertube 15mm
Pistonrsquos stroke limit of the main cylinder tube 65mm Pistonrsquos stroke limit of the accessory cylinder tube 65mmLength of working gap of the main cylinder tube 206mm Length of working gap of the accessory cylinder tube 117mmPistonrsquos number of windings of the main cylindertube 980 Effective stroke of decoupling spring 7mm
Diameter of piston rod 50mm Maximum power lt120WPistonrsquos current range of the main cylinder tube 0sim3A Designed damping force 300 kN
Figure 3 Entity of the STMR damper
Figure 4 +e experimental setup of the STMR damper
Advances in Materials Science and Engineering 5
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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Submit your manuscripts atwwwhindawicom
06
05
04
03
02
01
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(a)
12
10
08
06
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(b)
0 20 40 60 80 100
14
16
18
12
10
08
04
02
00
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
Angular frequency ω (rads)
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(c)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(d)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
0 20 40 60 80 100Angular frequency ω (rads)
2624222018161412100806040200
0 T0102 T0211 T
0321 T0430 T
0533 T0627 T
(e)
Figure 5 e shear storage modulus of MRSP samples as a function of angular frequency at dierent magnetic ux densities (a) MRSP 1(b) MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
6 Advances in Materials Science and Engineering
volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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volume fraction of particles the denser the chain-like orderedstructures form under the same magnetic field conditionwhich leads to the increasing of themagneto-inducedmodulus
Similarly the ASTe and RSTe indexes are implementedto illustrate the influence of magnetic flux density on theshear stiffening effect of the MRSP samples and the rel-evant parameters are listed in Table 3 It is perceived thatfor samples with low content of soft magnetic particlessuch as MRSP 1 and MRSP 2 the magnetic flux density isconducive to the promotion of the shear stiffening effect ofthe MRSP samples +e greater the magnetic flux density isthe more superior the value of the ASTe becomes Forsamples with volume fraction of soft magnetic particle upto 15 such as MRSP 3 MRSP 4 and MRSP 5 the in-fluence of magnetic flux density on absolute shear stiffeningeffect is relatively complex With the increase of magneticflux density ASTe presents a tendency of falling down afterascending first which demonstrates that only under weakmagnetic field conditions (no more than 01 T) it becomesconducive to the absolute shear stiffening effect of highparticle content samples Besides with the increase of
magnetic flux density the initial shear storage modulus ofthe samples significantly intensifies while the relative shearstiffening effect of samples declines and the RSTe valuedecreases However for the transverse comparison betweendifferent samples under the zero magnetic field conditionsthe higher the particle content of the sample becomes thegreater the absolute shear stiffening effect it achieves whichis in line with the previous description As the intensity ofthe magnetic field increases for the samples with the higherparticle content the ASTe value becomes smaller Whenthe magnetic flux density is 0627 T the change in theabsolute modulus of MRSP 2 is 0729MPa Neverthelesswith the increase of particle content the ASTe value of thesample subsequently declines and in addition the absolutemodulus of MRSP 5 drops to only 022MPa Under zeromagnetic field condition the filling of soft magnetic par-ticles plays a certain positive role in the absolute moduluschange in the MRSP samples As the magnetic flux densityincreases the ordered structure of the soft magnetic par-ticles in the interior of the matrix becomes more complex+e larger the volume fraction is the closer the connections
Table 3 Gprimemax Gprimemin ASTe and RSTe of the MRSP samples
Samples Magnetic flux density B (T) Gprimemax (MPa) Gprimemin (MPa) ASTe (MPa) RSTe ()
MRSP 1
0 0287 000346 028354 8194800102 0349 001620 033280 2054320211 0480 006410 041590 648830321 0566 010900 045700 419270430 0603 013400 046900 3500533 0618 014400 047400 329170627 0627 015000 047700 318
MRSP 2
0 0309 000531 030369 5719210102 0383 003550 034750 978870211 0873 022900 064400 281220321 1060 037000 069000 186490430 1160 044000 072000 163640533 1190 045900 073100 159260627 1200 047100 072900 15478
MRSP 3
0 0411 00131 039790 3037400102 0924 02900 063400 218620211 1280 06690 061100 91330321 1500 09190 058100 63220430 1610 10400 057000 54810533 1670 10900 058000 53210627 1710 11300 058000 5133
MRSP 4
0 044 00228 041720 1829820102 124 0366 087400 238800211 190 119 071 59660321 214 159 055 34590430 224 177 047 26550533 231 186 045 24190627 231 192 039 2031
MRSP 5
0 051 00239 04861 2033890102 167 0814 08560 105160211 215 167 048 28740321 229 195 034 17440430 232 204 028 13730533 233 208 025 12020627 234 212 022 1038
Advances in Materials Science and Engineering 7
become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
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become between particles and particles and between chainand chain thereby providing partial support for themacroscopic shear modulus However the movement ofthe matrix molecular chains is greatly hindered due to thedecrease of internal motion space within the matrix Fromthe viscoelastic aspect it is not beneficial to the relaxationand rebalance process of the high molecular polymerwhich leads to the reduction of the absolute shear stiffeningeffect of the samples +erefore for the MRSP samples witha high content of soft magnetic particles in order to givefull play to the characteristic of shear stiffening the externalmagnetic field in its working environment should not betoo large
42 Magnetorheological Effect of MRSPs Under a continu-ously changing magnetic field the soft magnetic particles arerapidly magnetized into dipoles and are arranged into chain-like ordered structures within the interior of the matrix untilthe magnetic saturation is achieved Macroscopically thecontinuous variation of the shear modulus of the MRSPseventually reaches a steady state of saturation +e mag-netorheological effect determines the directional controlla-ble performance of theMRSPs which is usually measured bythe change of modulus Currently the research results in-dicated that the lower the loading frequency was the higherthe magnetorheological effect became and the more theconducive it was to the adjustment of the magnetic fieldHowever the loading frequency was higher the matrixmodulus of MRSP became larger the chain-like resistance ofsoft magnetic particles in the interior of the matrix becamegreater and the magnetorheological effect tended to belower [1] Figure 6 reveals the varied relationship betweenthe shear storage modulus and magnetic flux density ofdifferent samples under the conditions of different shearstrain low load frequency (ω1 rads) and magnetic fluxdensity continuous changing from 0 to 0894 T Corre-spondingly the larger the shear strain is the smaller thestorage modulus of the sample becomes As the magneticflux density enhances the shear storage modulus rapidlyincreases before 04 T and gradually tends to magneticsaturation after 04 T Likewise the absolute magneto-rheological effect (AMRe) and relative magnetorheologicaleffect (RMRe) are adopted as the indexes for the perfor-mance of magnetic field adjustment as shown in the fol-lowing equation
AMRe Gprimemax minusGprimemin
RMRe Gprimemax minusGprimemin
Gprimemintimes 100
(3)
where Gprimemax means the maximum shear storage moduluswhen reaching magnetic saturation while Gprimemin is the initialshear storage modulus under zero magnetic field +ecorrelated results of all the curves in Figure 6 which arecalculated according to (3) are listed in Table 4
For the transverse comparison of the samples withdifferent contents of soft magnetic particles the larger the
volume fraction of soft magnetic particles is the greater themagneto-induced modulus becomes and the more obviousthe absolute magnetorheological effect tends to be ForMRSP 5 with the highest particle content the magneto-induced modulus is up to 15MPa at the strain of 05 +erelative magnetorheological effect is mainly determined bythe initial shear storage modulus from which it can beobserved that for loading conditions at small strains of05 and 1 the relative magnetorheological effect pro-duced by the same sample varies with no obvious differencefrom each other +is is for the reason that within the strainof 1 each group of MRSP sample is in the linear vis-coelastic region which displays no obvious difference ofinitial modulus However when the strain continues toclimb up to 5 and 10 respectively the initial modulussharply decreases outside the linear viscoelastic region andin turn the magnetorheological effect becomes quite dif-ferent Besides the relative magnetorheological effect withstrain of 10 is higher than that with the strain of 5 Withthe increase in the content of CI powder the relativemagnetorheological effect tends to enhance When thestrain is 05 the relative magnetorheological effect ofMRSP 5 reaches 352 at most nevertheless if the shearstrain increases to 10 the relative magnetorheologicaleffect of MRSP 4 reaches as high as 617 and the adjustablerange of the magnetic field is relatively wide Consequentlyit is beneficial to obtain great magnetorheological effectwhen the volume fraction of the soft magnetic particle ishigh
43 Slow and Fast Mechanical Properties of the STMRDamper By comparing the rate sensitive characteristic andmagnetorheological effect of each MRSP samples the MRSP5 sample with high magnetorheological effect was finallyselected as the filling material in the main cylinder tube ofthe STMR damper Since there was no soft magnetic par-ticles filled in MRSP 0 sample due to its higher relative shearstiffening effect it was regarded as the fillingmaterials for theaccessory cylinder tube of the STMR damper For the STMRdamper with the locking function when the relative speedrate of the piston to the cylinder is slower than 1mms it isconsidered as a slow testing but when the speed rate is greaterthan 1mms it is regarded as a fast testing Firstly in order tomeet the requirements of the slow testing the control rateswere set constantly as 0033mms 0083mms 0166mms033mms 066mms and 083mms respectively Figure 7is the force-displacement curve of the STMR damper whenthe control rate is 0033mms from which it is clear that thewhole region is approximately divided into three parts elasticregion viscoelastic region and viscous region +e force-displacement curve displays a linear relationship in theelastic region a nonlinear relationship in the viscoelasticregion and gradually reaches stability in the viscous regionwhich tends to a certain value According to the force-displacement curve of the elastic region and Hookersquos lawthe elastic stiffness K of the STMR damper at differenttensile rates is calculated Figure 8 shows the relationshipbetween the elastic stiffness of the STMR damper and the
8 Advances in Materials Science and Engineering
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
γ = 5γ = 10 γ = 1
γ = 05
020
018
016
014
012
010
008
006
004
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
(a)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
036034032030028026024022020018016014012010008006004
(b)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
12
10
08
06
04
02
00
(c)
γ = 5γ = 10 γ = 1
γ = 05
Shea
r sto
rage
mod
ulus
Gprime (
MPa
)
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
18
16
14
12
10
08
04
06
02
00
(d)
γ = 5γ = 10 γ = 1
γ = 05
00 01 02 03 04 05 06 07 08 09Magnetic flux density B (T)
Shea
r sto
rage
mod
ulus
Gprime (
MPa
) 18
20
16
14
12
10
08
04
06
02
00
(e)
Figure 6 e shear storage modulus of MRSP samples as a function of magnetic ux density at dierent shear strains (a) MRSP 1 (b)MRSP 2 (c) MRSP 3 (d) MRSP 4 and (e) MRSP 5
Advances in Materials Science and Engineering 9
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
control rate from which it is detected that the greater thecontrol rate is the greater the elastic stiness of the STMRdamper becomes When the set control rate equals to0033mms elastic stiness tends to be less than 30 kNmmhowever when the control rate is up to 083mms theelastic stiness exceeds 65 kNmm which is twice as muchas that of the former Accordingly it proves that under thecondition of a slow testing the STMR damper exhibitsa certain rate sensitive characteristic
e fast testing displays that the STMR damper can beinstantaneously locked at a certain rate to transfer thedesigned load According to AASHTO when a fast testing iscarried out the locking distance should be within 12mm[19] Figure 9 shows the force-displacement curves with
a constant control rate of 6mms 8mms and 10mmsrespectively It is observed that when the force is loaded from0 to 300 kN the locking distances under the three controlrates are all less than 12mm which is in full compliance withthe provisions of AASHTO Nevertheless when the controlrate increases the lock distance and locking time tend toshorten e locking distance under the control rate of10mms is approximately 8mm and the locking time is only08 s which achieves instant locking while on the otherhand the lock times of the other two groups under thecontrol rates are both more than one second ereforecombined with these experimental results the developedSTMR damper accomplishes the locking function withina short time and distance which reveals that the STMRdamper can be simplied as a ldquorate switchrdquo with a lockingrate of 10mms meaning that instant locking happens whenthis rate is exceeded
44 Dynamic Mechanical Properties of the STMR DamperWhen the amplitude is within the range of the maximumcompression of the buttery spring only the main piston of
100
80
60
40
20
Forc
e (kN
)
Displacement (mm)20 22 24 26 28 30
Viscoelastic region Viscous region
Elastic region
Figure 7 Division of the displacement-resistance region
0 10 20 30 40 50
70
65
60
55
50
45
40
35
30
25
Stiff
ness
K (k
Nm
m)
Velocity v (mmmin)
066 mms
033 mms
083 mms
0166 mms
0083 mms
0033 mms
Figure 8 Relationship between velocity and spring stiness
Table 4 Gprimemax Gprimemin AMRe and RMRe of the MRSP samples
SamplesShearstrain
c
Gprimemax(MPa)
Gprimemin(MPa)
AMRe(MPa)
RMRe()
MRSP 1
05 0184 00666 01174 176281 0167 00619 01051 169795 0119 00547 00643 1175510 0100 00393 00607 15445
MRSP 2
05 0340 00796 02604 327141 0281 00692 02118 306075 0169 00590 01100 1864410 0135 00398 00952 23920
MRSP 3
05 1120 02770 08430 304331 0934 02390 06950 290795 0484 01150 03690 3208710 0340 00498 02902 58273
MRSP 4
05 1630 04020 12280 305471 1360 03530 10070 285275 0735 02010 05340 2656710 0480 00669 04131 61749
MRSP 5
05 1960 04340 15260 351611 1770 03660 14040 383615 0907 02140 06930 3238310 0592 00843 05077 60225
ndash2 0 2 4 6 8 10 12 14 16 18Displacement (mm)
300
250
200
150
100
50
0
Forc
e (kN
)Lock distance
10 mms
8 mms
6 mms
Figure 9 e relationship between displacement and resistanceforce
10 Advances in Materials Science and Engineering
the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
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the STMR damper works When the amplitude exceeds themaximum compression of the buttery spring the main andaccessory pistons work together resulting in a greater outputof damping force Since the interior of the STMR damper islled by MRSPs with the rate sensitive characteristic it isnecessary to conrm the dynamic rate sensitive perfor-mance So the excitation frequency of 01Hz 05Hz 10Hz15Hz and 25Hz were respectively applied under a dis-placement of 5mm e experimental results are displayedin Figure 10 From the experimental curve it is sensed thatunder the condition of small displacement within a fre-quency range of 01Hzndash25Hz the damping force changesfrom 603 to 2695 kNe higher the excitation frequency isthe greater the shear rate of materials in the interior of thedamper comes to be the larger the damping force becomesand the more apparent the rate sensitive characteristic turnsout to be Besides the ratio between the maximum andminimum damping force is 45 showing that when theexcitation frequency is more than 15Hz the damping forcegradually tends to saturation and the change range islimited which is consistent with the rate sensitive perfor-mance of the MRSP samples When the excitation frequencyenhances the envelope area of the damping force-displacementcurve inclines to enlarge indicating that the energy dissipationcapacity of the STMR damper becomes stronger and thefrequency directly aects the energy dissipation capacity of theSTMR damper e force of the buttery spring is super-imposed on the STMR damper which leads to the slant of thehysteresis curve
In order to validate the adjustable characteristic of themechanical properties for the STMR damper under the eectof the magnetic eld the dynamic mechanical propertieswere investigated under dierent currents during which thesame displacement control was adopted and each workingcondition was circulated for 10 times e testing conditionswere as follows the displacement was 5mm the frequencies
were 01Hz 05Hz 10Hz and 15Hz and a current of 0 A1A 2A and 3A was applied in each case respectivelyWhen the displacement was 55mm and the frequency was01Hz a current of 0 A 1A 2A and 3A was similarlyapplied nevertheless when the input current increased insequence the magnetic ux density in the working gap of theSTMR damper also enhanced and the damping force of thedamper also correspondingly magnied as well Figure 11presents the experimental results under the above testingconditions showing from the damping force-displacementcurves that whether it is under the condition of small dis-placement or large displacement and the STMR damperexhibits certain mechanical property of magnetic eldcontrollability
As shown in Figure 11 frequency is an important factorthat aects the adjustable range of the damping force of theSTMR damper under a small displacement of 5mm InFigure 11(a) the excitation frequency is 01Hz presentingthat when the input current changes from 0 to 3A thevariation range of the damping force is 603ndash1893 kN andthe ratio between the maximum and minimum dampingforce is approximately 31 In Figures 11(b)ndash11(d) theexcitation frequencies are 05Hz 10Hz and 15Hzrespectively revealing the fact that when the current changesfrom 0 to 3A the ratio between the maximum and mini-mum damping force becomes 20 14 and 12 respectivelyAccordingly the increase of frequency directly aects theadjustable range of the damper under the excitation of themagnetic eld which demonstrates that the higher the fre-quency is the narrower the adjustable range turns out to beis is for the reason that the high excitation frequency makesthe lling materials to stien and the soft magnetic particlesin the magnetic eld are chain blocked which is not ad-vantageous to stimulate the magnetorheological eect andthereby makes the adjustable range of the damper undermagnetic eld narrow down In Figure 11(e) under thecondition of a displacement of 55mmwith low frequency andlarge displacement the damper presents the obvious char-acteristic of magnetic eld controllability When the inputcurrent changes from 0 to 3A the variation range of thedamping force is 2128ndash2721 kN and the ratio between themaximum andminimumdamping force is approximately 13When the damper is under the condition of large displace-ment since the buttery spring works together with the mainand accessory cylinder tubes after the compression limit thehysteresis curve displays a certain sag in the positive andnegative strokes
In the structural vibration control as the external ex-citation frequency is not enough to make the STMR damperinduce the speed locking it is given full play to the ad-justment ability of the damper in the magnetic eld whichindicates that the STMR damper can be simplied to a largertraditional MR damper
45 Dynamic Hysteretic Mechanical Model for the STMRDamper e dynamic damping force of the STMR dampercan be decomposed into a superposition of three compo-nents of force the rst component of force refers to applied
Displacement (mm)
300250200150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6
01 Hz05 Hz10 Hz
15 Hz25 Hz
Figure 10 Relationship between the damping force and dis-placement for the STMR damper
Advances in Materials Science and Engineering 11
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
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Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
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ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
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ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(a)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(b)
200250300
150100
500
ndash50ndash100ndash150ndash200ndash250ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(c)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A10 A
20 A30 A
(d)
300
200
100
0
ndash100
ndash200
ndash300
Dam
ping
forc
e (kN
)
ndash60 ndash40 ndash20 0 20 40 60Displacement (mm)
0 A10 A
20 A30 A
(e)
Figure 11 Relationship between damping force and displacement for the STMR damper at dierent frequencies and displacements (a)01Hz 5mm (b) 05Hz 5mm (c) 10Hz 5mm (d) 15Hz 5mm (e) 01Hz 55mm
12 Advances in Materials Science and Engineering
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
force fmr which is produced by the magnetorheologicaleffect of the material which is related to the current orexerted magnetic field strength the second component offorce fpm stands for the applied force to describe thecharacterization of polymer properties which is connectedwith external excitation rate or strain rate as for fbs itmeans the additional force of the butterfly spring whichsatisfies with Hookersquos Law
+e first component of force fmr can be expressed as
fmr kprime1u + cprime _u + fp (4)
where kprime1 and cprime are the stiffness and damping coefficientsdepending on the magnetic field strength respectively u and_u stand for the displacement and speed rate fp is thehysteretic subitem which is controlled by the followingBoucndashWen differential equation
fprimep α _uminus β _u fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus c| _u|fp fp
11138681113868111386811138681113868
11138681113868111386811138681113868nminus1
αminus β + c sgn _ufp1113872 11138731113960 1113961 fp
11138681113868111386811138681113868
11138681113868111386811138681113868n
1113882 1113883 _u(5)
where α β c and n are all the parameters to control theshape of the hysteretic curve
+e second component of force fpm refers to the ma-terial viscoelasticity or nonlinear stiffness characteristicwhich can be expressed as
fpm kPrime1u + kPrime3u + cPrime _u (6)
where kPrime1 kPrime3 and cPrime are the stiffness and damping co-efficients depending on the speed rate or the strain raterespectively
+e third component of force fbs means the additionalforce of the butterfly spring when under the situation thatthe excitation amplitude is less than the maximum com-pression of the butterfly spring according to Hookersquos law itis expressed as
fbs kbsu (7)
where kbs stands for the stiffness of the butterfly springBased on (4) (6) and (7) the damping force of the
STMR damper can be expressed as
f fmr + fpm + fbs k1 + kbs( 1113857u + k3u3
+ c _u + λfp
(8)
where k1 kprime1 + kPrime1 k3 kPrime3 c cprime + cPrime and λ representsthe proportional coefficient between the hysteretic andnonhysteretic force All the stiffness and damping coefficientsdepend on the strain rate and magnetic field density
For the dynamic mechanical properties of the STMRdamper it can be considered that the shear storage modulusof the MRSPs contributes to the stiffness part of the devicestructure whereas the damping characteristic of the materialcontributes to the damping part of the device structureConsequently in (8) the stiffness coefficients k1 and k3damping coefficient c and ratio coefficient λ can be rewritteninto functions of magnetic field and speed rate as belowrespectively Furthermore related studies revealed that
stiffness and damping are almost linearly dependent on theexternal magnetic field and strain rate [20]
k1 k10 He( 1113857 + k11 He( 1113857| _u| + k12 He( 1113857| _u|2 (9)
k3 k30 He( 1113857 + k31 He( 1113857| _u| (10)
c c0 He( 1113857 + c1 He( 1113857| _u| (11)
λ λ0 He( 1113857 + λ1 He( 1113857| _u| (12)
where k10 k11 k12 k30 k31 c0 c1 λ0 and λ1 are ap-proximated as the linear equation of the external magneticfield He
+e displacement hysteresis phenomenon of the STMRdamper is caused by the subitem fp of the hysteretic forcetherefore in combination with (5) the hysteretic force canbe expressed as
F1 fp1113872 1113873 uminus u+
F2 fp1113872 1113873 uminus u+
F3 fp1113872 1113873 uminus uminus
F3 fp1113872 1113873 uminus uminus
or fp Fminus11 uminus u+( 1113857 _uge 0 fp ge 0
fp Fminus12 uminus u+( 1113857 _uge 0 fp le 0
fp Fminus13 uminus uminus( 1113857 _ule 0 fp ge 0
fp Fminus14 uminus uminus( 1113857 _ule 0 fp le 0
(13)
where Fi(fp) (i 1 2 3 4) represents the function of fpand Fminus1i (fp) means the inverse function of Fi(fp) Fur-thermore u+ and uminus respectively refer to the lagging dis-placement produced in the positive and negative directionsof the equilibrium position In the testing process the up-ward of the balanced position is positive while the down-ward of the balanced position is negative In a cycle once thepeak and valley values of the displacement are equal and thelagging displacement of the positive and negative directionsreaches equivalence the hysteresis curve presents thesymmetric characteristic Besides when n 1 and β c (5)can be simplified to
fp
αβ + c
1minus eminus(β+c) uminusu+( )1113876 1113877 _uge 0 fp ge 0
α uminus u+( 1113857 _uge 0 fp le 0
α uminus uminus( 1113857 _ule 0 fp ge 0
minusαβ + c
1minus e(β+c) uminusuminus( )1113876 1113877 _ule 0 fp le 0
⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
(14)
+erefore according to (8) and (14) the damping forceof the STMR damper can be ultimately expressed as
Advances in Materials Science and Engineering 13
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
f
k1 + kbs( )u + k3u3 + c _u + λ
αβ + c
1minus eminus(β+c) uminusu+( )[ ] _uge 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λα uminus u+( ) _uge 0 fp le 0
k1 + kbs( )u + k3u3 + c _u + λα uminus uminus( ) _ule 0 fp ge 0
k1 + kbs( )u + k3u3 + c _u + λ
minusαβ + c
1minus e(β+c) uminusuminus( )[ ] _ule 0 fp le 0
(15)
As a result the stiness coecurrencients k1 and k3 thedamping coecurrencient c and the ratio coecurrencient λ are ex-panded from (9)ndash(12) respectively
Marquardt algorithm was adopted to carry out the pa-rameter identication on the damping mechanical model ofthe STMR damper Low frequency and small displacementexperimental data were selected among which the excitationfrequency was 01Hz the amplitude was 5mm and thecurrent input was 0A 1A 2A and 3A respectively Fromthe experimental data it can be perceived that the laggingdisplacement in both positive and negative directions is2mm whereas 14 parameters based on the symmetric dy-namic hysteretic mechanical model were identied eidentication results are listed in Table 5 Figure 12 displaysthe comparison between the dynamic hysteresis experi-mental curves of the STMR damper and the model hysteresiscurve acquired by parameter identication presenting thatthe model curve stands in good agreement with the ex-perimental data which further validates the correctness ofthe multiparameter and symmetric dynamic hystereticmodel and indicates that the method of parameter iden-tication is eective
5 Conclusions
In this work a novel STMR damper with rate sensitivecharacteristic (speed locking) and semiactive controllingproperty was designed and fabricated based on multi-functional composite MRSPs Both the mechanicalproperties of MRSPs and the STMR damper were ex-perimentally investigated Firstly the MRSP 5 and MRSP0 samples exhibited the best magnetorheological eectand relative shear stiening eect respectively whichwere chosen as the llers of the main cylinder and ac-cessory cylinder Secondly through slow and fast ex-periments the STMR damper presented an obvious ratesensitive property and realized the speed locking func-tion in a short time and distance when external excitationrate was fast enough Besides dynamic experiment re-sults indicated that the damping force of the STMRdamper could be controlled by the excitation frequencyand the applied magnetic eld Finally a multiparameterand symmetry hysteretic model was proposed to describethe dynamic hysteretic behavior of the STMR damperwhich agreed well with the experimental data
Table 5 Results of the parameter identication
Parameters I 0A I 1A I 2A I 3Ak10 minus015 minus000049 535 minus4887k11 3359 585 minus1303 2970k12 minus5771 minus8202 1416 minus103k30 045 0022 025 minus014k31 minus043 0027 minus034 009c0 minus4523 23850 6114 30736c1 14315 031 6555 minus9370λ0 000083 094 201 minus145λ1 2320 6074 255 2609α 123 135 038 102β 0033 0022 050 001λ 0033 0022 050 001n 1 1 1 1kbs 040 040 040 040
200
150
100
50
0
ndash50
ndash100
ndash150
ndash200
Dam
ping
forc
e (kN
)
ndash6 ndash4 ndash2 0 2 4 6Displacement (mm)
0 A experimental data1 A experimental data2 A experimental data
3 A experimental dataModel curve
Figure 12 e relationship between the model curve and ex-perimental data of the STMR damper
14 Advances in Materials Science and Engineering
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
Conflicts of Interest
+e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
+is work was supported by Primary Research and Devel-opment Plan of Jiangsu Province (Grant no BE2017167)Natural Science Foundation of Zhejiang Province (Grant noLY15E080015) National Natural Science Foundation ofChina (Grant no 51508237) Natural Science Foundation ofJiangsu Province (Grant no BK20140560) and ResearchFoundation for Advanced Talents of Jiangsu University(Grant no 14JDG161)
References
[1] F Guo C B Du G J Yu and R P Li ldquo+e static anddynamic mechanical properties of magnetorheological sillyputtyrdquo Advances in Materials Science and Engineering vol2016 Article ID 7079698 11 pages 2016
[2] X Z Zhang W H Li and X L Gong ldquoStudy on magne-torheological shear stiffening fluidrdquo Smart Materials andStructures vol 17 no 1 p 015051 2008
[3] G R Peng W H Li T F Tian J Ding and M NakanoldquoExperimental andmodeling study of viscoelastic behaviors ofmagneto-rheological shear stiffening fluidsrdquo Korea-AustraliaRheology Journal vol 26 no 2 pp 149ndash158 2014
[4] S Wang W Jiang W Jiang et al ldquoMultifunctional polymercomposite with excellent shear stiffening performance andmagnetorheological effectrdquo Journal of Materials Chemistry Cvol 2 no 34 pp 7133ndash7140 2014
[5] Y Wang S Wang C Xu S Xuan W Jiang and X GongldquoDynamic behavior of magnetically responsive shear-stiffeninggel under high strain raterdquo Composites Science and Technologyvol 127 pp 169ndash176 2016
[6] B Sapinski ldquoParametric identification of MR linear auto-motive size damperrdquo Journal of eoretical and AppliedMechanics vol 40 no 3 pp 703ndash722 2002
[7] W L Qu S Q Qin J W Tu et al ldquoIntelligent control forbraking-induced longitudinal vibration responses of floating-type railway bridgesrdquo Smart Materials and Structures vol 18no 12 p 125003 2009
[8] W L Qu J Liu J W Tu M Run and H Cheng ldquoCrucialtechniques for design of 500 kN large-scale MR damperrdquoEarthquake Engineering and Engineering Vibration vol 27no 2 pp 124ndash130 2007 in Chinese
[9] W L Qu M Run and J W Tu ldquoDesign and simulation ofa new full scale MR damperrdquo Journal of Wuhan University ofTechnology vol 29 no 2 pp 87ndash90 2007 in Chinese
[10] W L Qu S Q Qin J W Tu J Liu and Q Zhou ldquo+eory andcrucial technologies of intelligent control for response in deckand towers of Wuhan Tianxingzhou cable-stayed bridgesubjected to train brakingrdquo China Civil Engineering Journalvol 43 no 8 pp 63ndash72 2010 in Chinese
[11] G J Yu C B Du and T Sun ldquo+ermodynamic behaviors ofa kind of self-decoupling magnetorheological damperrdquo Shockand Vibration vol 2015 Article ID 502747 9 pages 2015
[12] G J Yu C B Du and F X Wan ldquoDesign and experimentalstudies on self-decoupling magneto-rheological damperrdquoJournal of Vibration Measurement and Diagnosis vol 32no 3 pp 426ndash431 2012 in Chinese
[13] G J Yu and C B Du ldquoDesign and experimental studies oncomposite magneto-rheological damperrdquo Chinese Quarterlyof Mechanics vol 35 no 1 pp 131ndash138 2014 in Chinese
[14] G J Yu T Sun B Su et al ldquoResearch of architecturalstructures semi-active control based on SDMR damperrdquoJournal of Chongqing University of Technology (Nature Sci-ence) vol 29 no 11 pp 42ndash50 2015 in Chinese
[15] X Z Zhang W H Li and X L Gong ldquo+e rheology of shearstiffening fluid (STF) and the dynamic performance of anSTF-filled damperrdquo Smart Materials and Structures vol 17no 3 p 035027 2008
[16] H Zhou C Y Guo L H Zong et al ldquoPerformance of shearstiffening fluid and a damper as its applicationrdquo Journal ofVibration and Shock vol 32 no 18 pp 15ndash20 2013 inChinese
[17] J Liang and X H Zhang ldquoRheological properties of SP inshock transmission applicationrdquo Journal of Materials in CivilEngineering vol 27 no 9 p 04014250 2015
[18] L C Davis ldquoModel of magnetorheological elastomersrdquoJournal of Applied Physics vol 85 no 6 pp 3348ndash3351 1999
[19] AASHTO AASHTO LRFD Bridge Construction SpecificationsAmerican Association of State Highway and TransportationOfficials Washington DC USA 2012
[20] C Collette G Kroll G Saive V Guillemier and M AvraamldquoOn magnetorheologic elastomers for vibration isolationdamping and stress reduction in mass-varying structuresrdquoJournal of Intelligent Material Systems and Structures vol 21no 15 pp 1463ndash1469 2010
Advances in Materials Science and Engineering 15
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom
CorrosionInternational Journal of
Hindawiwwwhindawicom Volume 2018
Advances in
Materials Science and EngineeringHindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Journal of
Chemistry
Analytical ChemistryInternational Journal of
Hindawiwwwhindawicom Volume 2018
ScienticaHindawiwwwhindawicom Volume 2018
Polymer ScienceInternational Journal of
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
Advances in Condensed Matter Physics
Hindawiwwwhindawicom Volume 2018
International Journal of
BiomaterialsHindawiwwwhindawicom
Journal ofEngineeringVolume 2018
Applied ChemistryJournal of
Hindawiwwwhindawicom Volume 2018
NanotechnologyHindawiwwwhindawicom Volume 2018
Journal of
Hindawiwwwhindawicom Volume 2018
High Energy PhysicsAdvances in
Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom
The Scientific World Journal
Volume 2018
TribologyAdvances in
Hindawiwwwhindawicom Volume 2018
Hindawiwwwhindawicom Volume 2018
ChemistryAdvances in
Hindawiwwwhindawicom Volume 2018
Advances inPhysical Chemistry
Hindawiwwwhindawicom Volume 2018
BioMed Research InternationalMaterials
Journal of
Hindawiwwwhindawicom Volume 2018
Na
nom
ate
ria
ls
Hindawiwwwhindawicom Volume 2018
Journal ofNanomaterials
Submit your manuscripts atwwwhindawicom