Research Article Design and Fabrication of Air-Based 1-3 ...downloads.hindawi.com/journals/js/2016/4982616.pdf · Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer

Research ArticleDesign and Fabrication of Air-Based 1-3 Piezoelectric CompositeTransducer for Air-Coupled Ultrasonic Applications

Cunfu He Yaoyao Wang Yan Lu Yuepeng Liu and Bin Wu

College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Beijing 100124 China

Correspondence should be addressed to Yan Lu lvyanbjuteducn

Received 20 February 2016 Revised 12 May 2016 Accepted 26 May 2016

Academic Editor Manel del Valle

Copyright copy 2016 Cunfu He et alThis is an open access article distributed under theCreativeCommonsAttributionLicense whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The air-based 1-3 piezoelectric composite transducers are designed and fabricated in order to solve the acoustic impedancematchingproblem Firstly a finite element model using honeycomb structure as the piezoelectric composite matrix is built to reduce theacoustic impedance of the sensitive element Three important factors volume fraction of piezoelectric materials 120593 the thickness ℎand the size 119904 of the square cross section of piezoelectric column are examined and verified in simulation Then according to theresult of simulation the piezoelectric composites and the air-coupled transducers are fabricatedThe honeycomb structures of resinare produced by the method of 3D printing technology with the volume fraction of air being 30 The impedance characteristicsand the excitationreception performance of the air-coupled transducers are measured and optimized Meanwhile a scanningexperiment is carried out to demonstrate the crack detection process in monocrystalline silicon119860

0mode of Lamb waves is excited

and collectedThe location and size of the defect will be determined by calculating the correlation coefficients of the received signalsand reference signals Finally a 15mm times 05mm times 05mm scratch is clearly distinguished

1 Introduction

Silicon is one of themost important components of solar cellsand the original integrality of silicon wafer affects the pho-toelectric conversion efficiency and service life significantlySo a suitable nondestructive testing and evaluation methodshould be performed to inspect the cracks in silicon wafer

In many researches the damage detection for siliconwafer is mainly classified into several methods whichinclude resonance ultrasonic vibrations [1] and ultrasonicguided waves [2] With the increasing demand for high-speed inspection nondestructive inspection modes usingultrasonic guided waves have become a research hotspotThe nondestructive inspectionmodes can be broadly dividedinto contact methods and noncontact methods At presentthe methods of noncontact ultrasonic testing are mainly air-coupled ultrasonic testing [3] laser ultrasonic testing [4] andelectromagnetic ultrasonic testing [5]

Air-coupled ultrasonic testing avoids the specimen con-tact in order to wipe the influence of contact conditions andcoupling materials Then only air will be used as the cou-pling medium and the transducer can easily move to make

it possible to do scanning quickly Air-coupled ultrasonictesting includes penetration detection pulse-echo testingand oblique incident detection Kichou et al [6] used air-coupled transducers to excite pure Lamb waves in plate Therelationship between the deviation of Lamb wave beam andthe inclination angle of specimen is researched Solodov etal [7] demonstrated the periodic distribution of Lamb waveamplitudes and phases along the various directions in siliconwafer by air-coupled transducers Yan et al [8] investigatedthe impact of delamination in a carbon-epoxy compositeplate The group velocity of air coupling Lamb waves isextracted to identify the positions of defects Chakrapani et al[9] experimentally located the crack in both monocrystallineand polycrystalline siliconwafer with the thickness of 200120583musing linear scanning method by 119860

0mode Lamb waves Liu

et al [10] utilized the air-coupled ultrasonic transducers togenerate and receive Lamb waves in composite beams fordelamination detection and analyzed the reflection andmodeconversion at the ends of lamination defects

However the main restriction associated with air cou-pling method is the large acoustic impedance mismatch at

Hindawi Publishing CorporationJournal of SensorsVolume 2016 Article ID 4982616 11 pageshttpdxdoiorg10115520164982616

2 Journal of Sensors

the transducerair and airspecimen interfaces wheremost ofthe incident wave will be reflected [5] When the ultrasoundpasses through an interface only a proportion of it can becoupled into the next materialThis ldquoproportionrdquo depends onhow close the acoustic impedance of these two materials isThe acoustic impedance of traditional piezoelectric ceramicmaterials is almost (30sim40) times 106 Rayl but that of air is only420 Rayl So the proportion of the ultrasound that is coupledinto the air will be only 0003sim0005

The active materials 1-3 type piezoelectric compositescomposed of polymer (epoxy resin or polyurethane) andpiezoelectric ceramic can reduce the acoustic impedancesignificantly Hence the transmitted proportion (from trans-ducer to air) can be increased Generally the 1-3 typepiezoelectric composites possess the following attributes lowdensity low acoustic impedance wide bandwidth and highelectromechanical coupling coefficient Newnham et al [11]first put forward the concept of 1-3 piezoelectric compositesBased on their study extensive researches have been car-ried out Hayward and Bennett [12] analyzed the workingcharacteristic of 1-3 piezoelectric composite transducers byfinite element method Hladky-Hennion and Decarpigny[13] observed the influence of geometrical parameters on1-3 piezoelectric composites by establishing a cycle modelBhardwaj [14] firstly proposed the prototype of air-basedpiezoelectric composites sensors using honeycomb structureor foam material as the substrate to reduce the density andacoustic impedance

To sum up in this paper air-based 1-3 piezoelectriccomposites air-coupled transducer will be introduced andevaluated Firstly the structure of piezoelectric composites ismanipulated Secondly 3D finite element models are createdto analyze the performance of air-based 1-3 piezoelectriccomposites Then the transducers based on 1-3 piezoelectriccomposites are fabricated with the honeycomb structuresof resin which are produced by 3D printing Also theexcitation and reception performance are tested Finallythese transducers will be applied in the crack detection bygenerating and receiving Lamb waves

2 3D Simulations of1-3 Piezoelectric Composites

21 1-3 Piezoelectric Composites and Their Finite ElementModel (FEM) As shown in Figure 1 conventional 1-3 piezo-electric composites are composed of piezoelectric columnswhich are mounted inside the polymer parallelly and period-ically The structure can reduce the density and decrease theacoustic impedance effectively This will close the impedancebetween piezoelectric transducer and the air so as to let moreultrasound through

In order to reduce the acoustic impedance of the piezo-electric composites significantly air-based 1-3 piezoelectriccomposites should be induced The structure and compo-nents of air-based 1-3 piezoelectric composites are shown inFigure 2 Using honeycomb structure as a matrix of piezo-electric composites the piezoelectric columns are embeddedin the cellular structure The honeycomb structure acts as a

Piezoelectric column

Polymer

Figure 1 Conventional 1-3 piezoelectric composites


Polymer

Air

Figure 2 Air-based 1-3 piezoelectric composites

skeleton to support the piezoelectric column However theair gap (instead of the filling polymer in Figure 1) reduces thedensity and the acoustic impedance efficiently Thus the airbecomes the main part of the composite matrix And this iswhere the ldquoair baserdquo comes from

According to 1-3 piezoelectric composites thickness-mode oscillation theory [15] the acoustic impedance of 1-3piezoelectric composites can be formulated by

119885 = (11988833120588)12

(1)

where 119885 11988833 and 120588 are the generalized acoustic impedance

elastic constants and density respectively 11988833

and 120588 of 1-3 piezoelectric composites are determined by the volumefraction and the original elastic constants and density of eachown phase Comparedwith the conventional 1-3 piezoelectriccomposites the air-based 1-3 piezoelectric composites usehoneycomb structure as a matrix which will inevitablyreduce the acoustic impedance For example when 120593 =

40 epoxy 30 and air 30 we can obtain the generalizedacoustic impedance which equals 128 times 107 kgsdotmminus2sdots whilethe conventional one equals 137 times 107 kgsdotmminus2sdots It shows a7 decreaseTherefore at the same PZT volume fraction theacoustic impedance of air-based 1-3 piezoelectric compositesis lower than that of epoxy-based 1-3 piezoelectric compos-ites

Journal of Sensors 3

Table 1 Material parameters of PZT-5H

120588

kgm3119888 1010Nm2 119890 Cm2 120576120576

0

11988811

11988812

11988813

11988833

11988844

11988866

11989033

11989031

11989015

12057611

12057633

7500 126 795 841 117 23 235 233 minus65 17 1700 1470

ffs fpO

|Z|

Figure 3 Typical characteristic impedance curve of piezoelectricmaterials

When an electrical signal is applied to the piezoelectricmaterials the equivalent impedance of the piezoelectricelement will change along with the exciting frequency Thecharacteristic impedance curve of piezoelectric materials isshown in Figure 3 The minimum of this curve correspondsto the series resonant frequency 119891

119904 while the maximum of

impedance represents the parallel resonant frequency 119891119901

In this research the electromechanical coupling coeffi-cient 119870

119905and the mechanical quality factor 119876

119898are selected

as the critical factor to evaluate the performance of thepiezoelectric composites 119870

119905is a quantity that measures the

conversion efficiency between electrical energy and acousticenergy in piezoelectric materials For thickness vibrationmode of 1-3 piezoelectric composites the electromechanicalcoupling coefficient 119870

119905can be formulated by

1198702

119905=

120587

2

119891119904

119891119901

tan(120587

2

119891119901minus 119891119904

119891119901

) (2)

119876119898

is a quantity that measures the wastage of energyovercoming the internal friction when the piezoelectricmaterials resonate Usually this part of energy turns out to beheat The mechanical quality factor 119876


119876119898=

1198912

119901

2120587119891119904 |119885| 119862

119879 (1198912119901minus 1198912119904) (3)

where |119885| is the minimum of the resonant impedance 119862119879 isthe free capacitance Accordingly when 119876

119898is greater more

energy turns into mechanical oscillationAir-based 1-3 piezoelectric composites are formed by the

same structural unit in a certain periodical arrangementIn this repeatable unit there exist two symmetrical planesas shown in Figure 4 One-quarter of the unit is called acell If symmetrical boundary conditions are set to the finiteelement model actually the performance of the air-based 1-3 piezoelectric composites can be obtained by only one cell

Table 2 Material parameters of epoxy resin

120588 kgm3 119888119879 ms 119888

119871 ms 120576120576

0

CY1301HY1300 1140 1140 2370 4

model In order to study the performance of 1-3 piezoelectriccomposites PZT-5H is selected as the piezoelectrics whileepoxy resin is the polymer matrix The material parametersare shown inTables 1 and 2The 3DFE simulations are carriedout using COMSOL Multiphysics (COMSOL Inc Sweden)with symmetrical boundary conditions The finite elementmodel of one cell of air-based 1-3 piezoelectric compositesis illustrated in Figure 4 In FE model the volume fraction120593 of PZT is gradually increased from 10 to 60 with theinterval of 10 the cross-sectional area 119904 of the piezoelectricsquare column is increased from 1mm times 1mm to 3mmtimes 3mm with the side length stepping by 05mm and thethickness ℎ of piezoelectric column is increased from 5mmto 10mm with the interval of 1mm The element chosea 3-dimensional brick type The element sizes in length(119909 direction) in width (119910 direction) and in thickness (119911direction) are all 02mm approximately 110 wavelengthThescanning frequency ranges from 50 kHz to 500 kHz with theinterval of 1 kHz

22 Influence of PZT Volume Fraction 120593 In the compositematerial the content of piezoelectrics directly affects thepiezoelectric propertiesWith the increase of volume fractionof PZT the piezoelectric constant and dielectric constant ofcomposite material will increase Meanwhile the acousticimpedance of the composite material will also increase Soa suitable volume fraction of PZT should be optimized tobalance the piezoelectric constantdielectric constant and theacoustic impedance

In the finite element model of piezoelectric compositethe thickness ℎ and the cross-sectional area 119904 (red area) ofthe piezoelectric column are 10mm and 1mm times 1mm Thevolume fraction of PZT 120593 is gradually increased from 10to 60 with the interval of 10 while keeping the volumefraction of air 30 as shown in Figure 5

The simulation results are shown in Figures 6 and 7With the increase of volume fraction 120593 of the PZT theelectromechanical coupling coefficient119870

119905of 1-3 piezoelectric

composites will gradually increase while the mechanicalquality factor 119876

119898will gradually decrease When volume

fraction 120593 of the PZT is 40sim60 the electromechanicalcoupling coefficient 119870

119905tends to be stable and maximum

which means this electromechanical conversion efficiency isoptimized But the mechanical quality factor 119876

119898changes

slightly and is much lower than PZT-5H Meanwhile atthe same volume fraction the electromechanical coupling


Symmetrical boundary

A cell(14 of the cross section)

Air


Polymer

Figure 4 A quarter cycle finite element model of 1-3 piezoelectric composite

1020

30 40 50 60

12m

m

12 mm

Figure 5 Increase of PZT volume fraction 120593

Air-basedEpoxy-based

Kt

20 30 40 50 6010120593 ()

05

055

06

065

07

075

08

Figure 6 Influence of the PZT volume fraction on the electrome-chanical coupling coefficient

coefficient 119870119905of air-based 1-3 piezoelectric composites is

greater than that of epoxy-based 1-3 piezoelectric compositesfor almost 10 The volume fraction of 40 for PZT isselected to ensure both high electromechanical conversionefficiency and low acoustic impedance

23 Influence of PZT Cross-Sectional Area 119904 In the finiteelement model the thickness ℎ and the volume fraction 120593

of PZT are 10mm and 40 The cross-sectional area 119904 of thepiezoelectric square column is gradually increased from 1mmtimes 1mm to 3mm times 3mm with the side length stepping by05mm as shown in Figure 8


10

15

20

25

30

Qm

20 30 40 50 6010120593 ()

Figure 7 Influence of the PZT volume fraction on the mechanicalquality factor

The relationship between the electromechanical couplingcoefficient 119870

119905and the cross-sectional area 119904 is shown in

Figure 9 The change of 119904 of PZT has little impact on 119870119905

And the electromechanical conversion efficiency of air-based1-3 piezoelectric composites is greater than that of epoxy-based ones The influence of the cross-sectional area 119904 onthe mechanical quality factor 119876

119898is shown in Figure 10 The

change of 119904 of PZT also shows little impact on 119876119898

In the composite material the PZT cross-sectional area119904 mainly affects the vibration mode In general for piezo-electrics the vibration mode includes thickness vibrationmode and lateral vibration mode [16] Generally the greater


12 mm 152mm 22mm 252mm 32mm

Figure 8 Increase of PZT cross-sectional area 119904


Kt

05

055

06

065

07

075

08

2 4 6 8 100s (mm2)

Figure 9 Influence of the PZT cross-sectional area on the elec-tromechanical coupling coefficient

the thickness electromechanical coupling coefficient thestronger the thickness vibration mode the greater the planarelectromechanical coupling coefficient the stronger the lat-eral vibration mode For 1-3 piezoelectric composites whenthe PZT cross-sectional area is larger which means the largeraspect ratio (side lengththickness) the lateral vibrationmode will affect the thickness vibration mode significantlyleading to the fact that the thickness vibration mode will belimited So it is important to fabricate ldquolong and thinrdquo PZTcolumn Considering both the processing procedures and thecost the cross-sectional area of 1mm times 1mm is selected forthe PZT column

24 Influence of PZT Thickness ℎ The frequency constant ofPZT-5H is 119873 = 2000Hzsdotm The relationship between theresonant frequency 119891

0of thickness vibration mode and the

thickness of PZT ℎ can be formulated by

119873 = 1198910sdot ℎ (4)


Qm

10

12

14

16

18

20

2 4 6 8 100s (mm2)

Figure 10 Influence of the PZT cross-sectional area on themechan-ical quality factor

In the finite element model the cross-sectional area 119904 andthe volume fraction 120593 of PZT are 1mm times 1mm and 40Thethickness of piezoelectric column is gradually increased from5mm to 10mm with the interval of 1mm

As is shown in Figures 11 and 12 the electromechanicalconversion efficiency 119870

119905and the mechanical quality factor

119876119898both vary slightly with the increase of the thickness of

PZT ℎ However when the volume fraction of PZT 120593 isconstant with the increase of the PZT thickness ℎ the centerfrequency of air-coupled 1-3 piezoelectric composites isalmost linearly decreasing as is shown in Figure 13Thereforeaccording to the desired center frequency the appropriatethickness of the piezoelectric composites should be designed

According to the results of the above simulation analysisthe volume fraction of PZT is 120593 = 40 to ensure the optimalelectromechanical conversion efficiency and to keep the lowacoustic impedance The side length of PZT column is 119886 =

1mm to limit the lateral vibrationmodeThe thickness of thesensitive element is ℎ = 10mmto ensure the center frequencyof the air-coupled transducers to be about 200 kHz



Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08

Figure 11 Influence of the ceramic thickness on the electromechan-ical coupling coefficient


Qm

6 7 8 9 105h (mm)

10

15

20

25

30

Figure 12 Influence of the ceramic thickness on the mechanicalquality factor

3 Fabrication and Performance Test ofAir-Coupled Transducer

31 Air-Coupled Transducer Preparation and Impedance Char-acteristics Analysis Since the substrate of the air-based 1-3 piezoelectric composite is intensive honeycomb structurethe traditional mechanical method is not feasible for thefabrication In this research the honeycomb structures madeof resin are constructed by the method of 3D printingtechnology with the 30 volume fraction of air

The ProJet 3510 SD (3D Systems USA) 3D printer is usedto fabricate the honeycomb structure with the resin materialof VisiJet Crystal The honeycomb structure is divided intoseveral layers and printed layer by layerThe resolution of the


f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)

Figure 13 Influence of the ceramic thickness on the center fre-quency

Table 3 Frequency of series resonant and parallel resonant oftransducers

Number 119891119904

119891119901

1 1472 kHz 1661 kHz2 1553 kHz 1812 kHz3 1461 kHz 1679 kHz

3Dprinter is 32120583mtomake sure the precision of the structureis at 0025mmndash005mm Then a precise honeycomb struc-ture will be obtainedThe piezoelectric columns aremanuallyinserted into the honeycomb structures both combined byepoxy adhesive After curing the upper and bottom surfacesare polished Then the gold is sputtered on the two surfacesas electrodes Finally when the air-based 1-3 piezoelectriccomposites are packaged up with the shield the air-coupledtransducer will be complete as shown in Figure 14 Theimpedance characteristics of the air-coupled transducers aremeasured by an impedance analyzer (Agilent 4294A) Theresults are shown in Figure 15 The characteristic impedancecurves of the transducers differ a little The frequencies ofseries resonant 119891

119904and parallel resonant 119891

119901 shown in Table 3

are slightly different Meanwhile because the aspect ratioof the piezoelectric column is relatively small the lateralvibration mode is far away from the thickness vibrationmode So the pure thickness vibration mode is approached

32 Air-Coupled Transducer Performance Test The air-coupled transducers are tested The transducer arrangementis shown in Figure 16 The distance between the transmittingtransducer and the receiving transducer is 80mmThe directwave signals transmitted through the air are detected

The excitation signal is a 5-cycle 200 kHz sinusoidal toneburst modulated by a Hanning windowThe received signalsare shown in Figure 17 As can be seen from the resultsthe air-coupled transducers can both excite and receive the


(a)

Number 1 Number 2 Number 3

(b)

Figure 14 Schematic representation of 1-3 piezoelectric composite and air-coupled transducers (a) air-based 1-3 piezoelectric composite and(b) air-coupled transducers

02 03 0401Frequency f (MHz)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)

Figure 15 Impedance curves of air-coupled transducers (a) number 1 (b) number 2 and (c) number 3


T R

80mm

Figure 16 Transducer arrangement of testing experiment

100 150 200 250 300 350

024

A (m

V)

From number 1 to number 2






Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

Figure 17 Performance test results of air-coupled transducers at200 kHz

ultrasound in the air and the signal-to-noise ratio (SNR)of direct wave signals seems to be very well According tothe received waveform signals in the subsequent experimentof defect detection number 3 transducer is selected astransmitter to emit an ultrasonic pulse while number 2transducer is selected as receiver

According to the fabrication and performance test of air-coupled transducer it is feasible to introduce 3D printingmethod to fabricate a transducer However because all of theair-coupled transducers are handmade the consistency is notvery good Hence the excitation and reception performanceof air-coupled transducers differMeanwhile as the transduc-ers do not include matching and backing layer the receivedwaveforms trail a lot

4 Experiment of Defect Detection

Lambwaves are ultrasonic guidedwaves formed by the super-position of longitudinal and transverse waves propagating ina plate-like structure in which the thickness is comparable

0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0

Frequency thickness fd (MHzmiddotmm)

Figure 18 Incident angle dispersion curves of Lamb waves along⟨110⟩ orientation for monocrystalline silicon wafer

to the wavelength Lamb waves can travel relatively long dis-tances with little attenuation in plate structures [17] and theyare sensitive to both surface and subsurface discontinuities[18]

The Lamb wave generated by air-coupled transducers isintroduced into the production and quality control process ofmonocrystalline silicon and the final purpose is to determineand detect the defects nondestructively [19] Due to thecenter frequency of excitation and the thickness of the platesdifferent symmetric mode (119878

0) and antisymmetric mode

(1198600) should be induced In this case 200 kHz is chosen as

the excitation frequency The signal received by air-coupledtransducer is the leaky wave from the silicon surface 119878

0

mode possesses mainly in-plane displacement whereas out-of-plane displacement is dominant in 119860

0mode [20] Thus

1198600mode can be easier to be collected with air-coupled

ultrasonic transducers Meanwhile the wavelength of 1198600

mode is shorter than that of 1198780mode at the same frequency

When ultrasonic waves travel through air and hit theairplate interface at an angle both reflected and refractedwaves are produced After multiple reflections and modeconversion one or more Lamb wave modes are excited Inorder to excite Lambwave at a specific frequency the incidentangle should satisfy Snellrsquos law formulated by [21]

sin 120579 =119888air119888119901

(5)

where 120579 is the incident angle 119888air is the velocity of thewave propagating in air and 119888

119901is the phase velocity of the

Lamb wave As the velocity of air and the phase velocity ofLamb waves are known incident angle disperse curves ofLamb waves along ⟨110⟩ direction of monocrystalline siliconcan be obtained by solving (5) The results are shown inFigure 18 These curves help in optimizing the orientation ofthe transmitting and receiving air-coupled ultrasonic trans-ducers According to the results the theoretical coincidenceincident angle for 119860

0mode at 200 kHz should be 13∘

41 Air-Coupled Ultrasonic Experiment System The exper-imental set-up consists of a high power signal generator


Preamplifier

PC

Scanning system

Silicon waferAir-coupledtransducers

Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal

High power 50Ω termination

Figure 19 The diagram of air-coupled ultrasonic detection system

a high dB preamplifier high power 50Ω termination apersonal computer an oscilloscope and a scanning systemThe schematic diagram of experimental set-up is shown inFigure 19 The SNAP RAM-5000 (RITEC USA) ultrasonicmeasurement system is used to generate high power toneburst signals for excitation of the transmitting transducer(number 3) and to receive signals from the receiving trans-ducer (number 2) with its preamplifier The signal is thenacquired by an oscilloscope (DPO4054 Tektronix USA)with a sampling frequency of 50MHz A pair of transducerfixtures are used to hold and orient the air-coupled ultrasonictransducers at a special angle for exciting and receiving Lambwaves

42 Specimens Monocrystalline silicon shown in Figure 20is supplied in the form of plate with a crystal orientation of(001) whose diameter is 200mm and thickness is 725120583mand the size of the crack defect is 15mm times 05mm times 05mmwith the direction of ⟨110⟩

43 Experiments and Results The transmitting transducerand the receiving transducer are arranged in the same sideabove the silicon wafer surface with the fixed distance of80mm scanning along the direction of the crack detectionThe incident angle of transmitter 120579T kept equal to the receiver120579R is 13∘ The scanning distance is totally 50mm in stepof 2mm The excitation signal is also a 5-cycle 200 kHzsinusoidal tone burst modulated by a Hanning window Thesignals received at both the defect-free position and defectiveposition are shown in Figure 21

⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400

Figure 20 Sample ofmonocrystalline silicon and transducer set-up

In usual process of defect detection the amplitude ofdirect wave that transmits through the defect is used todescribe the presence and the size of the defects In thisexperiment the influence of the presence of cracks on theamplitude of signals is not that obvious So it is difficult todistinguish the location of the defect accurately based onamplitude characteristics

However when Lambwaves propagate through the cracknot only will the amplitude change but also the phase willshift or distort The correlation coefficient of the receivedsignal and the reference signal is calculated to extract the


minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)

Figure 21 Received signals for (a) defect-free position and (b) defective position

0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t

10 20 30 40 500Scan position (mm)

Result 1Result 2

Result 3

Figure 22 Correlation coefficient between reference signals andreception signals

influence of the crack on the signals [22] The rectangularwindow is used to intercept the received signals of Lambwave and the signal of defect-free position is used as ref-erence signal The correlation coefficients of all the receivedsignals and reference signal are calculated and establishedthe corresponding relationship with the scan position Theresults can be seen in Figure 22 The experiment has beenimplemented for 3 times All of the results show that thecorrelation coefficients of the received signals at defectiveposition are lower which means the waveforms have beendistorted when Lamb wave travels across the defect Thecorrelation coefficient of 06 is chosen as the threshold Thedefect position determined by thismethod is conformedwiththe actual defect position It proved that themethod is feasiblein monocrystalline silicon defect detection

5 Conclusion

In this research a new structure of air-based 1-3 piezoelectriccomposites is introduced The influence of the structuralparameters on the performance of air-based 1-3 piezoelectriccomposites has been investigated through finite elementanalysis According to the results of simulation the air-based1-3 piezoelectric composites and air-coupled transducersare fabricated with the PZT volume fraction 120593 = 40meanwhile the side length of PZT column 119886 = 1mm andthe thickness of the sensitive element ℎ = 10mm All of theair-coupled transducers can excite and receive the ultrasoundin air effectively and the signal-to-noise ratio (SNR) of directwave seems to be very well

Scanning method is used to detect the crack defect inthe monocrystalline silicon wafer by Lamb waves The directwave of119860

0mode is used to identify the defect Results reveal

that the location and size of the defect can be detected bycalculating the correlation coefficient of the received signalsand reference signals It proved that this method is feasible inmonocrystalline silicon defect detection

To sum up the 3D printed air-based 1-3 piezoelectriccomposites structures are appropriate to fabricate the air-coupled transducers They can both reduce the acousticimpedance and enhance the electromechanical conversionefficiency In future studies matchingbacking layer shouldbe taken into account to improve the performance of air-coupled transducers

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

The work in this paper is financially supported by theNational Natural Science Foundation of China (Grant


nos 11372016 and 51235001) and the Outstanding YoungResearcher Program from Organization Departmentof the CPC Beijing Municipal Committee (Grant no2014000020124G038)

References

[1] A Belyaev O Polupan W Dallas S Ostapenko D Hess andJ Wohlgemuth ldquoCrack detection and analyses using resonanceultrasonic vibrations in full-size crystalline silicon wafersrdquoApplied Physics Letters vol 88 no 11 Article ID 111907 2006

[2] G Yun K-M Kim Y Roh Y Min J-K Lee and Y H KimldquoComparison of slowness curves of Lamb wave with elasticmoduli and crystal structure in silicon wafersrdquo in Proceedingsof the IEEE International Ultrasonics Symposium (IUS rsquo13) pp1598ndash1601 IEEE Prague Czech Republic July 2013

[3] S-H Kee and J Zhu ldquoUsing air-coupled sensors to determinethe depth of a surface-breaking crack in concreterdquo Journal of theAcoustical Society of America vol 127 no 3 pp 1279ndash1287 2010

[4] O Balogun G D Cole R Huber D Chinn TWMurray and JB Spicer ldquoHigh-spatial-resolution sub-surface imaging using alaser-based acoustic microscopy techniquerdquo IEEE Transactionson Ultrasonics Ferroelectrics and Frequency Control vol 58 no1 pp 226ndash233 2011

[5] Z Zhou and D Wei ldquoProgress of air-coupled ultrasonic non-destructive testing technologyrdquo Chinese Journal of MechanicalEngineering vol 44 no 6 pp 10ndash14 2008

[6] H B Kichou J A Chavez A Turo J Salazar and M JGarcia-Hernandez ldquoLamb waves beam deviation due to smallinclination of the test structure in air-coupled ultrasonic NDTrdquoUltrasonics vol 44 pp e1077ndashe1082 2006

[7] I Y Solodov R Stoessel and G Busse ldquoMaterial characteriza-tion and NDE using focused slanted transmission mode of air-coupled ultrasoundrdquoResearch inNondestructive Evaluation vol15 no 2 pp 65ndash85 2004

[8] F Yan E Hauck T M Pera et al ldquoUltrasonic guided waveimaging of a composite plate with air-coupled transducersrdquo inReview of Progress in Quantitative Nondestructive Evaluationpp 1007ndash1012 AIP Publishing 2007

[9] S K Chakrapani M J Padiyar and K BalasubramaniamldquoCrack detection in full size Cz-silicon wafers using lambwave air coupled ultrasonic testing (LAC-UT)rdquo Journal ofNondestructive Evaluation vol 31 no 1 pp 46ndash55 2012

[10] Z Liu H Yu C He and B Wu ldquoDelamination damagedetection of laminated composite beams using air-coupledultrasonic transducersrdquo Science China Physics Mechanics andAstronomy vol 56 no 7 pp 1269ndash1279 2013

[11] R E Newnham D P Skinner and L E Cross ldquoConnectivityand piezoelectric-pyroelectric compositesrdquo Materials ResearchBulletin vol 13 no 5 pp 525ndash536 1978

[12] G Hayward and J Bennett ldquoAssessing the influence of pillaraspect ratio on the behavior of 1-3 connectivity compositetransducersrdquo IEEE Transactions on Ultrasonics Ferroelectricsand Frequency Control vol 43 no 1 pp 98ndash108 1996

[13] A-C Hladky-Hennion and J-N Decarpigny ldquoFinite elementmodeling of active periodic structures application to 1ndash3piezocompositesrdquo Journal of the Acoustical Society of Americavol 94 no 2 I pp 631ndash635 1993

[14] M Bhardwaj ldquoPiezoelectric transducer with gas matrixrdquoWO2004017369 A2 2007 2003

[15] W A Smith and B A Auld ldquoModeling 1-3 composite piezo-electrics thickness-mode oscillationsrdquo IEEE Transactions onUltrasonics Ferroelectrics and Frequency Control vol 38 no 1pp 40ndash47 1991

[16] T R Gururaja W A Schulze L E Cross et al ldquoResonantmodes of vibration in piezoelectric PZT-polymer compositeswith two dimensional periodicityrdquo Ferroelectrics vol 54 no 1pp 183ndash186 1984

[17] J L Rose ldquoA baseline and vision of ultrasonic guided waveinspection potentialrdquo Journal of Pressure Vessel Technology vol124 no 3 pp 273ndash282 2002

[18] M-K Song and K-Y Jhang ldquoCrack detection in single-crystalline silicon wafer using laser generated Lamb WaverdquoAdvances inMaterials Science and Engineering vol 2013 ArticleID 950791 6 pages 2013

[19] M-K Song and K-Y Jhang ldquoCrack detection in single-crystalline silicon wafer using laser generated Lamb waverdquoAdvances inMaterials Science and Engineering vol 2013 ArticleID 950791 6 pages 2013

[20] Z Su L Ye and Y Lu ldquoGuided Lamb waves for identificationof damage in composite structures a reviewrdquo Journal of Soundand Vibration vol 295 no 3ndash5 pp 753ndash780 2006

[21] M Castaings P Cawley R Farlow and G Hayward ldquoSinglesided inspection of composite materials using air coupledultrasoundrdquo Journal of Nondestructive Evaluation vol 17 no 1pp 37ndash45 1998

[22] R Cepel K C Ho B A Rinker D D Palmer Jr T P Lerch andS P Neal ldquoSpatial correlation coefficient images for ultrasonicdetectionrdquo IEEE Transactions on Ultrasonics Ferroelectrics andFrequency Control vol 54 no 9 pp 1841ndash1849 2007

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



the transducerair and airspecimen interfaces wheremost ofthe incident wave will be reflected [5] When the ultrasoundpasses through an interface only a proportion of it can becoupled into the next materialThis ldquoproportionrdquo depends onhow close the acoustic impedance of these two materials isThe acoustic impedance of traditional piezoelectric ceramicmaterials is almost (30sim40) times 106 Rayl but that of air is only420 Rayl So the proportion of the ultrasound that is coupledinto the air will be only 0003sim0005

The active materials 1-3 type piezoelectric compositescomposed of polymer (epoxy resin or polyurethane) andpiezoelectric ceramic can reduce the acoustic impedancesignificantly Hence the transmitted proportion (from trans-ducer to air) can be increased Generally the 1-3 typepiezoelectric composites possess the following attributes lowdensity low acoustic impedance wide bandwidth and highelectromechanical coupling coefficient Newnham et al [11]first put forward the concept of 1-3 piezoelectric compositesBased on their study extensive researches have been car-ried out Hayward and Bennett [12] analyzed the workingcharacteristic of 1-3 piezoelectric composite transducers byfinite element method Hladky-Hennion and Decarpigny[13] observed the influence of geometrical parameters on1-3 piezoelectric composites by establishing a cycle modelBhardwaj [14] firstly proposed the prototype of air-basedpiezoelectric composites sensors using honeycomb structureor foam material as the substrate to reduce the density andacoustic impedance

To sum up in this paper air-based 1-3 piezoelectriccomposites air-coupled transducer will be introduced andevaluated Firstly the structure of piezoelectric composites ismanipulated Secondly 3D finite element models are createdto analyze the performance of air-based 1-3 piezoelectriccomposites Then the transducers based on 1-3 piezoelectriccomposites are fabricated with the honeycomb structuresof resin which are produced by 3D printing Also theexcitation and reception performance are tested Finallythese transducers will be applied in the crack detection bygenerating and receiving Lamb waves

2 3D Simulations of1-3 Piezoelectric Composites

21 1-3 Piezoelectric Composites and Their Finite ElementModel (FEM) As shown in Figure 1 conventional 1-3 piezo-electric composites are composed of piezoelectric columnswhich are mounted inside the polymer parallelly and period-ically The structure can reduce the density and decrease theacoustic impedance effectively This will close the impedancebetween piezoelectric transducer and the air so as to let moreultrasound through

In order to reduce the acoustic impedance of the piezo-electric composites significantly air-based 1-3 piezoelectriccomposites should be induced The structure and compo-nents of air-based 1-3 piezoelectric composites are shown inFigure 2 Using honeycomb structure as a matrix of piezo-electric composites the piezoelectric columns are embeddedin the cellular structure The honeycomb structure acts as a


Polymer

Figure 1 Conventional 1-3 piezoelectric composites


Polymer

Air

Figure 2 Air-based 1-3 piezoelectric composites

skeleton to support the piezoelectric column However theair gap (instead of the filling polymer in Figure 1) reduces thedensity and the acoustic impedance efficiently Thus the airbecomes the main part of the composite matrix And this iswhere the ldquoair baserdquo comes from

According to 1-3 piezoelectric composites thickness-mode oscillation theory [15] the acoustic impedance of 1-3piezoelectric composites can be formulated by

119885 = (11988833120588)12

(1)

where 119885 11988833 and 120588 are the generalized acoustic impedance

elastic constants and density respectively 11988833

and 120588 of 1-3 piezoelectric composites are determined by the volumefraction and the original elastic constants and density of eachown phase Comparedwith the conventional 1-3 piezoelectriccomposites the air-based 1-3 piezoelectric composites usehoneycomb structure as a matrix which will inevitablyreduce the acoustic impedance For example when 120593 =

40 epoxy 30 and air 30 we can obtain the generalizedacoustic impedance which equals 128 times 107 kgsdotmminus2sdots whilethe conventional one equals 137 times 107 kgsdotmminus2sdots It shows a7 decreaseTherefore at the same PZT volume fraction theacoustic impedance of air-based 1-3 piezoelectric compositesis lower than that of epoxy-based 1-3 piezoelectric compos-ites



120588

kgm3119888 1010Nm2 119890 Cm2 120576120576

0

11988811

11988812

11988813

11988833

11988844

11988866

11989033

11989031

11989015

12057611

12057633

7500 126 795 841 117 23 235 233 minus65 17 1700 1470

ffs fpO

|Z|







119898are selected





1198702

119905=

120587

2

119891119904

119891119901

tan(120587

2

119891119901minus 119891119904

119891119901

) (2)

119876119898



119876119898=

1198912

119901

2120587119891119904 |119885| 119862

119879 (1198912119901minus 1198912119904) (3)






120588 kgm3 119888119879 ms 119888

119871 ms 120576120576

0

CY1301HY1300 1140 1140 2370 4











119898changes





Air


Polymer


1020

30 40 50 60

12m

m

12 mm



Kt

20 30 40 50 6010120593 ()

05

055

06

065

07

075

08







10

15

20

25

30

Qm

20 30 40 50 6010120593 ()










12 mm 152mm 22mm 252mm 32mm



Kt

05

055

06

065

07

075

08

2 4 6 8 100s (mm2)






119873 = 1198910sdot ℎ (4)


Qm

10

12

14

16

18

20

2 4 6 8 100s (mm2)











Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08



Qm

6 7 8 9 105h (mm)

10

15

20

25

30






f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)



Number 119891119904

119891119901









(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











120588

kgm3119888 1010Nm2 119890 Cm2 120576120576

0

11988811

11988812

11988813

11988833

11988844

11988866

11989033

11989031

11989015

12057611

12057633

7500 126 795 841 117 23 235 233 minus65 17 1700 1470

ffs fpO

|Z|







119898are selected





1198702

119905=

120587

2

119891119904

119891119901

tan(120587

2

119891119901minus 119891119904

119891119901

) (2)

119876119898



119876119898=

1198912

119901

2120587119891119904 |119885| 119862

119879 (1198912119901minus 1198912119904) (3)






120588 kgm3 119888119879 ms 119888

119871 ms 120576120576

0

CY1301HY1300 1140 1140 2370 4











119898changes





Air


Polymer


1020

30 40 50 60

12m

m

12 mm



Kt

20 30 40 50 6010120593 ()

05

055

06

065

07

075

08







10

15

20

25

30

Qm

20 30 40 50 6010120593 ()










12 mm 152mm 22mm 252mm 32mm



Kt

05

055

06

065

07

075

08

2 4 6 8 100s (mm2)






119873 = 1198910sdot ℎ (4)


Qm

10

12

14

16

18

20

2 4 6 8 100s (mm2)











Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08



Qm

6 7 8 9 105h (mm)

10

15

20

25

30






f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)



Number 119891119904

119891119901









(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Air


Polymer


1020

30 40 50 60

12m

m

12 mm



Kt

20 30 40 50 6010120593 ()

05

055

06

065

07

075

08







10

15

20

25

30

Qm

20 30 40 50 6010120593 ()










12 mm 152mm 22mm 252mm 32mm



Kt

05

055

06

065

07

075

08

2 4 6 8 100s (mm2)






119873 = 1198910sdot ℎ (4)


Qm

10

12

14

16

18

20

2 4 6 8 100s (mm2)











Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08



Qm

6 7 8 9 105h (mm)

10

15

20

25

30






f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)



Number 119891119904

119891119901









(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










12 mm 152mm 22mm 252mm 32mm



Kt

05

055

06

065

07

075

08

2 4 6 8 100s (mm2)






119873 = 1198910sdot ℎ (4)


Qm

10

12

14

16

18

20

2 4 6 8 100s (mm2)











Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08



Qm

6 7 8 9 105h (mm)

10

15

20

25

30






f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)



Number 119891119904

119891119901









(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Kt

6 7 8 9 105h (mm)

05

055

06

065

07

075

08



Qm

6 7 8 9 105h (mm)

10

15

20

25

30






f0

(kH

z)

150

200

250

300

350

400

6 7 8 9 105h (mm)



Number 119891119904

119891119901









(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a)


(b)



60

70

80

90

100

110

Impe

danc

eZ(Ω

)

(a)

60

70

80

90

100

110Im

peda

nceZ

(Ω)


(b)

60

70

80

90

100

110

Impe

danc

eZ(Ω

)


(c)



T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










T R

80mm


100 150 200 250 300 350

024

A (m

V)







Time t (120583s)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2

024

A (m

V)

minus4minus2






0 01 02 03 040

10

20

30

40

Inci

dent

angl

e120579(∘

)

A0

S0








0


0mode [20] Thus





sin 120579 =119888air119888119901

(5)







Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Preamplifier

PC

Scanning system


Rotation platform

z

yx

120579

Receiverinput

Highpoweroutput

Outputmonitor

Receivermonitor

RITEC RAM-5000

Oscilloscope

Channels

Receipt signal

Excitation signal






⟨110⟩ ⟨100⟩

⟨110⟩

80mm15mm15mm

Crack defect

Scanning

50mm

R T

distance

R998400 T998400





minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










minus4

minus2

0

2

4A

mpl

itude

(mV

)

80 100 120 140 160 18060Time t (120583s)

(a)

0

80 100 120 140 160 18060Time t (120583s)

minus4

minus2

0

2

4

Am

plitu

de (m

V)

(b)


0

02

04

06

08

1

Cor

relat

ion

coeffi

cien

t


Result 1Result 2

Result 3



5 Conclusion






Competing Interests


Acknowledgments




References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











References

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article Design and Fabrication of Air-Based 1-3 ...downloads.hindawi.com/journals/js/2016/4982616.pdf · Design and Fabrication of Air-Based 1-3 Piezoelectric Composite Transducer