34-Cavanaugh J. M.-quasi static frontal loading of the thorax of human cadavers and the hybrid III dummy.pdf

7/30/2019 34-Cavanaugh J. M.-quasi static frontal loading of the thorax of human cadavers and the hybrid III dummy.pdf

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Quasi-stat ic Frontal Loading of the Thoraxof Human Cadavers and the Hybrid I I I DummyJ.M. Cavanaugh, K. Jepsen, A.I .King

Wayne State UniversityBioengineering CenterDetroi t , Michigan

Presented a t the 16th Annual International Workshop onHuman Subjects for Biomechanical ResearchAtlanta, GeorgiaOctober 16, 1988

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Quasi-stat ic Frontal Loading of the Thoraxof Human Cadavers and the Hybrid I I I DummyJ.M. Cavanaugh, K. J ep sen, A .I .K ing

ABSTRACTThe purpose o f th is study was to determine quasis ta t ica l ly th e s t i f fness

aad deformation of theJhuman thorax a t three sternum and three r ib locat ions.Two unembalmed human cadavers and the Hybrid III Dummy were loaded quasi-s ta t ica l ly in an A-P (an te r ior-pos te r ior ) d i rec t ion on the anter ior su rfa ce o fthe thorax a t s ix different locat ions; upper, middle and lower sternum, andupp er, m id dle , and lower r ight r ibs (Figs. lA & lB). The A-P deformation ofthe thorax was simultaneously measured with l inear pots a t these r ib andsternum locat ions during th e loa ding. The resul ts of these tes ts show: 1)using a 25.4 mm (one inch) s t roke, the s t i f fness of the human thorax was 6 to10 N/mm a t the sternum and' 3.5 to 6 N/mm a t the ribs, 2) with the same stroketh e s t i f fness of the Hybrid I I I was 26-44 N/mm at_ the sternum and 32-73 N/mma t the r ibs , 3) the mid-sternum force-deflect ion curves for the c a d a v ~ r f i t asecond order l inear equation, and were comparable to those obtained in l ivesubj ects in a study, by Tsi t l ik e t a1 (1) using CPR techniques, 4) each loadwas repeated with the ra te of loading increased from 1.7 to 102 N/mm (0.067 to4.0 in/s ) , and thus far the increased loading ra te has not shown consistentincrease in s t i f fness or energy diss ipa t ion.METHODOLOGY

The sub jec t was mounted in a supine pos i t io n in a suppor t framef ab ri ca te d o f Un is tr ut and aluminum pla te (Fig. 2). The subject was loaded a teach of s ix load locat ions wi th an Instron Kodel 1321 tes t ing machine, inwhich a t r iax ia l load ce l l was incorporated into the loa ding head. Deflectionof the ches t and o f the loading head were measured with Novotechnik

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potent iometers , model # 75, which have elastomeric damped wipers , 75 rom s t rokerange and 0.002 mm resolut ion. Loads were t r ansfe r red from the Ins t ronac tua tor to the sub jec t v ia a 6" I beam.

Two support condi t ions were s tudied: 1) In the f i r s t , only the sub jec t ' sspine was supported a t the thorac ic , lumbar and s ac ra l le ve ls . T his allow edthe p o s te ri or p or ti on of the r ib cage to d e fl ec t p o st er io rl y as loads wereappl ied an te r io r ly . Ribs def lec t ion was measured on the l e f t s ide only assymmetry was assumed with mid-line s te rna l l oa di ng ( Fig . 3A). 2) In the secondsupport condi t ion, the sub jec t ' s spine and pos te r io r r ibs were supported ,

loads were appl ied a t both the sternum and the r ibs , and def lec t ions wererecorded a t both l e f t an d r igh t r ibs as wel l as the s ternum. In t h i s secondsupport condi t ion the pos te r io r r ibs were supported so t h a t when the r ibs wereloaded, the ches t would no t ro ta te under eccent r ic loading (Fig . 3B). The r ibswere s up po rte d c on ti nu ou sl y on gimbled p la tes mounted to threaded rodsa t t ached to two 51 x 51 mID (2 x 2 i n , , ~ ' h ) s t e e l box beams running pa r a l l e l toand b i l a t e r a l to the spine. These r ib support beams were placed approximate ly70 mm l a t e r a l to midline.

Table 1 shows the t e s t s run to date.TABLE 1

TEST NO. TEST DATE TEST SUBJECT RUN NOS.AATDI 2-22-88 HYBRID I I I 1-11AATD2 2-23-88 * CAD. 11986 1-10AATD3 4-01-88 HYBRID I I I Tl -T l l , 1-15AATD4 4-25-88 HYBRID I I I TI-T8, 1-18AATD5 7-07-88 11 CAD. 1/115 1-30*CAD. 11986 : 29 yr old male, h t: 1.73 ID, wt: 70.3 kgIICAD . 1/115 : 57 y r o ld male, h t: 1.79 m, wt: 57.6 kg

SUPPORT CONDITIONSPINESPINE, RIBSSPINESPINE, RIBSSPINE, RIBS

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In i n i t i a l t e s t s (AATD1, AATD2) , the subjects were used to evaluate theapparatus an d to determine prac t i ca l loading r a tes . Afte r some modif icat ionsto the apparatus, the dummy and the second cadaver were then run underiden t i ca l support condit ions with 25.4 rom s t rokes appl ied to the sternum an dr ibs a t loading r a tes of 1.7 an d 102 mm/s (0.067 an d 4 in / s ) (AATD3, 4, an d5). Two-inch strokes were attempted bu t caused r ib f rac ture and were thereforediscontinued. Upper and mid-sternum s t i f fness da ta is presented fo r bothcadaveric t e s t s (AATD2 and AATDS). Other cadaveric s t i f fness and def lec t ionda ta i s presented for AATDS only, as th i s can be di rec t ly compared to theHybrid I I I da ta in t e s t s AATD3 an d AATD4.

RESULTSThe resu l t s of these s tu d ie s i nd ic at e t he f ol low ing:

THORACIC STIFFNESS(See Tables 2 an d 3)

1) The human thorax i s s t i f f e r under s te rna l lo ad ing than under r ib loading(sternum: 5.9-11.4 N/mm vs . r ib s : 3.4-5.8 N/mm). The Hybrid I I I thorax isless s t i f f under s t e rna l lo ad in g th an r ib loading (sternum: 26-44 N/mm vs.r i b s : 32-73 N/mm). Under s t e r n a l load ing , th e Hybr id I I I dummy i sapproximately three to f ive times as s t i f f as the cadaver, and under r ibloading, s ix to fourteen t imes as s t i f f .

2) Increas ing the loading ra te from 1 .7 to 102 mm/s (a s ix ty-fo ld increase)d id not cons is ten t ly r e su l t in an increase in thoracic s t i f fness of thecadaver bu t d id so in the dummy.

3) The loading por tion of the force -def lec t ion curve of the human cadavercould usua l ly be fit to a second-order non- l inear curve, while the HybridI I I reponse was almost l inear . The cadaveric response also showed more

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energy absorpt ion . (See Figures 4A-4C). The mid-s te rna l , second order curvefo r the AATD2 and AATDS cadavers i s c lose to the a ve ra ge c urv e obtained byTs i t l i k e t a l (1) in perfoming CPR on eleven l ive human sub jec t s (Fig . 5).

THORACIC DEFORMATION(See Tables 4 an d 5)

1) Under s t e r na l loading the A-P r ib def lec t ion of the human cadaver was 6 to63% of the appl ied s te rna l s t roke , while the r ib def lec t ion of the HybridI I I dummy was 27 to 60% of the a pp li ed s tr ok e .

2) Under r ib loading, the r ibs con t ra la te ra l to the s ide of loading in thehuman cadaver had an A-P del fec t ion of 0 to 14% of the appl ied s t roke , an din the Hybrid I I I dummy 9 to 31 % of the a pp lie d s tr o ke .

3) Under s t e r na l load ing , the pos te r io r r ibs o f the cadavers def lec ted lessthar 5% o f the a pp lie d s tr ok e an d in the dummy 8 to 10%.

CONCLUSIONSIn c on clu sio n, the human c ad av er ic th or ax i s much more compl iant than

t h a t o f the Hybrid I I I under quas i - s ta t i c loading. It i s assumed tha t much ofth i s i s du e to the di f fe rence in mater ia l proper t ies of the r ibs of the humanske le ton vs . the Hybrid I I I . It i s a l so hypothesized tha t the mater ia lp rop er ties of the c os ta l c ar t i la ge con t r ibu te grea t ly to the l e s s s t i f fresponse seen in the human cadaver . Prel iminary f in i te element ana lys is by agraduate s tuden t Shij ie Ruan of a two-dimensional closed hoop ac t ing as acompression r ing with a 4" length o f c ar ti la ge n ou s t i s sue inser ted on e i t h e rs ide o f the sternum d ec re ase d th e s t i f fness from 20.2 N/mm to 3 .1 N/mm whencompared to a closed hoop with bone mater ia l proper t ies a t the cos ta lca r t i l age loca t ion. The lack of a car t i laginous r ib mater ia l in the Hybrid I I Ian te r io r ches t wall probably con t r ibu tes to the s t i f f e r response and moreuniform r ib def lec t ion seen in the Hybrid I I I .

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REFERENCES1. Ts i t l i k JE, Weisfe ld t ML, Chandra N, Effron MB, Halperin HR, Levin HR:E la st ic p ro p er tie s of the human ches t during cardiopulmonary resusci ta t ion .Cr i t i ca l Care Medi ci ne 11:685-692, 1983.

ACKNOWLEDGEMENTSWe wish to acknowledge Lawrence W. Schneider of the U nivers ity of

Michigan Transportat ion Research Ins t i tu t e fo r h is va luable input into thet e s t methodology. This pro jec t was supported by NHTSA grants DTNH22-83-C-7019an d DTNH22-83-C-700S.

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.. . nat

, \ ~ j l r - . r - - IOtb rib

Figure LA. Load locat ions (rectangles) , and potentiometer locat ions (dots) asused in th e c ad av er ic chest compression t es t s . The sternum was also loaded a tmid-sternum (rectangle not shown for c la r i ty) .

URus-URRIB NO. R16HT LEn

U5=UPPER STEIIUN"5alIIDSJEIIIJJtlS-LOVER S T E R ~UI-UPPER RIB"R-NID-RIBlR-lOMER RIB2 : -

3

56

. . . . . . "R: "R"5._._------_._._-----: --------------------I---_.. ----_ .. _-----.,

---tR-lSlR -

HYBRID III: FRONT RIB P o T E N T I ~ E T E R LOCATIONSARE AS SHaMJI.(LOAD LOCATIONS ARE AT THE 3 STERNU" AND3 RIGHT RIB POTENTID"ETER lOCATIONS).

HYBRID III: BACK 118 P O T E N T I ~ T R LOCATIONS:NOME IN MTD4.AT LEFT U R, "R, AND lR IN AATD3.

Fig. lB. The Hybrid I I I load and potentiometer locat ions were similar : f i r s t ,th i rd and s ix th r ibs and upper, middle, and lower s te rnum .

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! s r ~ o L . 1

1IIIII~

- r-T =rI I I

II' ~I .

I' .d

~(J \

'1co jJ

t,

P.\.rrt'\

Figure 2. Unistrut support frame, Instron tes t ing machine, and loading head.

(Dimensions in inches)

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Figure 3A. Schematic chest cross-sect ion showing spine s uppo rt o nly .

Figure 3B. Schematic ches t c ro s s - s ec t i on showing r ib p lu s sp ine su pp ort .

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..

o. - - 0:t 0to

or- - 0* (\ J

~ OL O

~ OZ ', - - ,N

25.05.0(m m)5 .0DEFLFigure 4b

WlJ.J / ~ UU ' ~ ~~ O OO . .. ,0o LL ' ,LL _ a .. --.....-----rl- - . - - . . . ~ . '--. - i r - - - : - - - _ I --

I _ -5.0-5 .0 15.0 25.0Figure 4a 0EFL (mm).....eN

o.- - 0 O .to

Figures 4A. 4B. and 4C. Mid-sternal force-deflectioncurves of two cadaver runs and one Hybrid I I I run.4A. Force-deflection curve of AATD2. Run 114 (Cad.#986). Max Fz - 345.0 N. max deflection - 31.3 mrn4B. Force -deflec t ion curve of AATD5, Run IlIA (Cad.#115). Max Fz - 247.7 N, max deflection - 26.1 mm.4C. Force -deflec t ion curve of AATD3. Run 1)2 (HybridI I I ) . Max Fz - 794.0 N. max deflection - 24.26 mm.

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Figure 5 FORCE-DEFLECTION COMPARISONWSU CADAVER VS. TSITLIK ET AL

Equation of Tsit l ik et a1F= 5.49 D + 1.08 D2

Force in NewtonsD= Deflections in rom

260

240220200180160~ r--..Z

'- / 140wu 120alL100806040200

0

RUNS 3 & 4

4-

+

8 12 16DEFLECTION (MM)MTD5: RUNS 1 & 1A

20 24-() TSITLIK


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TABLE 2THORACIC STIFFNESS FOR CADAVER TESTS AAiD2 AATD5

USl 0.067 /ltS1 0.06i LS1 a.06i~ ~ - - ~ - - - - - ~ - - - ~ - - - - - ~ - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - -TEST NAME AATD2 &5 AATD5 AATD2 &5 AATD5 AATD5 AATD5RUN NO. 2:5,6 S:5,5A 112:3,4S:1,lA R13f 7 15

SUBJECT CAD 986 ~ 1 1 5 CAD 115 CAD 115 CAD 115 CAD 115 CAD 115BACK RIB SUPPORT? NO YES NO YES NO YES~ A X . FORCE (N) 230.59 278.11 247.96 275.10 192.78 152.47

DEFL. (11l'!) 25.17 24.51 25.36 25.91 25.03 26.04STIFFNESS (N/MM) 9.16 11.35 9.78 la.S2 .. "1 ,.l.i J.oc

USl 4.0 MS l 4.0 LSl 4.0TEST NAME A A T O ~ AATDS AATD5 AATD5 AATDS AATDSRUN NO. 6 12 2,2A 14 8 16SUBJECT CAD 115 CAD 115 CAD 115 CAD 115 CAD 115 CAD 115BACK RIB SUPPORT? NO YES NO YES NO YES

~ A X . FORCE (N) 182.50 267.78 212.16 287. '31 157.51 154.95MAX DEFL. ( ~ ! - ! ) 24.i3 24.77 24.67 25.68 25.02 26.22STlrFNESS (N/"") 7.38 11.81 8.60 8.11 6.32 S. '31

UR1 0.367 URi 4.a r1Rl 0.067 MR l 4.0 LRI 3.067 LRI 4.0-_......_-_ .._- - - - - - - - ~ - - ----------- ------ .._-- ---------- ----------TEST NAME AATD5 AATD5 AATD5 AATD5 AATDS AATD5RUN NO. 2S 26 21 1')1') 17 18

SUBJECT CAD 115 CAD 115 CAD 115 CAD 115 CAD 115 CAD 115BACK R!B SUPPORT? YES YES YES YES YES YESMAX. FORCE o-n 147.79 152.53 136.67 136.26 89.01 33.42DEFL. (fit"') 26.25 26.20 25.36 25.57 25.08 26.04STIFFNESS ( N / " ~ ) 5.63 5.83 5.39 5.33 3.42 ".... "'oJ

fR13: rORCE SHOWN FOR R13 HAS BEEN INCREASED BY(AVa MA X FORCE IN RUNS 1,lA)i(MAX FORCE IN RUN R l ) ~RUNS 1 lA WERE BEFORE RIB rRACTUREi Rl R13 WERE AFTER RIB FRACTURE.

UR=UPPER RIBMR=J'fID RIBLR=LOWER RIB

CODE:USl 0.067=UPPER STERNUM LOADED TO 1" STROKE AT ARATE OF 3.06i ' /SUS1 4.0 =UP ER STERNUM OADED TO 1 STROKE AT ARATE OF 4.0ETC.

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TABLE 3THORACrC STIFFNESS HYBRID IIr TESTS AATD3 AATD4

USl 0.067 0.06i LS1 0.067~ - - - - - - - - - - - - - - - - - - - ~ - - ----------------------- -----------------------

TEST NAME AATD3 AATD4 AATD3 AATD4 AATD3 AATD4RUN NO. b 11 .., 7 10 15SUBJECT HYB III HYB III HYB III HYB III HYB III HYB IIIBACK RIB SUPPORT? NO YES NO YES NO YES"AX. FORCE (N) 685.28 735.28 794.00 874.08 688.25 668.16MAX DEfl. (11M) 25.40 25.40 25.40 25.40 25.40 25.40STIfFNESS (N/MM) 26.98 28.95 31.26 34.41 27.10 26.31

US! 4.0 "51 4.0 LSI 4.0----------------------- ----------------------- - - - - - - - - - - - - - - - - - - ~ - - - -

TEST NAME AATD3 AATD4 AATD3 AATD4 AATD3 AATD4RUN NO. 7 12 4 8 12 16SUBJECT HYB III HYB III HYB III HYB III HYB III HYB IIIBACK RIB SUPPORT? NO YES NO YES NO YES

~ A X . fORCE (N) 807.87 897.57 1004.85 1125.28 765.24 844.27MA X DEFL. (MM) 25.40 25.40 25.40 :5.40 25.40 25.40STIFFNESS (N/MM) 31.81 35.34 39.56 44.31 30.13 33.:4

UR I 0.C67 URI 4.0 MRI 0.0bi MR l 4.0 LRI 0.067 LRl.......... _-_ .... ....._------- ~ - - - - _ - . _ - - ----------- ------- ....- ----- ..----TEST NAME AATD4 AATD4 AATD4 AATD4 AATD4 AATD4RUN NO. 3 4 1 ., t" 6\.i

SUBJECT HYB.l!I HYB.III HYB.IIl HYB.III HYB.III HYB.IIIBACK RIB SUPPORT? YES YES YES YES YES YESMAX. FORCE (N) 805.50 831.54 1426.94 1863.06 1124.50 1504.48DEF1. (l'tM) 25.40 25.40 25.40 25.40 25.40 25.40STIFFNESS (NiMM) 31.72 32.74 56.18 ., '" "'t" 44.27 59.23J . ' ; ; ' ;

US=UPPER STERNUM UR=UPPER RIB~ S = M I D S i E R N U ~ ~ R = M I D RIBLS=LOWER STERNUM LR=lOWER RIB

CODE:US1 B.067=UPPER STERNUM LOADED TO II STROKE AT ARATE or 0.067'!5U51 4.0 =UPPER STERNUM LOADED TO 1 STROKE AT ARATE or 4.0 "ISETC.

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TABLE 4THORACIC DEFORftATION FOR CADAVER TEST AATD5

STERNU" LOADIN6.LOADING RATE: 0.067 INIS"AX STROKE: 1.0 INCHSUPPORT CONDITIONS: SPINE SUPPORTED.

POSTERIOR RIBS SUPPORTED BILATERALLY.LOAD LOCATION IS SHOMN ABOVE EACH TABLE.DEFLECTIONS ARE SHOWN IN IN CH ES AT EACH LOCATION.LOAD POINT: UPPER STERNU" LOAD POINT: "In STERNU" LOAD POINT: LOMER STERNU"NO. CADAVERS: 1 NO . CADAVERS: 1 NO. CADAVERS: 1TESTS: AATD5: 11 TESTS: AATD5: 13 TESTS: AATDS: 15RI6HT RIBS STERNU" LEFT RIBS RI6HT RIBS STERNU" LEFT RIBS RIGHT RIBS STERHU" LEFT---------- --------- -.--------- ---------- --------- ----------- ---------- --------- ------2: 0.50 U: 1.00 2: 0.48 2: ---- U: ---- 2: 0.37 2: 0.15 U: 0.16 2:

ft: ---- 'I: 1.00 /It: ----5: 0.18 L: 0.35 5: 0.20 5: 0.31 L: ---- 5: 0.30 s: 0.63 L: 1. 00 5:8: 0.06 8: 0.07 s: 0.18 B: 0.15 B: 0.57 B:

RIB LOADIN6.LOAD IN6 RATE : 0.067 INIS"AI STROKE: 1.0 INCHSUPPORT CONDITIONS: SPINE SUPPORTED.

POSTERIOR RIBS SUPPORTED BILATERALLY.LOAD LOCATION IS SHONN ABOVE EACH TABLE.DEFLECTIONS ARE SHOWN IN IN CH ES AT EACH LOCATION.LOAD POINT: RI6HT 2ND RIB LOAD POINT: RIGHT 5TH RIB LOAD POINT: RI6HT 8TH RIBNO. CADAVERS: 1 NO . CADAVERS: 1 NO. CADAVERS : 1TESTS: AATD5: 25 TESTS: AATD5: 21 TESTS: AATD5: 17RIGHT RIBS STERNU" lEFT RIBS RI6HT RIBS STERNU" LEFT RIBS RIGHT RIBS STERNU" LEFT-------.... --------- ----------- ---------- --------- ------._--- ---------- --._----- -----2: 1.00 U: 0.31 2: 0.13 2: 0.08 U: 0.04 2: 0.01 2: 0.00 U: 0.00 2:

": ---- ft: ---- 'h ----5: 0.22 L: 0.24 5: 0.00 5: 1.00 L: 0.49 5: 0.0' 5: 0.42 L: 0.42 5:8: 0.05 8: 0.01 s: 0.40 8: 0.12 8: 1.00 8:

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1: 0.27 U: 0.41 1: 0.31RIGHT RIBS STERNU,. LEFT RIB

LOAD POINT: LDMER STERNU,.HYBRID IIITESTS: AATD4: IS

1: 0.43 U: 0.33 1: 0.10RIGHT RIBS STERNU" LEFT RIB

LOAD POINT: RIGHT 6TH RIBHYBRID IIITESTS: AATD4: S

TABLE 5THORACIC DEFOR"ATION FOR HYBRID III TEST AATD4

STERNU,. LOADING.LOADINS RATE: 0.067 INIS"AX STROKE: 1.0 INCHSUPPORT CONDITIONS: SPINE SUPPORTED.POSTERIOR RIBS SUPPORTED BILATERALLY.

LOAD LOCATION IS SHOWN ABOVE EACH TABLE.DEFLECTIONS ARE SHOWN IN INCHES AT EACH LOCATION.

LOAD POINT: UPPER STERNUft LOAD POINT: "10 STERNU"HYBRID III HYBRID IIITESTS: AATD4: 11 TESTS: MTD4: 7RIGHT RIBS STERNU" LEFT RIBS RISHT RIBS STERNU,. LEFT RIBS--,.-----_. -_......... _- ----------- ---------- --------- -----------1: 0.58 U: 1.0 1: 0.60 1: 0.56 1: 0.58

3: 0.44 3: 0.48 3: 0.S4 ": 1.0 3: 0.556: 0.32 L: 0.52 6: 0.34 6: 0.53 6: 0.59

RIB LOADIN6.LOADING RATE: 0.067 INIS"AX STROKE: 1.0 INCHSUPPORT CONDITIONS: SPINE SUPPORTED.POSTERIOR RIBS SUPPORTED BILATERAllY.LOAD LOCATION IS SHOWN ABOVE EACH TABLE.

DEFLECTIONS ARE SHOWN IN INCHES AT EACH LOCATION.LOAD POINT: RIGHT 1ST RIB LOAD POINT: RIGHT 3RD RIBHYBRID III HYBRID IIITESTS: AATD4: 3 TESTS: AAiD4: 7RIGHT RIBS STERNUft LEFT RIBS RIGHT RIBS STERNU,. LEFT RIBS

.._-_ .._- _.------- ----------- ---------- --------- -----------1: 1.0 U: 0.52 1: 0.31 1: 0.80 U: 0.67 1: 0.293: O.SO 3: 0.19 3: 1.0 3: 0.246: 0.33 l: 0.32 6: 0.09 6: 0.74 L: 0.68 6: 0.25

18

3: 0.346: 0.47

3: 0.566: 1.0

L: 1.0

l : 0.67

3: 0.386: 0.53

3: 0.156: 0.26


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DISCUSSIONPAPER: Quasi -S ta t i c Fron ta l Loading to th e Thorax of Cadaversand Hybrid I I I DummySPEAKER: J .M. Cavanaugh, Wayne Sta t e Univer s i tyQ: Ted Kennedy, Consul t ing Engineer

I don ' t t h i nk you de te rmined dur ing your t e s t i n g , bu t i s itconce ivab le , wi th an a i r bag fo r load ing in th e f r on t a l a rea ,to ge t r ib f r a ctu re s in the back wi thou t any in the f ron t?You have good d i s t r i bu t i on o f th e load ing in th e f ron t , andac tua l ly f lex th e r i b s .A: Cavanaugh

I haven ' t been involved in any dynamic pendu lum type t e s t s butI don ' t t h i nk they showed po s t e r i o r r ib f r ac tu res . Maybe somebodye l s e could v er if y th at?A: Guy Nushol tz , Chrys le r

I ' v e seen f ra ctu re s in th e back very near th e sp ine withimpac ts to th e f ron t . But normally you a l so have f r ac tu resin th e f ron t as we l l , and you have to h i t them f a i r l y s eve r e ly .Q: Guy Nushol tz , Chrys le r

You showed a curve where you sa id th e response was nonl inea r .Did perhaps p a r t of th e cadaver y ie ld o r f r ac tu re and t h a t was th er e s u l t . Did you check t h a t ?A: With one inch s t roke s we d i dn ' t g e t r ib f r ac tu re . During s t rokeswe heard r ib f r ac tu re and ve r i f i ed t h a t w ith a uto ps y. I th ink fo rthese cases which were one i nch , it wasn ' t due to f r a c t u r e .Q: It could have been some hys t e re s i s no t re la te d to a f r ac tu rephenomenon? It looked p re tty l in e ar when it went s t r a i gh t ou t .It d i dn ' t seem to show any i nd i c a t i on of y i e l d i ng .A: Well t h e re were two up t h e re I d id n 't r e al ly concent r a te toomuch on th e f i r s t one . The f i r s t one was more non l inea r t han th esecond one. The second orde r curve i s p re t t y f l a t : comparable towhat has "been seen in l i v e volun tee rs .Q: Are you a t t r i bu t i ng non l i nea r i t y to th e f a c t t h a t it doesn ' tcome back down th e r i s e l i n e? It looked l i k e a s t r a i gh tl i ne to me. It looked l i n e a r on th e r i s e and then it had ahys t e re s i s coming back .

A: We ran a l i n e a r and non l inea r fit th rough th e r i s i ng por t ion

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o f th e curve and a nonl inea r fit be t t e r . The l i n e a r fit wasstill c lo se . The c o rr e la ti on c o e f fi c ie n t was qu i t e good fo r th el i n e a r fit bu t qu i t e a b i t be t t e r fo r th e n on lin ea r fit. Forth e unloading por t ion , which we haven ' t checked, I t h ink a t h i rd orde requat ion looks l i k e it might fit the unloading por t ion be t t e r thanth e second order equa t ion .

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34-Cavanaugh J. M.-quasi static frontal loading of the thorax of human cadavers and the hybrid III dummy.pdf