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A NEW LEGFORM IMPACTOR FOR EVALUATION OF CAR AGGRESSIVENESS IN CAR-PEDESTRIAN ACCIDENTS

Adam Wittek, Atsuhiro Konosu, Yasuhiro Matsui, Hirotoshi IshikawaJapan Automobile Research InstituteAkira SasakiJapan Automobile Manufacturers AssociationJapanTariq Shams, Jason McDonaldGESAC Inc.United StatesPaper Number 184

ABSTRACT

The goal of the present study was to develop a newlegform impactor that accurately represents both theimpact force (i.e., force between the leg and impactingmass) and leg kinematics in lateral impacts simulatingcar-pedestrian accidents. In its development we utilizedthe knee joint of the pedestrian dummy called Polar-2(HONDA R&D) in which the cruciate and collateralligaments are represented by means of springs andcables, the geometry of the femoral condyles issimplified using ellipsoidal surfaces, and the tibialmeniscus is represented by an elastomeric pad.

The impactor was evaluated by comparing itsresponses with published experimental results obtainedusing postmortem human subjects (PMHS). Theevaluation was done under two conditions: 1) impactpoint near the ankle area (bending tests), and 2) impactpoint 84 mm below the knee joint centre (shearingtests). Two impact speeds were used: 5.56 m/s and11.11 m/s.

The responses of our impactor were reasonablyclose to those observed in the experiments usingPMHS in terms of both impact force and leg shearingdisplacement (i.e., relative displacement between theleg and thigh at the knee joint level in a lateraldirection). In the shearing tests, the peak values of legshearing displacement were greater than 30 mm.

INTRODUCTION

In non-fatal car-pedestrian accidents, lower extremitiesaccount for around 40% of the most commonly injuredbody parts (ITARDA, 1996). These injuries often leadto long-term or permanent disability, and theirreduction is one of the priority items in traffic safetystrategy. An important element of such strategy is todecrease the aggressiveness of the components of a carfront. A commonly used method of evaluation of suchaggressiveness is subsystem testing using legformimpactors. Several such impactors have beendeveloped so far. The most widely utilized are those ofthe Transport Research Laboratory (TRL impactor)

(EEVC, 1998) and the Japan Automobile ResearchInstitute (JARI-1 impactor) (Matsui et al., 1999). TheTRL impactor has already been used in the EuropeanNew Car Assessment Program (Euro NCAP) and hasbeen accepted as a prototype test device in a workingdraft of the European Regulations (EEVC, 1998).However, the recent study by Matsui et al. (1999) hasindicated important differences between the responsesof both TRL and JARI-1 impactors and the behavior ofhuman lower extremities. According to this study,these impactors exhibit much lower peak values ofrelative displacement between the leg and thigh at theknee joint level in a lateral direction (i.e., leg shearingdisplacement) than those observed in experimentsconducted on postmortem human subjects (PMHS).This leads to a question about the validity of the TRLand JARI-1 impactors in evaluations of car frontaggressiveness, since the leg shearing displacement isoften used as an indicator of injury risk to the kneejoint ligaments.

Therefore, the goals of the present study are asfollows. First, to develop a new legform impactor(referred to as the new JARI impactor) that accuratelyrepresents both the impact force and leg kinematics inlateral impacts simulating car-pedestrian accidents.Second, to evaluate the biofidelity of this newlydeveloped impactor by comparison of its responseswith the results of PMHS experiments. Third, tocompare biofidelity of the TRL and new JARIimpactors.

METHODS

Development of New JARI Legform Impactor

Knee Joint It is likely that the lack of biofidelity ofthe TRL and JARI-1 impactors reported by Matsui etal. (1999) results from the too simplified structure andgeometry of knee joints of these impactors. None ofthem represents the knee articular surfaces, and in bothof them the ligaments are simplified by means of metalbars. In consequence, in both TRL and JARI-1impactors, the relative displacement between the leg

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and thigh in a lateral direction is too stronglyconstrained.

For this reason, in the new JARI impactor, thehuman knee joint structure and geometry were moreaccurately represented. This was done by application ofthe knee joint of the pedestrian dummy POLAR-2developed by GESAC and HONDA R&D (Artis et al.,2000). In this joint, the femoral condyles are simplifiedby means of ellipsoidal surfaces with a left/rightsymmetry, and the tibial meniscus is represented bymeans of a urethane pad (Figures 1 and 2a). To assurethe durability of this pad, its thickness was arranged toexceed that of the human meniscus. For the samereason, the intercondylar eminence was made broaderthan its human counterpart. In contrast to the TRL andJARI-1 impactors, the knee joint ligaments in the newJARI impactor are represented by cables connected to asystem of non-linear springs and rubber tubes (Figures1 and 2a). The bending stiffness of these cables is verylow, and they can constrain the leg motion onlythrough their tensile forces. These forces aredetermined by the damping and force-elongationproperties of the system of springs and rubber tubes asdescribed by Artis et al. (2000). Another importantfeature of the spring and cable representation of theligaments is that these elements are reusable in contrast

to the metal bars in the TRL and JARI-1 leg impactorswhich have to be replaced after a test.

Leg and Thigh As with the TRL and JARI-1impactors, the leg and thigh shafts in the new JARIimpactor are made of very stiff aluminum tubes. Theywere designed according to the geometrical andmass/inertia specifications indicated in a draft proposalof the ISO standard (ISO, 1996) (Figure 2).

Figure 1. A front oblique view of the knee joint ofthe new JARI impactor.

a) b)

Figure 2. The new JARI legform impactor: a) Front view; b) Position of gravity centers (COG) of theimpactor leg and thigh. mL and mT are masses of the impactor leg and thigh, respectively. mL and mT includethe impactor foam and “skin” (for explanation see the section Experimental Set-Up and Test Matrix).Dimensions are in millimeters.

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Evaluation of Biofidelity of New JARI LegformImpactor

Experimental Set-Up and Test Matrix The newlegform impactor was evaluated against the responsesof PMHS legs determined by Wittek et al. (2000) usingthe results of the experiments conducted by Kajzer etal. (1997, 1999). In these experiments, the PMHS legswere impacted in a lateral direction at two speeds: 1)5.56 m/s (20 km/h) and 2) 11.11 m/s (40 km/h). Twoimpact configurations were used: 1) shearing (impactpoint at the fibula head level) (Figure 3), and 2)bending (impact in the ankle area) (Figure 4).

In the present study, we conducted eight impacttests of the new JARI impactor under conditionsclosely replicating the set-up of the experiments byKajzer et al. (1997, 1999) (Figures 3 and 4, Table 1).Duplicating their experimental procedure, we struckthe impactor leg with a metal ram padded with onelayer of StyrodureTM foam of the same dimensions asthose used in the PMHS experiments by Kajzer et al.(1997, 1999). The mass of our ram differed by only0.02 kg from theirs.

To reproduce the 400 N pre-load applied to thePMHS by Kazjer et al. (1997, 1999), we pre-loaded theimpactor with a 41.6 kg mass attached to the impactortop by means of a spherical joint (Figures 3 and 4). To

simulate the constraints applied to the PMHS thighs,we supported the impactor thigh with two bolts of thesame diameter as that used by Kajzer et al. (1997,1999). To represent the ground, we used thick steel andteflon plates in the shearing and bending tests,respectively. The teflon plate was applied to minimizethe effects of friction between the impactor leg and theground in the bending tests.

As already mentioned, the leg of the new JARIimpactor consists of a very stiff cylindrical shaft. Thecontact stiffness between such a shaft and the foampadding of the side ram is likely to be higher than thatof the contact between the padding and a human leg.Therefore, in all our tests, a 25 mm layer of memoryfoam (ConforTM foam by Ear Specialty CompositesCorp., USA) was attached to the impactor leg torepresent a human leg flesh. The use of this foam isrecommended in a working draft of the EuropeanRegulations (EEVC, 1998).

In the experiments by Kajzer et al. (1997, 1999), theposition of the impact point varied because ofdifferences in the size of the PMHS bodies. Therefore,when evaluating the new JARI impactor, we used theaverage position of the impact point determined inthese experiments: 84 mm and 377 mm below the kneejoint center in the shearing and bending tests,respectively.

a) b)

Figure 3. a) Set-up of the shearing-type PMHS experiments by Kajzer et al. (1997, 1999). Based on Kajzer etal. (1997). b) Set-up of the shearing-type biofidelity tests of the new JARI legform impactor.

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a) b)

Figure 4. a) Set-up of the bending-type PMHS experiments by Kajzer et al. (1997, 1999). Based on Kajzer etal. (1997). b) Set-up of the bending-type biofidelity tests of the new JARI legform impactor.

Table 1.Test matrix for evaluating biofidelity of the new

JARI impactor

ExperimentNumber

Type of Impact Impact Speedm/s (km/h)

BJJ02, BJJ03 Shearing 5.56 (20.0)BJJ04, BJJ05 Shearing 11.11 (40.0)BJJ06, BJJ07 Bending 5.56 (20.0)BJJ08, BJJ09 Bending 11.11 (40.0)

Analyzed Variables In evaluation of thebiofidelity of the present impactor, we compared itsimpact force, leg shearing displacement and legbending angle with the corridors (average -/+ standarddeviation SD) of the responses of the human lowerextremity determined by Wittek et al. (2000) using theresults of PMHS experiments by Kajzer et al. (1997,1999). Following Kajzer et al. (1997, 1999), wecalculated the impact force (i.e., the force between theimpactor leg and the impacting side ram) as the productof the ram mass and acceleration. The leg shearingdisplacement D was determined by means of thefollowing formula:

D X X gP P= − −4 3 sin( )α , (1)

where g is the position of marker P4 in relation to thecenter of the knee joint measured along thelongitudinal leg axis, and α is the bending angle of aleg. XP3 and XP4 are coordinates of markers P3 and P4in a lateral direction, respectively (Figure 5). The legbending angle α was obtained as follows:

α = −−

arctanX XZ Z

P P

P P

2 1

1 2, (2)

where XP1 and XP2 are coordinates of markers P1 andP2 in a lateral direction, and Z P1 and ZP2 arecoordinates of markers P1 and P2 in a verticaldirection.

Coordinates of all the markers were determinedfrom high-speed video tape digitized and analyzed bymeans of the NAC Image-Express workstation (NAC,1995). The tape recording speed was 500 frames persecond. This implies that when calculating the legbending angle and leg shearing displacement, we wereable to determine the start of impact (i.e., zero on thetime axis) with an accuracy not greater than 2 ms.

Figure 5. Scheme of calculation of leg shearingdisplacement D and bending angle α.

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Comparison of Biofidelity of TRL and New JARIImpactors

The responses of the TRL impactor used here werefrom Matsui et al. (1999) who conducted theirexperiments without a damper attached to the impactorshear system. These responses could be compared withthe behavior of the new JARI impactor to a limitedextent only because the TRL impactor was notevaluated in shearing-type impacts at a speed of 11.11m/s to minimize the risk of damage.

RESULTS

Impact Force

In shearing-type tests at an impact speed of 11.11m/s and for bending-type tests at both impact speeds of5.56 m/s and 11.11 m/s, the peak values of the impactforce-time histories of the new JARI impactor werewithin the response corridors determined using theresults of the PMHS experiments by Kajzer et al.(1997, 1999) (Figures 6 and 7). However, in shearing-type tests at an impact speed of 5.56 m/s, the peakimpact forces of both these impactors were higher thanthose measured on PMHS (Figure 6a). Thisphenomenon may be related to the following twofactors. The first is that the eminence of the meniscusof the new JARI impactor is thicker and broader thanthat of the human knee joint, which may result in toohigh stiffness of the knee joint in this impactor. Thesecond factor that could lead to relatively high impactforce of the new JARI impactor in shearing-type testsat low impact speed is that the leg of this impactorconsists of a virtually rigid tube that directly interactswith the simulated ground, which cannot representeffects of inversion/eversion in the ankle joint on theresponses of human lower extremity.

Furthermore, peaks of the impact force-timehistories of both the TRL and new JARI legformimpactors were delayed in relation to those of thePMHS legs (Figure 6 and 7). This delay was clearlyshorter at an impact speed of 11.11 m/s than 5.56 m/s,and similar for both impactors. Therefore, we suggestthat the present delay in the peak impact force of theTRL and new JARI impactors could be caused by thelow stiffness of the memory foam used as leg paddingin these impactors, which could result in a low rate ofincrease in the impact force. However, the presentstudy alone is not sufficient to verify the validity of thissuggestion.

A comparison of the responses between the TRLand new JARI impactors indicated only minordifferences between their impact force-time histories(Figures 6 and 7).

0

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New JARITRLPMHS (Aver. -/+ SD)

Impa

ct F

orce

(S

hear

. 5.

56 m

/s)

[N]

Time [ms]

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New JARIPMHS (Aver. -/+ SD)

Impa

ct F

orce

[N

] (S

hear

. 1

1.11

ms/

) Time [ms]

Figure 6. Comparison of impact force-timehistories of the TRL and new JARI impactors withPMHS responses. Shearing-type tests. Impactspeeds of a) 5.56 m/s and b) 11.11 m/s.a)

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[N

] (B

end.

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/s)

Time [ms] Figure 7. Comparison of impact force-timehistories of the TRL and new JARI impactors withPMHS responses. Bending-type tests. Impact speedsof a) 5.56 m/s and b) 11.11 m/s.

a)

b)

b)

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Leg Shearing Displacement

In the initial phase of the impact at a speed of 5.56 m/s,the shearing displacement-time histories of the newJARI impactor were within the response corridorsdetermined on PMHS. However, the rate of theirincrease was lower than that observed on PMHS. Inconsequence, at an impact speed of 5.56 m/s, the peakvalue of the shearing displacement of the new JARIimpactor leg was around 14 mm, which is clearlybelow the lower limit of the PMHS responses (Figure8a). One possible explanation for this phenomenon canbe the high stiffness of the knee joint of this impactor

at low impact speed as discussed on page 5. On theother hand, at a speed of 11.11 m/s, the shearingdisplacement-time histories of the new JARI impactorwere very close to the lower limit of the PMHSresponses (Figure 8b).

In contrast to the new JARI impactor, the shearingdisplacement-time histories of the TRL one exhibited alimit of 7.5 mm. Therefore, the shearing displacement-time histories of the new JARI impactor compared tothe TRL one were appreciably closer to the PMHSresponses (Figure 8).

a) b)

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New JARITRLPMHS (Aver. -/+ SD)

She

ar D

isp.

(S

hear

. 5.

56 m

/s)

[mm

]

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New JARIPMHS (Aver. -/+ SD)

She

ar D

isp.

(S

hear

11.

11 m

/s)

[mm

]

Time[ms]

Figure 8. Comparison of shearing displacement-time histories of the TRL and new JARI impactors withPMHS responses. Shearing-type tests. Impact speeds of a) 5.56 m/s and b) 11.11 m/s.

Leg Bending Angle

Shearing-Type Tests In these tests, the bendingangle-time histories of the new JARI impactor werevery close to the upper limit of the PMHS responses atboth impact speeds of 5.56 and 11.11 m/s (Figure 10).However, in case of the PMHS, these time historiesexhibited negative values of up to -10° in the initialimpact phase, i.e., displacement of the leg proximalpart in a lateral direction was greater than that of thedistant part, whereas the new JARI impactor yielded aminimum value of the bending angle of only around-2°. One possible explanation for the differences in thebending angle-time histories between the new JARIlegform impactor and the human lower extremity maybe the following. The impactor leg is virtually rigid,and negative values in its bending angle-time historiesresult from its rigid-body motion alone (Figure 9b). Onthe other hand, an appreciable bending-typedeformation of the PMHS legs was observed in theexperiments by Kajzer et al. (1997, 1999). Thus, intheir experiments, negative bending angle could resultnot only from motion of the leg as a rigid-body, but

also from the deformation of tibia and fibula (Figure9a).

a) b)

Figure 9. Negative bending angle of a) Human leg(α1); b) Legform impactor with a rigid leg (α2).

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a) b)

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5.56

m/s

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eg]

Time[ms]

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New JARIPMHS (Aver. -/+ SD)

Ben

ding

Ang

le (

11.1

1 m

/s)

[deg

]

Time[ms]

Figure 10. Comparison of bending angle-time histories of the new JARI impactor with responses of PMHS.Shearing-type tests. Impact speeds of a) 5.56 m/s and b) 11.11 m/s.

Bending-Type Tests In these tests, the bendingangle-time histories of the new JARI legform impactorwere within the PMHS response corridors during theinitial 20 and 25 ms of impacts at speeds of 11.11 m/sand 5.56 m/s, respectively. For time values exceedingthese initial time-windows, the bending angle-timehistories of this impactor were slightly above the upperlimits of the PMHS responses (Figure 11).

On the other hand, magnitudes of the bendingangle-time histories of the TRL impactor at a speed of5.56 m/s were lower than those obtained in the PMHSexperiments. For a speed of 11.11 m/s, the peakbending angle of the TRL impactor was above thelower limit of the PMHS responses (Figure 11).

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Ben

ding

Ang

le (

11.1

1 m

/s)

[deg

]

Time[ms]

Figure 11. Comparison of bending angle-time histories of the TRL and new JARI impactor with responses ofPMHS. Bending-type tests. Impact speeds of a) 5.56 m/s and b) 11.11 m/s.

DISCUSSION

Evaluation of Biofidelity of New JARI LegformImpactor

Responses of the new legform impactor developed inthe present study were reasonably close to those of thehuman lower extremity determined by Wittek et al.(2000) using the results of PMHS experiments byKajzer et al. (1997, 1999). The peak values of theimpact force-time histories of this impactor werewithin the corridors of the PMHS responses for all the

analyzed tests, except for the shearing-typeexperiments at a speed of 5.56 m/s (Figures 6 and 7). Inthese experiments, the peak impact force of the newJARI impactor was around 25% higher than thatmeasured on PMHS (Figure 6a), which might berelated to the oversized tibial eminence anddisregarding the ankle joint in this impactor.

Furthermore, the peaks of the impact force-timehistories of the new JARI impactor were delayed inrelation to those determined using PMHS. We suggestthat this delay might be caused by the low stiffness ofthe memory foam we used as padding for the impactor

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leg. However, the present study is insufficient toconfirm this suggestion. Therefore, we cannot excludethe possibility that the present discrepancies betweenthe impact force-time histories obtained using PMHSand the new JARI legform impactor were also relatedto factors other than the properties of the leg paddingfoam. One of such factors could be the characteristicsof the contact between the PMHS`s foot and simulatedground in the experiments by Kajzer et al. (1997,1999), which differed from those of the contactbetween the distal end of our impactor leg and thesteel/teflon plates used to represent the ground in thepresent study.

As with the impact force, the peak values of theshearing displacement of the new JARI impactor werewithin the corridor of the PMHS responses at an impactspeed of 11.11 m/s (Figure 8b). However, at 5.56 m/s,they were below the lower limit of these responses(Figure 8a). One possible reason for the too lowshearing displacement of the new JARI impactor in theshearing tests at 5.56 m/s may be differences betweenthe size of the tibial meniscus in this impactor and inthe human knee joint as already mentioned in theDISCUSSION.

In the bending-type impacts, the bending angle-timehistories of the new JARI impactor were within thePMHS response corridors during the initial 20 and 25ms of impacts at speeds of 11.11 and 5.56 m/s,respectively (Figure 11). In the impact phase followingthese initial time-windows, the magnitudes of thesetime histories were slightly above the upper limits ofthe PMHS responses. This discrepancy between thebending angle-time histories of the new JARI impactorand the human leg seems to be too small tocompromise the biofidelity of this impactor. However,it may be of importance when applying the new JARIimpactor as a test device since, even at an impact speedof 5.56 m/s (20 km/h), the peak values of its bendingangle-time histories exceeded a limit of 15° proposedin the EEVC (1998) report as the acceptance level forlegform impactor to bumper test.

In shearing-type impacts, the bending angle-timehistories of the new JARI impactor were also veryclose to the upper limit of the PMHS responses (Figure10). However, in the initial phase of shearing-typeimpacts, considerably negative values of the bendingangle were observed in the motion of the PMHS`s legs,whereas for the new JARI impactor, the minimumbending angle was only around -2°. The likely reasonfor this phenomenon is that the leg of this impactor isvirtually rigid, whereas a notable bending-typedeformation of the human leg was observed in thePMHS experiments by Kajzer et al. (1997, 1999). Ourreason for disregarding the leg deformation was thatthe application of a rigid leg is simple and commonly

accepted in design of legform impactors, e.g., the TRLimpactor (EEVC, 1998).

Comparison of Biofidelity of TRL and New JARILegform Impactors

Despite only minor differences in the impact force-timehistories of the TRL and new JARI impactors, theirkinematics differed significantly. Magnitudes of theshearing displacement and bending angle-time historiesof the new JARI impactor were appreciably higher andcloser to the PMHS responses than those of the TRLimpactor. Thus, it can be concluded that the design ofthe complex structure simulating the geometry andmechanical properties of the human knee joint in thenew JARI impactor made it possible to achievebiofidelity exceeding that of the other legformimpactors reported in the literature.

Recommendations for Further Studies

The present investigation indicated that, although thepeak values of the impact force-time histories of theTRL and new JARI legform impactors are close tothose determined in the experiments on PMHS, theyare delayed in comparison to the PMHS histories. Thisdelay is very similar for both these impactors despitedifferences in the structure and geometry of their kneejoints. This, in turn, suggests that the delay is notrelated to the features of their knee joints as such, butrather to the properties of contact between the side ramand legs of these impactors. As discussed earlier (seepage 5), these properties can be determined by the lowstiffness of the memory foam (ConforTM) utilized as legpadding in both the TRL and new JARI impactors. Wedid not attempt to determine to what extent theproperties of this foam are similar to those of humanflesh since its application was recommended in theproposed European standard (EEVC, 1998). However,our experience in conducting experiments using theConforTM foam suggests that its stiffness is verysensitive to temperature and may exhibit some strain-rate dependency. Therefore, we recommend that aparametric study be done to determine if an increase inthe static stiffness of leg padding reduces the delay inthe impact force-time histories of the new JARI andTRL legform impactors.

As already suggested in the R E S U L T S andDISCUSSION, one possible reason for the differencesin the bending angle-time histories between the newJARI impactor and the PMHS lower extremities undera shearing-type load may be the use of a virtually rigidtube to represent a leg in this impactor. A direct way toconfirm validity of this suggestion is to add adeformable leg to the new JARI impactor.

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Furthermore, in bending-type impacts, the legbending angle-time histories of the new JARI impactorwere slightly above the upper limits of the PMHSresponses for time values exceeding 20 and 25 ms atimpact speeds of 11.11 and 5.56 m/s, respectively. Onepossible solution to reduce the magnitude of these timehistories can be to increase the stiffness of springs ofthe knee joint ligaments.

Our recommendations for further studies are basedon hypotheses regarding the causes of the presentdifferences between the responses of the new JARIlegform impactor and a human lower extremity.However, the present study was designed to evaluatethe general biofidelity of this impactor, and it does notenable us to thoroughly confirm these hypotheses. Thevalidation of our suggestions for improvement ofbiofidelity of the new JARI legform impactor requiresa new experimental investigation.

CONCLUSIONS

In the present study we developed a new legformimpactor (referred to as the new JARI impactor) andevaluated its biofidelity. The responses of this impactorwere close to those of the human leg. In bending-typeimpacts at speeds of 5.56 and 11.11 m/s and inshearing-type impacts at a speed of 11.11 m/s, the peakvalues of its shearing displacement and its bendingangle-time histories were nearly within the corridorsdetermined in the experiments using PMHS. Theseresults imply that the new JARI legform impactorrather than the TRL impactor more accuratelyrepresents the kinematics of the human leg in lateralimpacts.

It is important to determine the cause and reduce thedifferences between the responses of the new JARIimpactor and human lower extremities. One suchdifference is delay in the peak of the impact force ofthis impactor and too low magnitude of negative valuesin its bending angle-time histories in the initial phase ofshearing-type impacts. To achieve this we suggest thefollowing: 1) To conduct lateral impact experimentsusing an impactor leg padding with a higher staticstiffness than the currently used ConforTM foam; and 2)To replace the rigid impactor leg with a deformableone.

ACKNOWLEDGEMENTS

The present study is part of a research projectsponsored by the Pedestrian Working Group of JapanAutomobile Manufacturers Association in fiscal 2000.

The new legform impactor was manufactured byGESAC Inc. and jointly developed by the GESAC Inc.,Japan Automobile Research Institute, and HONDAR&D.

REFERENCES

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EEVC (1998), European Enhanced Vehicle-safetyCommittee, Improved Test Methods to EvaluatePedestrian Protection Afforded by Passenger Cars,EEVC Working Group 17 Draft Report, 1998.

ITARDA (1996), Institute for Traffic AccidentResearch and Data Analysis of Japan, AnnualTraffic Accident Report in 1995 (in Japanese),Tokyo.

ISO (1996), International Standard Organization,Passenger Cars and Light Commercial Vehicles-Pedestrian Protection-Impact Test Method forPedes t r ian Lower Leg and Knee,ISO/TC22/SC10/WG2 Working Draft 11.

Kajzer, J., Schroeder, G., Ishikawa, H., Matsui, Y., andBosch, U. (1997), Shearing and bending effects atknee joint at high speed lateral loading, Proc. of theInt. IRCOBI Conference on the Biomechanics ofImpacts, Hannover, Germany, pp. 151-165.

Kajzer, J., Matsui, Y., Ishikawa, H., Schroeder, G., andBosch, U. (1999), Shearing and bending effects atthe knee joint at low speed lateral loading, Proc. ofthe SAE International Congress, Society ofAutomotive Engineers, Detroit, Michigan, USA, pp.1-12.

Matsui, Y., Ishikawa, H., Sasaki, A., Kajzer, J., andSchroeder, G. (1999), Impact response andbiofidelity of pedestrian legform impactors, Proc. ofthe Int. IRCOBI Conference on the Biomechanics ofImpacts, Barcelona, Spain, pp. 343-354.

NAC (1995), Image Express Users Manual ForApplication Version 1.26, NAC Incorporated,Woodland Hills, California, USA.

Wittek, A., Ishikawa, H., Matsui, Y., and Konosu., A(2000), Validation and parameter study of a multi-body model for simulation of knee joint responsesin lateral impacts representing car-pedestrianaccidents: Influences of ligament properties andboundary conditions on model responses, Proc. ofthe Int. IRCOBI Conference on the Biomechanics ofImpacts, Montpellier, France, pp. 85-100.