flexpli vs. eevc lfi correlation - unece
TRANSCRIPT
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FlexPLI vs. EEVC LFI Correlation
5th IG GTR9-PH2 Meeting 6-7/December/2012
Japan Automobile Standards Internationalization Center (JASIC)
Action List Item 1. j) Evaluate and decide on performance / injury criteria and threshold values
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IWG Questions from NHTSA
Reference : National Highway Traffic Safety Administration (NHTSA), Overview of NHTSA Pedestrian Activities, 4th IG GTR9-PH2 Meeting Document, GTR9-4-19 (2012)
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Leg Fracture Evaluation
64 mm
Knee center
Upper Tibia Acceleration
No instrumentation
Injury Criterion
EEVC LFI FlexPLI
374 mm
137 mm
217 mm
297 mm
134 mm
214 mm
294 mm
Upper end of tibia
Femur-3 BM
Femur-2 BM
Femur-1 BM
Tibia-1 BM
Tibia-2 BM
Tibia-3 BM
Tibia-4 BM
BM: Bending Moment
Injury Criteria
� EEVC LFI measures upper tibia acceleration at one location � FlexPLI measures tibia bending moment at four locations
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Leg Fracture Evaluation
Predominant factor for EEVC LFI upper tibia acceleration �� Applied force magnitude
Mizuno et al. (2012) EEVC LFI Upper Tibia Acceleration
TFFxm ��� sb22 ��
2
sb2A m
FFxa ��� ��
Equation of Motion of tibia
2202
20A
6)06.0(
066.0
�
�����
����
����
��
LLx
xa
Tibia acceleration Bumper force Spoiler force
Fb
Fs L0
0.066 m
�2
x0
x2
aA
T
Reference : Mizuno, K. et al., Comparison of Reponses of the Flex-PLI and TRL Legform Impactors in Pedestrian Tests, SAE World Congress, SAE Paper #2012-01-0270 (2012)
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Leg Fracture Evaluation
Predominant factor for FlexPLI tibia bending moment �� Applied force magnitude AND point of force application
Mizuno et al. (2012)
Reference : Mizuno, K. et al., Comparison of Reponses of the Flex-PLI and TRL Legform Impactors in Pedestrian Tests, SAE World Congress, SAE Paper #2012-01-0270 (2012)
FlexPLI Tibia Bending Moment
s0
s0sb0bs
)()()( zL
zLFzLFzM ����
� �b00
ssbbb )( zL
LzFzFzM �
��
)}(),(max{ bsmax zMzMM �
Max. tibia bending moment
Bending moment Bumper and spoiler force
Point of force application
Fb
Fs L0
zb
zs
R1
R2
M
M(zb)
M(zs)
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Leg Fracture Evaluation Mizuno et al. (2012)
Reference : Mizuno, K. et al., Comparison of Reponses of the Flex-PLI and TRL Legform Impactors in Pedestrian Tests, SAE World Congress, SAE Paper #2012-01-0270 (2012)
FE Validation of Predominant Factors for EEVC LFI Upper Tibia Acceleration
Tibia acc. Bumper force Spoiler force
Presumed from Rigid body model
Fb
Fs
0 5 10 15 20 0
50
100
150
200
250
Tibi
a ac
cele
ratio
n (G
)
Fb+ Fs (kN)
TRL legform FE Model
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Leg Fracture Evaluation Mizuno et al. (2012)
Reference : Mizuno, K. et al., Comparison of Reponses of the Flex-PLI and TRL Legform Impactors in Pedestrian Tests, SAE World Congress, SAE Paper #2012-01-0270 (2012)
FE Validation of Predominant Factors for FlexPLI Tibia Bending Moment
Bend moment Bumper and spoiler force
Point of force application
Presumed from Rigid body model
Fb
Fs
R1
R2 Bending moment
diagram
M(zb)
M(zs)
Flex-PLI FE model
max{M(zs), M(zb)} (kNm)
Tibi
a be
nd m
omen
t (kN
m)
0.0
0.1
0.2
0.3
0.4
0.6 0.8 1.0 1.2
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Leg Fracture Evaluation Takahashi et al. (2012)
Reference : Takahashi, Y. et al., Validation of Pedestrian Lower Limb Injury Assessment using Subsystem Impactors, IRCOBI Conference (2012)
Baseline Model
250 mm
450 mm
650 mm
275 mm
30 mm SP
BP
BLE
SP Location
30 mm -20 mm 0 mm
BP/SP Stiffness
0
5
10
15
0 40 80 120
Forc
e (k
N)
Deflection (mm)
BP
Base Stiff
0
5
10
15
0 40 80 120
Forc
e (k
N)
Deflection (mm)
SP
BaseStiff
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Leg Fracture Evaluation Takahashi et al. (2012)
Reference : Takahashi, Y. et al., Validation of Pedestrian Lower Limb Injury Assessment using Subsystem Impactors, IRCOBI Conference (2012)
EEVC Legform Model
Case StiffnessSteel Material parameters of steelBone Flexural rigidity = 555.6 Nm2
Stiffness of Tibia
CaseStiffness SP
Location (L2 in mm)
CaseStiffness SP
Location(L2 in mm)BP SP Tibia BP SP Tibia
^ Base Base Bone 30 V1-S Base Base Steel 30
V2-B Stiff Base Bone 30 V2-S Stiff Base Steel 30
V3-B Base Stiff Bone 30 V3-S Base Stiff Steel 30
V4-B Base Stiff Bone 0 V4-S Base Stiff Steel 0
V5-B Base Stiff Bone -20 V5-S Base Stiff Steel -20
Simulation Matrix
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Leg Fracture Evaluation Takahashi et al. (2012)
0.0
0.5
1.0
1.5
2.0
2.5
V1 V2 V30.0
0.5
1.0
1.5
2.0
2.5
V1 V2 V3
Nor
mal
ized
Mea
sure
Nor
mal
ized
Mea
sure
Effect of BP/SP Stiffness Tibia Bending Moment
@ BP Height Tibia Acceleration
@ BP Height
Baseline Stiff BP Stiff SP Baseline Stiff BP Stiff SP
Bone Steel
0.0
0.5
1.0
1.5
2.0
2.5
V3 V4 V50.0
0.5
1.0
1.5
2.0
2.5
V3 V4 V5
Nor
mal
ized
Mea
sure
Nor
mal
ized
Mea
sure
Effect of SP Location Tibia Bending Moment
@ BP Height Tibia Acceleration
@ BP Height
SP Forward SP Forward
Bone Steel
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Leg Fracture Evaluation
y = 0.0482x + 1310R = 0.014
0
300
600
900
1200
1500
1800
0 100 200 300 400 500
TRL Legform Flex-PLI
Human Model Tibia Bending Moment (Nm)
TRL
Legf
orm
Mod
el
Upp
er T
ibia
Acc
el. (
m/s
2 )
Human Model Tibia Bending Moment (Nm)
Flex
-PLI
Mod
el
Tibi
a Be
ndin
g M
omen
t (N
m)
y = 1.259x - 72.798R = 0.90
0
100
200
300
400
500
0 100 200 300 400 500
�No correlation between TRL legform upper tibia acceleration and human tibia bending moment
�Good correlation between Flex-PLI and human tibia bending moment
CAE Correlation Study Correlation of Tibia Injury Measures TEG-096
(Flex-PLI)
Konosu et al. (2009)
GTR9-1-05r1
Reference : Japan Automobile Standards Internationalization Center (JASIC), Technical Discussion - Biofidelity, 1st IG GTR9-PH2 Meeting Document, GTR9-1-05r1 (2011)
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Leg Fracture Evaluation � EEVC LFI upper tibia acceleration is solely determined by the
magnitude of applied forces
� FlexPLI tibia bending moment depends on both the magnitude of applied forces and loading locations
� Excessive stiffness of the tibia of EEVC LFI results in much higher sensitivity to the change in the applied force magnitude compared to human bone stiffness
� EEVC LFI upper tibia acceleration shows no correlation with human tibia bending moment due to the use of acceleration as a measure and an excessive stiffness of the tibia
� Direct correlation of EEVC LFI upper tibia acceleration and FlexPLI tibia bending moment makes no sense
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Knee Injury Evaluation
� EEVC LFI individually evaluates bending and shear � FlexPLI measures elongation of ligaments sensitive to both
bending and shear
Shear Disp.
Bending Angle
Individual Measurement
EEVC LFI FlexPLI Injury Criteria
Knee-PCL EL
Knee-MCL EL
Knee-ACL EL
Femur-3 BM
Femur-2 BM
Femur-1 BM
Tibia-1 BM
Tibia-2 BM
Tibia-3 BM
Tibia-4 BM
EL: Elongation Combination
Shearing force Bending force +
MCL LCL
ACL PCL
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Knee Injury Evaluation
� ACL/PCL elongations are sensitive to both bending and shear � MCL elongation is not sensitive to shear due to its length and
distance from center of knee rotation in valgus bending
PCL
ACL
Lateral Impact
MCL LCL
Shear
Valgus Bending
(Posterior View)
MCL: Medial Collateral Ligament ACL: Anterior Cruciate Ligament PCL: Posterior Cruciate Ligament LCL: Lateral Collateral Ligament
PCL
MCL ACL
LCL
(Anterior-oblique view)
Otte et al. (2005)
Knee Anatomy
Center of Rotation
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Human Model MCL Elongation (mm) Fl
ex-P
LI M
odel
M
CL E
long
atio
n (m
m)
TRL Legform Flex-PLI
Human Model MCL Elongation (mm)
TRL
Legf
orm
Mod
el
Knee
Ben
ding
Ang
le (d
eg) y = 0.9821x - 1.0628
R = 0.75
0
10
20
30
40
0 10 20 30 40
y = 0.5584x + 10.335R = 0.55
0
10
20
30
40
0 10 20 30 40
Both TRL legform knee bending angle and Flex-PLI MCL elongation show good correlation with human MCL elongation
TEG-096 (Flex-PLI)
GTR9-1-05r1
Correlation of MCL Injury Measures
Reference : Japan Automobile Standards Internationalization Center (JASIC), Technical Discussion - Biofidelity, 1st IG GTR9-PH2 Meeting Document, GTR9-1-05r1 (2011)
Knee Injury Evaluation GTR9-5-13
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Human Model ACL Elongation (mm)
TRL Legform Flex-PLI
Human Model ACL Elongation (mm)
TRL
Legf
orm
Mod
el
Knee
She
ar D
ispla
cem
ent (
mm
)
y = -0.2699x + 3.8541R = 0.13
0
2
4
6
8
10
12
0 2 4 6
y = 1.3654x + 3.1228R = 0.68
0
2
4
6
8
10
12
0 2 4 6
�No correlation between TRL legform knee shear displacement and human ACL elongation
�Good correlation between Flex-PLI and human ACL elongation
Flex
-PLI
Mod
el
ACL
Elon
gatio
n (m
m)
GTR9-1-05r1
Correlation of ACL Injury Measures
Reference : Japan Automobile Standards Internationalization Center (JASIC), Technical Discussion - Biofidelity, 1st IG GTR9-PH2 Meeting Document, GTR9-1-05r1 (2011)
Knee Injury Evaluation GTR9-5-13
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Knee Injury Evaluation � EEVC LFI individually evaluates knee bending and shear
� FlexPLI directly evaluates elongations of knee ligaments
� Human MCL elongation is insensitive to knee shear due to its length and the distance from the center of knee rotation
� Both EEVC LFI and FlexPLI correlate with human MCL elongation
� EEVC LFI knee shear does not correlate with human ACL elongation due to sensitivity of human ACL elongation to knee bending angle
� Correlation analysis between EEVC LFI knee shear displacement and FlexPLI ACL elongation does not make sense, while correlation analysis between EEVC LFI knee bending angle and FlexPLI MCL elongation is valid
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GTR9-4-18
BASt Study
Reference : BASt, FlexPLI vs. EEVC WG 17 PLI Benefit Estimation, 4th IG GTR9-PH2 Meeting Document, GTR9-4-18 (2012)
Correlation Study - MCL GTR9-5-13
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JAMA Study – Correlation of Knee Bending Measures Correlation Study - MCL
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
18 Simp. ModelCom-ACom-BCom-C (CAE)Com-CCom-ECom-E (CAE)Com-FCom-F (CAE)Com-GCom-HCom-H (CAE)Linear Regression
FlexPLI MCL Elongation (mm)
TRL-
LFI K
nee
Bend
ing
Angl
e (d
eg)
Flex-GTR Test Flex-GTR CAE
R=0.675
Threshold 19 deg
Threshold 22 mm
FlexPLI tends to provide more conservative results than EEVC LFI
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References �National Highway Traffic Safety Administration (NHTSA), Overview of NHTSA Pedestrian
Activities, 4th IG GTR9-PH2 Meeting Document, GTR9-4-19 (2012)
�Mizuno, K. et al., Comparison of Reponses of the Flex-PLI and TRL Legform Impactors in Pedestrian Tests, SAE World Congress, SAE Paper #2012-01-0270 (2012)
�Takahashi, Y. et al., Validation of Pedestrian Lower Limb Injury Assessment using Subsystem Impactors, IRCOBI Conference (2012)
�Japan Automobile Standards Internationalization Center (JASIC), Technical Discussion - Biofidelity, 1st IG GTR9-PH2 Meeting Document, GTR9-1-05r1 (2011)
�BASt, FlexPLI vs. EEVC WG 17 PLI Benefit Estimation, 4th IG GTR9-PH2 Meeting Document, GTR9-4-18 (2012)
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Thank you for your attention
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