nhtsa evaluation of the flex-gtr legform on us … meetings/sae...brian suntay & ann mallory...
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NHTSA Evaluation of the Flex-GTR Legform on US
VehiclesBrian Suntay & Ann Mallory
Transportation Research Center Inc.
Jason StammenNHTSA Vehicle Research and Test Center
This is a work of the U.S. Government and is not subject to copyright in the United States; it may be used or reprinted without permission.
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The Pedestrian Global Technical Regulation (GTR No. 9) includes a projectile leg simulating a moving vehicle hitting a stationary pedestrian at 40 km/h
Pedestrian Leg Testing
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Comparison of vehicle performance with TRL versus Flex-GTR legforms
Confirm whether the Flex-GTR legform is sensitive enough to distinguish marginally performing vehicles from poor performing vehicles
Test the Flex-GTR’s durability against aggressive locations on US vehicle bumpers
Goals of the Testing
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TRL
Pedestrian Legforms
Flex-GTR
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TRL Rigid Legform Impactor
Steel femur and tibia segments◦ Frangible steel ligaments
Instrumentation:◦ Tibia accelerometer◦ Rotary pot with rigid arm
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Flex-GTR Flexible Legform Impactor◦ Increased biofidelity
Flexible bone core, wire ligaments, knee tension cables
Instrumentation:◦ Tibia and Femur strain
gauges◦ Ligament string
potentiometers (MCL, ACL, PCL, ACL)
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Injury AssessmentBending Injury Measures
Knee Bending AngleMCL Elongation
Shear Injury MeasuresKnee Shear Displacement
ACL/PCL Elongation
Tibia Fracture MeasuresTibia Acceleration
Tibia Bending MomentTRL Flex-GTR
Volkswagen Passat
Mazda Miata
Honda Civic
Honda Pilot
Chevrolet Silverado
Chevrolet Equinox
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Test Results
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33.1
26.5
33
33
26.5
31.1
0 5 10 15 20 25 30 35
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Bending Angle (deg)
TRL Test Results
7.5
8.3
6.8
8.9
8.9
8.1
0 2 4 6 8 10
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Shear Displacement (mm)
183
353
401
326
402
307
0 100 200 300 400 500
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Tibia Acceleration (g)
8.4
5.6
7.1
7.2
6.4
7.9
0 2 4 6 8 10
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak PCL Elongation (mm)
34.4
22.3
32.1
27.0
24.1
28.2
0 10 20 30 40
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak MCL Elongation (mm)
378
333
402
475
460
428
0 100 200 300 400 500
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Tibia 1 Moment (Nm)Flex-GTR Test Results
11.97.9
15.5
14.8
14.3
13.9
0 5 10 15 20
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak ACL Elongation (mm)
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Comparison of ResultsTRL vs Flex-GTR
Comparison of Results – TRL vs Flex-GTR
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Fracture Measures
TRL - Tibia Acceleration Flex-GTR - Max Tibia Bend Moment
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Bending Injury Measures
TRL - Knee Bending Angle Flex-GTR - MCL Elongation
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Shear Injury Measures
TRL - Knee Shear Displacement
Flex-GTR - Max ACL/PCL Elongation
Equinox
Silverado
Miata
PilotPassat
Civic
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120 140 160
Fle
xGT
R %
of I
nju
ry L
imit
TRL % of Injury Limit
Shear Injury Measures
PilotPassat
Equinox
Silverado
CivicMiata
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100120 140 160180200
Fle
xGT
R %
of I
nju
ry L
imit
TRL % of Injury Limit
Bending Injury Measures
Equinox
Silverado
Pilot
CivicMiata
Passat
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100 120 140 160 180
Fle
xGT
R %
of I
nju
ry L
imit
TRL % of Injury Limit
Fracture Measures
Comparison of Results – TRL vs Flex-GTR
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The Flex-GTR measures lower values than the TRL legform with respect to their current injury limits◦ Matsui et al., Characteristics of the TRL Pedestrian Legform and the Flexible
Pedestrian Legform Impactors in Car-front Impact Tests, Paper Number 09-0206, 21st International Technical Conference on the Enhanced Safety of Vehicles, 2009.
◦ Yoon et al., Evaluation of Usefulness and Repeatability for Pedestrian Protection Flex-PLI, Paper Number 11-0425, 22nd International Technical Conference on the Enhanced Safety of Vehicles, 2011.
Aggressive vehicle bumper impact locations chosen
Summary of Findings
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Flex-GTR Vehicle Sensitivity
Testing with a previous version of the Flex-GTR legform suggested an inability of the legform to distinguish among vehicles that performed poorly (Mallory, 2010)
Results from current series of tests
Three additional tests performed on the center of the three passenger cars
Sensitivity
Fracture Bend Shear
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Fracture Measures
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Bending Injury Measures
0 50 100 150 200
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Shear Injury Measures
Volkswagen Passat
Mazda Miata
Honda Civic
Comparison of Old and New Flex-GTR Data – Center Impacts
0 20 40 60 80 100 120 140
Civic
Miata
Passat
Fracture Measures
Flex-GTR (New) - Max Tibia Bend Moment
Flex-GTR (Old) - Max Tibia Bend Moment
0 20 40 60 80 100 120 140
Civic
Miata
Passat
Bending Injury Measures
Flex-GTR (New) - MCL Elongation
Flex-GTR (Old) - MCL Elongation
0 20 40 60 80 100 120
Civic
Miata
Passat
Shear Injury Measures
Flex-GTR (New) - Max ACL/PCL Elongation
Flex-GTR (Old) - Max ACL/PCL Elongation
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The Flex-GTR measures lower values than the TRL legform with respect to their current injury limits
The Flex-GTR seems to be able to distinguish differences in relatively aggressive vehicle bumper designs
Summary of Findings
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Flex-GTR Durability
Observations and Durability Assessment (Flex-GTR)
Misalignment of the knee after impacts
Tear in the neoprene skin and scratches on the femur knee block
Femur strain gauge #2 (middle gauge)◦ Broken gauge/wire◦ Still being investigated
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The Flex-GTR measures lower values than the TRL legform with respect to their current injury limits
The Flex-GTR seems to be able to distinguish differences in relatively aggressive vehicle bumper designs
The Flex-GTR was observed to be durable◦ Survived US vehicle bumper impacts that exceeded injury
limits◦ A majority of the issues that were observed were minor and
repairable
Summary of Findings
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Flex-GTR Repeatability(Additional Observation)
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Flex-GTR RepeatabilityInjury Measurement
Injury Reference
Value (FlexTEG)
Chevrolet Silverado
Impact Location CenterGTR (1001) GTR (1002) %Difference
Femur Moment (Nm)
Femur 3 (Upper)--*
73.7 77.3 5%
Femur 2 (Middle) 139.5 138.5 1%
Femur 1 (Lower) 252.1 245.6 3%
Tibia Moment (Nm)
Tibia 1 (Upper)
340 Nm (380 Nm)
332.7 332.6 0%
Tibia 2 (Mid Upper)311.1 319.5 3%
Tibia 3 (Mid Lower)233.5 237.4 2%
Tibia 4 (Lower) 110.5 107.9 2%
MCL Elongation (mm) 22 mm -- 22.3 NA
ACL Elongation (mm) 13 mm 8 7.9 1%
PCL Elongation (mm) 13 mm 5.4 5.6 4%
LCL Elongation (mm) --* -4.2 -3.8 10%
Tibia Acceleration (g) --* -59.2 -59.5 1%Velocity (m/s) --* 11.1 11.1 0%
Average: 3%
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The Flex-GTR measures lower values than the TRL legformwith respect to their current injury limits
The Flex-GTR seems to be able to distinguish differences in relatively aggressive vehicle bumper designs
The Flex-GTR was observed to be durable◦ Survived US vehicle bumper impacts that exceeded injury limits◦ A majority of the issues that were observed were minor and
repairable
Flex-GTR repeatability was not directly evaluated, but◦ Silverado Flex-GTR tests 1001 and 1002 showed similar values at
the same impact location, which is promising
Summary of Findings
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NHTSA Evaluation of the Flex-GTR Legform on US
VehiclesBrian Suntay & Ann Mallory
Transportation Research Center Inc.
Jason StammenNHTSA Vehicle Research and Test Center
This is a work of the U.S. Government and is not subject to copyright in the United States; it may be used or reprinted without permission.
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