NHTSA Evaluation of the Flex-GTR Legform on US Vehicles Brian Suntay & Ann Mallory Transportation Research Center Inc. Jason Stammen NHTSA Vehicle Research and Test Center 1 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.
Pedestrian Leg Testing The Pedestrian Global Technical Regulation (GTR No. 9) includes a projectile leg simulating a moving vehicle hitting a stationary pedestrian at 40 km/h 2
Goals of the Testing 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 3
Pedestrian Legforms TRL Flex-GTR 4
TRL Rigid Legform Impactor Steel femur and tibia segments Frangible steel ligaments Instrumentation: Tibia accelerometer Rotary pot with rigid arm 5
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) 6
Injury Assessment Bending Injury Measures Knee Bending Angle MCL Elongation Shear Injury Measures Knee Shear Displacement ACL/PCL Elongation TRL Tibia Fracture Measures Tibia Acceleration Tibia Bending Moment 7 Flex-GTR
Volkswagen Mazda Honda
Honda Chevrolet Chevrolet
Test Results 10
TRL Test Results Peak Shear Displacement (mm) Peak Bending Angle (deg) 8.1 31.1 8.9 26.5 8.9 33 6.8 33 8.3 26.5 7.5 33.1 0 2 4 6 8 10 0 5 10 15 20 25 30 35 Peak Tibia Acceleration (g) 307 402 326 401 353 183 0 100 200 300 400 500 11
Peak Tibia 1 Moment (Nm) Flex-GTR Test Results Peak ACL Elongation (mm) 428 13.9 460 14.3 475 14.8 402 15.5 333 378 7.9 11.9 0 100 200 300 400 500 0 5 10 15 20 Peak MCL Elongation (mm) 28.2 24.1 27.0 32.1 22.3 34.4 0 10 20 30 40 Peak PCL Elongation (mm) 7.9 6.4 7.2 7.1 5.6 8.4 0 2 4 6 8 10
Comparison of Results TRL vs Flex-GTR 13
Comparison of Results TRL vs Flex-GTR Fracture Measures Bending Injury Measures 0 50 100 150 200 Injury Measure as % of Limit 0 50 100 150 200 Injury Measure as % of Limit TRL - Tibia Acceleration Flex-GTR - Max Tibia Bend Moment TRL - Knee Bending Angle Flex-GTR - MCL Elongation Shear Injury Measures 0 50 100 150 200 Injury Measure as % of Limit TRL - Knee Shear Displacement Flex-GTR - Max ACL/PCL Elongation
Comparison of Results TRL vs Flex-GTR Fracture Measures Bending Injury Measures 180 200 FlexGTR % of Injury Limit 160 140 120 100 80 60 40 20 FlexGTR % of Injury Limit 180 160 140 120 100 80 60 40 20 0 0 20 40 60 80 100 120 140 160 180 0 0 20 40 60 80 100120 140 160 180200 TRL % of Injury Limit TRL % of Injury Limit 160 Shear Injury Measures FlexGTR % of Injury Limit 140 120 100 80 60 40 20 0 0 20 40 60 80 100 120 140 160 TRL % of Injury Limit
Summary of Findings 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, 21 st 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, 22 nd International Technical Conference on the Enhanced Safety of Vehicles, 2011. Aggressive vehicle bumper impact locations chosen 16
Flex-GTR Vehicle Sensitivity 17
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) Fracture Bend Shear Results from current series of tests Fracture Measures Bending Injury Measures Shear Injury Measures 0 50 100 150 200 Injury Measure as % of Limit 0 50 100 150 200 Injury Measure as % of Limit 0 50 100 150 200 Injury Measure as % of Limit Three additional tests performed on the center of the three passenger cars
Volkswagen Mazda Honda
Comparison of Old and New Flex-GTR Data Center Impacts Fracture Measures Bending Injury Measures 0 20 40 60 80 100 120 140 Flex-GTR (New) - Max Tibia Bend Moment Flex-GTR (Old) - Max Tibia Bend Moment 0 20 40 60 80 100 120 140 Flex-GTR (New) - MCL Elongation Flex-GTR (Old) - MCL Elongation Shear Injury Measures 0 20 40 60 80 100 120 Flex-GTR (New) - Max ACL/PCL Elongation Flex-GTR (Old) - Max ACL/PCL Elongation
Summary of Findings 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 21
Flex-GTR Durability 22
Observations and Durability Assessment (Flex-GTR) Misalignment of the knee after impacts Femur strain gauge #2 (middle gauge) Broken gauge/wire Still being investigated Tear in the neoprene skin and scratches on the femur knee block
Summary of Findings 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 24
Flex-GTR Repeatability (Additional Observation) 25
Flex-GTR Repeatability Impact Location Injury Measurement Injury Reference Value (FlexTEG) Chevrolet Center GTR (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 1 (Upper) 332.7 332.6 0% Tibia Moment (Nm) Tibia 2 (Mid Upper) Tibia 3 (Mid Lower) 340 Nm (380 Nm) 311.1 319.5 3% 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% 26
Summary of Findings 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 Flex-GTR repeatability was not directly evaluated, but Flex-GTR tests 1001 and 1002 showed similar values at the same impact location, which is promising 27
NHTSA Evaluation of the Flex-GTR Legform on US Vehicles Brian Suntay & Ann Mallory Transportation Research Center Inc. Jason Stammen NHTSA Vehicle Research and Test Center 28 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.