Update on Pedestrian Leg TestingComparison of Results –TRL vs Flex-GTR 0 20 40 60 80 100 120 140...
Transcript of Update on Pedestrian Leg TestingComparison of Results –TRL vs Flex-GTR 0 20 40 60 80 100 120 140...
National Highway Traffic Safety Administration
49th GRSP Session May 2011
Nha Nguyen
Update on Pedestrian Leg Testing
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Informal document GRSP-49-23(49th GRSP, 16-20 May 2011,agenda items 4(a))
GTR9-1-12
Pedestrian Leg Testing
Projectile leg simulates a moving vehicle hitting a
stationary pedestrian
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Pedestrian Legforms
TRL
Flex-GT
Flex-GTR3
Background
The Flex-GTR had not been tested against aggressive
vehicles in the US fleet and there was concern about its
durability
There was also concern about topping out the Flex-
GTR’s measurement limits (Mallory, 2010)
Fracture Bend Shear4
Goals of the Testing
This series of impacts was done to test the Flex-GTR against
aggressive US vehicles to see if it would survive
Confirm whether the Flex-GTR legform can distinguish
marginally performing vehicles from poor performing vehicles
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Test Sequence
Due to durability concerns, the TRL legform was tested on each
vehicle first to rank the vehicles in order of increasing
aggressiveness
The Flex-GT was then tested on each vehicle to rank them for
the Flex-GTR tests
This allows us to get in as many tests as possible before possibly
damaging the legform
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Volkswagen Passat
Mazda Miata
Honda Civic
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Honda Pilot
Chevrolet Silverado
Chevrolet Equinox
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Test Results
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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)
TRL Test Results
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)
183
353
401
326
402
307
0 50 100 150 200 250 300 350 400 450
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Tibia Acceleration (g)
*Performed under GTR conditions with legform 25 mm above ground reference level10
9,0
14,4
8,8
10,2
9,4
8,5
0 5 10 15 20
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak PCL Elongation (mm)
12,3
8,4
11,9
14,4
22,8
12,7
0 5 10 15 20 25
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak ACL Elongation (mm)
35,7
23,5
35,5
36,6
31,6
42,5
0 10 20 30 40 50
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak MCL Elongation (mm)
382,6
332,9
417,6
383,1
395,2
329,6
0 100 200 300 400 500
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Tibia 1 Moment (Nm)
Flex-GT Test Results
*Performed under GTR conditions with legform 25 mm above ground reference level
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8,36
5,61
7,05
7,15
6,36
7,91
0 2 4 6 8 10
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak PCL Elongation (mm)
34,37
22,28
32,05
26,99
24,14
28,23
0 10 20 30 40
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak MCL Elongation (mm)
377,5
332,61
402,04
474,6
460,48
428,36
0 100 200 300 400 500
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak Tibia 1 Moment (Nm)
Flex-GTR Test Results
*Performed under GTR conditions with legform 75 mm above ground reference level
11,93
7,87
15,5
14,8
14,3
13,88
0 5 10 15 20
Equinox
Silverado
Pilot
Civic
Miata
Passat
Peak ACL Elongation (mm)
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Comparison of Results
TRL vs GTR
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Comparison of Results –TRL vs Flex-GTR
0 20 40 60 80 100 120 140 160 180
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 20 40 60 80 100 120 140 160
Equinox
Silverado
Pilot
Civic
Miata
Passat
Injury Measure as % of Limit
Shear Injury Measures
TRL - Knee Shear Displacement Flex-GTR - Max ACL/PCL Elongation
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Comparison of Results –TRL vs Flex-GTR
0
20
40
60
80
100
120
140
160
180
0 20 40 60 80 100 120 140 160 180
Fle
x-G
TR
% o
f In
jury
Lim
it
TRL % of Injury Limit
Fracture Measures
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200
Fle
x-G
TR
% o
f In
jury
Lim
it
TRL % of Injury Limit
Bending Injury Measures
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120 140 160
Fle
x-G
TR
% o
f In
jury
Lim
it
TRL % of Injury Limit
Shear Injury Measures
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Summary of Findings
• The Flex-GTR measures lower values than the TRL legform
• The current Flex-GTR seems to be able to distinguish
differences in relatively aggressive vehicle bumper designs
better than the previous version
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Sensitivity
• Testing with a previous version of the Flex-GTR legform showed an inability of the legform to
distinguish among vehicles that performed poorly
•Measurements reached a limit (Mallory, 2010)
• Improvement in the current series of tests may be due to changes in Flex-GTR legform
•Cable stop gap increase
•Femur: 8 mm 9.1 mm
•Tibia: 9 mm 10.3 mm
• Three additional tests performed on the centers of the three passenger cars
Fracture Bend Shear
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Volkswagen Passat
Mazda Miata
Honda Civic
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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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Summary of Findings
The Flex-GTR measures lower values than the TRL legform
The current Flex-GTR seems to be able to distinguish differences in relatively aggressive vehicle bumper designs better than the previous version
Topping out is not a concern with the current Flex-GTR
Flex-GTR repeatability was not directly evaluated, but
Silverado Flex-GTR tests 1001 and 1002 showed similar numbers at the same impact location, which is promising
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Injury Measurement
Injury Reference
Value (FlexTEG)
Chevrolet Silverado
Impact Location Center
GTR (1001) GTR (1002)
Femur Moment
(Nm)
Femur 3 (Upper)
--*
73.67 77.28
Femur 2 (Middle) 139.48 138.52
Femur 1 (Lower) 252.05 245.58
Tibia Moment
(Nm)
Tibia 1 (Upper)
340 Nm (380 Nm)
332.73 332.61
Tibia 2 (Mid Upper) 311.07 319.53
Tibia 3 (Mid Lower) 233.53 237.41
Tibia 4 (Lower) 110.52 107.91
MCL Elongagtion (mm) 22 mm -- 22.28
ACL Elongation (mm) 13 mm 8 7.87
PCL Elongation (mm) 13 mm 5.41 5.61
LCL Elongation (mm) --* -4.16 -3.76
Tibia Acceleration (g) --* -59.21 -59.39
Velocity (m/s) --* 11.055 11.137
Flex-GTR Repeatability – Chevy
Silverado
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Summary of Findings
• The Flex-GTR measures lower values than the TRL legform
• The current Flex-GTR seems to be able to distinguish differences in relatively aggressive vehicle bumper designs better than the previous version• Topping out is not a concern with the current Flex-GTR
• Flex-GTR repeatability was not directly evaluated, but• Silverado Flex-GTR tests 1001 and 1002 showed similar numbers at the
same impact location, which is promising
• The Flex-GTR was observed to be durable• Survived US vehicles• A majority of the issues that were observed were minor and repairable
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Observations and Durability Assessment (Flex-GT)
Pinching of wires between blue tab
and metal knee condyle
Wear and tear of plastic sheath around
knee tension cables
Pushed Surface of the Legform
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Observations and Durability Assessment (Flex-GT)
Tibia and Femur knee blocks are rotated/not flush with each other
Pushed Surface of the Legform
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Observations and Durability Assessment (Flex-GTR)
Misalignment of the knee after Passat and
Miata impacts
Tear in the neoprene skin and scratches
on the femur knee block25
Issues with Flex-GTR
• Needed to modify the legform in order for its flight to be within GTR tolerances for forward pitch (specific to the VRTC launch system)• Removed black protective end caps
• Konosu-san (JARI) informed us that they cut out notches at the top and bottom of the launch plate to accommodate for the end caps
• Femur strain gauge #2 (middle gauge)• Broken gauge/wire• Still being investigated
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Summary of Findings
• Durability:
• The Flex-GTR seems to be able to distinguish differences in
relatively aggressive vehicle bumper designs better than the
previous version
• Flex-GTR repeatability was not directly evaluated, but
• Silverado Flex-GTR tests 1001 and 1002 showed similar numbers at the
same impact location, which is promising
• The Flex-GTR was observed to be durable
• Survived US vehicles
• A majority of the issues that were observed were minor and repairable
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Summary of Findings
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Injury criteria:
The Flex-GTR measures lower values than the TRL legform
Injury results were not consistent with previous testing:
Previous study has shown that it’s rare to injure the ACL or PCL without
injuring MCL. However, in the VW and Honda Civic tests, we observed
ACL elongation that exceeded the injury criteria before the MCL
exceeding injury criterion.
The findings raise concerns on whether the Flex GTR is
properly modeling the impact or that the injury criteria are
appropriate
Conclusion
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Flex-GTR legform is found to be durable
Additional research and testing needed to address the injury
criteria concerns
Currently, more world fleet data is needed
Different evaluation criteria may result in different counter-
measures (design and cost benefit)
Thank you
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