performance of bumper systems with respect to … meetings...results: flexgtr iarv % vs. part 581...
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PERFORMANCE OF BUMPER SYSTEMS WITH RESPECT TO PEDESTRIAN PROTECTION AND BUMPER DAMAGEABILITY REQUIREMENTS
Jason StammenNHTSA
Brian SuntayTransportation Research Center Inc.
2014 SAE Government / Industry Meeting
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.
SAE INTERNATIONAL
• Pedestrian protection standards implemented globally– GTR No. 9 adopted (2008)– FlexGTR legform in process of being added (WP.29 vote May 2014)
• Bumper damageability requirement in U.S. – Part 581 limits damage to vehicle front end in low speed impacts
• Objective: Examine feasibility of passing both GTR9 and Part 581 – Test multiple versions of global platform vehicles with FlexGTR (GTR9)– Test same vehicle configurations in Part 581– Relate test results in 581/GTR9 conditions– Evaluate bumper part design characteristics associated with meeting GTR9
or both GTR9 & Part 581
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BACKGROUND & OBJECTIVES
SAE INTERNATIONAL 3
VEHICLES & CONFIGURATIONS
2013Ford Fusion
2011 Chevrolet Cruze
2006Volkswagen Passat Overseas
Lower Apron
NA Energy Absorber
Overseas Lower Apron
NA Energy Absorber
NA Version
NA Version
NA Version
Overseas Version
Overseas Version NA/O Version
NA/O Version
SAE INTERNATIONAL 4
VEHICLES & CONFIGURATIONS (CONT.)
2012Ford Focus
2010Toyota Yaris
Overseas Lower Apron
NA Bar
NA Version
NA Version
Overseas Version
Overseas Version
NA/O Version
SAE INTERNATIONAL
• GTR9 Test Procedure• FlexGTR legform instead of EEVC legform
METHODS: FLEXGTR TESTING
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MCL & ACL elongations (knee ligament injury risk)
Tibia bending moment (bone fracture injury risk)
SAE INTERNATIONAL
0%
20%
40%
60%
80%
100%
120%
Ford Fusion Chevrolet Cruze VolkswagenPassat
Ford Focus Toyota Yaris Average
Pct o
f AC
L/PC
L El
onga
tion
IAR
V
0%20%40%60%80%
100%120%140%160%
Pct o
f MC
L El
onga
tion
IAR
V
0%20%40%60%80%
100%120%140%
Pct o
f Tib
ia B
endi
ng
Mom
ent I
ARV
RESULTS: FLEXGTR TESTS
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North American
Overseas
North American with Overseas Lower Apron
Part 581 Tested Versions
IARV = 340 N-m
IARV = 22 mm
IARV = 13 mm
SAE INTERNATIONAL
• Fusion passed proposed FlexGTR IARV across bumper width• Outboard edge < center is opposite trend from previous FlexGTR testing
on other NA bumper version vehicles (outboard stiffer due to supports)
RESULTS: FUSION
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Tibia Bending Moment(IARV=340 Nm)
MCL Elongation (IARV=22mm)
ACL Elongation (IARV=13mm)
Pct o
f IAR
V
Center
Outboard Edge
SAE INTERNATIONAL
• Three “global platform” vehicles that passed (or came close to passing) GTR9 with FlexGTR legform
• Fusion (NA), Cruze (NA/O), Passat (NA/O)• Only frontal pendulum portion of series
• B Plane not used (16-20” with mid-plane center matching bumper bar height)• One longitudinal @ 2.5 mph, one corner @ 1.5 mph
• Part 581 criteria• Upper + lower plane < 2000 lbs (8896 N)• No non-bumper components can sustain damage
METHODS: PART 581 TESTING
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SAE INTERNATIONAL
Fusion (NA) Cruze (NA/O) Passat (NA/O)
2.5 mph Longitudinal
Upper + Lower Plane Force (N)[Limit: 8896 N] 704 1861 1576
Mid Plane Force (N) 17783 24485 30048
1.5 mph Corner
Upper + Lower Plane Force (N)[Limit: 8896 N] 1043 1527 770
Mid Plane Force (N) 24791 24452 15675Non-Bumper Damage? No No No
RESULTS: PART 581 TESTS
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SAE INTERNATIONAL
y = 0.0246x + 58.361R² = 0.852
y = -0.0052x + 89.54R² = 0.0471
y = 0.017x + 49.181R² = 0.1712
0
20
40
60
80
100
120
500 1000 1500 2000
% o
f IAR
V
Upper + Lower Plane Force (N)
Tibia Bending Moment
MCL Elongation
ACL Elongation
y = 0.0025x + 32.328R² = 0.9047
y = 0.0011x + 55.546R² = 0.2214
y = 0.0037x - 15.54R² = 0.822
0
20
40
60
80
100
120
15000 20000 25000 30000 35000
% o
f IAR
V
Mid Plane Force (N)
RESULTS: FLEXGTR IARV % vs. PART 581 FORCES
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2.5 MPH Longitudinal Pendulum Test
SAE INTERNATIONAL
• No drastic changes from the N.A. version of the front-end in order to conform to FlexGTR IARV & Part 581• Fusion needed no change• Cruze and Passat needed stiffened lower apron
• Different strategies employed by OEMs to meet GTR9 with EEVC legform• Crushable bumper bar with space between fascia and beam (Yaris)• Modular energy absorber (Fusion)• Softer energy absorber combined with stiffer lower apron or “lower leg
catcher” (Focus, Passat, Cruze)
• These design strategies to meet EEVC IARV also meet FlexGTR IARV
BUMPER PART OBSERVATIONS
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SAE INTERNATIONAL
• Part 581 assumption: overseas versions would fail, North American versions would pass
• Full Part 581 series was not conducted; only frontal pendulum• Modified systems could have sustained damage in subsequent tests
• Countermeasures expected to provide comparable improvements across bumper width• Fusion: lower FlexGTR measures near test zone edge than at center
• Analysis limited to global passenger cars (no large vehicles)• MPVs and Trucks are currently exempt from Part 581 (74 FR 28210)
ASSUMPTIONS & LIMITATIONS
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SAE INTERNATIONAL
SUMMARY
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• Part 581, GTR9, and 581/GTR9 version bumper systems from five “global platform” vehicles tested
• One production & one slightly modified vehicle met both proposed FlexGTR IARV & Part 581 (frontal pendulum only) criteria with single bumper system• Modular EA, soft EA + stiff lower apron, and crushable bumper beam
were observed in GTR9-passing bumper systems
• Overseas systems designed to meet GTR9 with EEVC leg also did well with FlexGTR• Design strategies vary but none were drastic overhauls from NA system
• Of FlexGTR injury measures, tibia bending moment had strongest correlation with Part 581 pendulum forces
PERFORMANCE OF BUMPER SYSTEMS WITH RESPECT TO PEDESTRIAN PROTECTION AND BUMPER DAMAGEABILITY REQUIREMENTS
Jason StammenNHTSA
Brian SuntayTransportation Research Center Inc.
2014 SAE Government / Industry Meeting
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.