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

2

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

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

SAE INTERNATIONAL

SUMMARY

13

• 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.