An Update on NHTSA’s Small Overlap/Oblique

Research Program

James Saunders, NHTSA

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Presentation Order

• Background

• Vehicle selection

• Constant-energy RMDB-to-vehicle test results

– Small Overlap Impact (SOI)

– Oblique

– Compare SOI to Oblique

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Background

• 2000-2007 NASS fatalities for model year vehicles 2000+ where occupant was restrained

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Vehicle Selection

• Vehicles introduced or redesigned in 2010-2011

• Good structural rating from IIHS

• Different classes of vehicles ranging from the lightest to the heaviest

• Compare heavy vehicle with body-on-frame and uni-body design

• 8 SOI and 7 Oblique

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Constant-energy test procedure

• Moving deformable barrier impacts each vehicle at the same velocity

– Compare results across the fleet

– Procedure is more severe for smaller cars

– Potential to drive convergence of vehicle front-end stiffness

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SOI: Test Setup

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Small Overlap (SOI) Rationale

Barrier Closing Speed 56 mph Achieve 35mph Delta-V in average-

mass passenger car

Overlap 20% Engage structure outboard of

longitudinal rail for most vehicles

Angle Relative to Track 7 degrees 0 degrees bounced off

15 degrees deformed rail inboard

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Occupant Response Assessment: THOR ATD

• THOR-NT with Mod Kit – Improvements to biofidelity, repeatability,

durability, usability

• Designed to demonstrate improved biofidelic kinematics vs. Hybrid III – Flexible joints in thoracic, lumbar spine – Improved restraint interaction

• Increased measurement capability vs. Hybrid III – Thorax: 4-point, 3-dimensional chest deflection – Abdomen: 2-point, 3-dimensional lower

abdomen deflection – Knee-thigh-hip: Acetabulum load cells – Lower Extremity: Upper, lower tibia loads; ankle

rotations

• Provisional Injury Assessment Reference Values (IARVs)

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SOI: Compact Vehicle Top View

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SOI: Compact Dummy Kinematics

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SOI: Change in Velocity

• Fixed-mass, fixed-velocity RMDB-to-vehicle impact results in responses sensitive to vehicle mass – Lighter vehicles – Earlier velocity onset – Larger total Delta-V

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Lighter

Heavier

Average

Passenger

Car (3300 lbs)

-70

-60

-50

-40

-30

-20

-10

0

10

0 0.05 0.1 0.15

SO

I X

-Velo

cit

y (

kp

h)

Time (seconds)

RAM 1500 (5744 Lbs)

Explorer (5196 Lbs)

LaCrosse (4259 Lbs)

Fusion (3700 Lbs)

Cruze (3615 Lbs)

Fiesta (3003 Lbs)

Yaris (2930 Lbs)

Smart (2273 Lbs)

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SOI: Intrusion

• No apparent trend in intrusion vs. vehicle mass

• Toepan – Highest intrusion in

heaviest vehicle

• Door – In most cases, door

frame intrusion → door panel outward deformation

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0

50

100

150

200

250

300

Toepan IP Left IP Right SW Door

SO

I In

tru

sio

n (m

m)

Intrusion Point

RAM 1500 (5744 Lbs)

Explorer (5196 Lbs)

LaCrose (4259 Lbs)

Fusion (3700 Lbs)

Cruze (3165 Lbs)

Fiesta (3003 Lbs)

Yaris (2930 Lbs)

Smart (2273 Lbs)

Marginal or Poor

Acceptable or Good

IIHS Structural Rating

In ODB Procedure

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SOI: Head Response

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0.0

0.2

0.4

0.6

0.8

1.0

1.2

HIC15

ForTwo

Yaris

Fiesta

Cruze

Fusion

LaCrosse

Explorer

Ram1500

IAV

/ IA

RV

Test: Head Contact Locations

Vehicle Airbag

Side

Curtain

Roof

Rail

Door

Panel IP

1 X

2 X X X X

3 X X X

4 X X

5 X

6 X X

7 X X

8 X

Field Injury

Source (Rudd, 2011)

4% 28% 12%

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

BRIC

ForTwo

Yaris

Fiesta

Cruze

Fusion

LaCrosse

Explorer

Ram1500

IAV

/ IA

RV

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SOI: Chest Deflections • NASS/CIREN SOI: Chest injury sources

– Belt: 38% – Door: 32% – Steering wheel: 16%

• SOI Tests: Chest deflection sources

– Primarily belt interaction – No evidence of door contact – Door often deformed outward – Evidence of steering wheel interaction in smaller vehicles

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0.0

10.0

20.0

30.0

40.0

50.0

60.0

CMAX

ForTwo

Yaris

Fiesta

Cruze

Fusion

LaCrosse

Explorer

Ram1500Ch

est D

eflection

(m

m)

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SOI: Knee-Thigh-Hip • 4 test exceeded acetabulum IARV • 2 tests exceeded femur IARV • 2 tests that exceeded acetabulum IARV did not exceed

femur IARV – Rudd (2011) showed that over half of acetabulum injuries

occurred in absence of femur injury

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

AcetabL AcetabR

ForTwo

Yaris

Fiesta

Cruze

Fusion

LaCrosse

Explorer

Ram15000.0

0.5

1.0

1.5

2.0

2.5

3.0

FemurL FemurR

ForTwo

Yaris

Fiesta

Cruze

Fusion

LaCrosse

Explorer

Ram1500

IAV

/ IA

RV

IAV

/ IA

RV

Mass Mass

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SOI: Summary

• Delta-V sensitive to vehicle mass

– Lighter vehicles show higher DV

– DV range: 44-64 kph (27-40 mph)

• Large toepan, IP, and steering wheel intrusion

• Some vehicles showed high Injury risk in KTH, chest, head, lower extremity

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Oblique: Test Setup

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Oblique Rationale

Barrier Closing Speed 56 mph Achieve 35mph Delta-V in average-

mass passenger car

Overlap 35% Represent vehicle-to-vehicle test with

50% overlap (engagement of one longitudinal rail)

Angle Relative to Track 15 degrees PDOF of 10-20 degrees most

prominent in field after full frontal

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Oblique: Vehicle Top View

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Total DV • Delta-V decreases with increasing vehicle weight

• X-axis (longitudinal) Delta-V slightly higher for SOI

• Y-axis (lateral) Delta-V slightly higher for SOI

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0

10

20

30

40

50

60

70

To

tal D

V Y

(K

ph

)

SOI

Oblique

Longitudinal Lateral

0

10

20

30

40

50

60

70

SO

I To

tal D

V X

(K

ph

)

SOI

Oblique

1 2 3 4 5 6 7 81 2 3 4 5 6 7 8

Mass Mass

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Comparison: Difference in Intrusions

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-200

-150

-100

-50

0

50

100

150

Toepan IP Left IP Right SW Door

Ob

liq

ue-S

OI I

ntr

usio

n (m

m)

Intrusion Point

RAM 1500 (5744 Lbs)

Explorer (5196 Lbs)

LaCrose (4259 Lbs)

Cruze (3165 Lbs)

Fiesta (3003 Lbs)

Yaris (2930 Lbs)

Smart (2273 Lbs)

Oblique > SOI

SOI > Oblique

Mass

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SOI vs. Oblique Summary

• Vehicle response

– Delta-V: SOI slightly higher

– Intrusion: SOI consistently higher (except toepan)

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Thank You

• More details in the paper “Moving Deformable Barrier Test Procedure for Evaluating Small Overlap/Oblique Crashes” to be published at the 2012 SAE World Congress

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