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An Update on NHTSA’s Small Overlap/Oblique
Research Program
James Saunders, NHTSA
1
Presentation Order
• Background
• Vehicle selection
• Constant-energy RMDB-to-vehicle test results
– Small Overlap Impact (SOI)
– Oblique
– Compare SOI to Oblique
2
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
Background
• 2000-2007 NASS fatalities for model year vehicles 2000+ where occupant was restrained
3 This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
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
4
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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
5
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
SOI: Test Setup
6
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)
7
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SOI: Compact Vehicle Top View
8 This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
SOI: Compact Dummy Kinematics
9 This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
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
10
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)
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
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
11
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
12
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
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
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
13
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)
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.
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
14
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
15
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Oblique: Test Setup
16
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
17
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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
18
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
19
-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)
20
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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
21
This is a U.S. Government Work not subject to copyright protection in the U.S. It may be copied and distributed without permission and without limitation.