POWERPOINT PRESENTATION - APRIL 3, 2003


SLIDE 1
THE RELATIONSHIP BETWEEN CRASH SEVERITY AND INCOMPATIBILITY IN FRONTAL CRASHES

A CIREN CENTER
THE WILLIAM LEHMAN INJURY RESEARCH CENTER
Jeffrey S. Augenstein, Kennerly Digges, George Bahouth., James Stratton, Elana Perdeck, Jerry Phillips, Jeffrey Mackinnon, and Luis Labiste, M.D. Professor of Surgery - Director, WLIRC

SLIDE 2
Incompatibility Issues
Mass difference is a well known incompatibility
Other incompatibilities - Stiffness & Geometry
Regulations to control stiffness and geometry under consideration
What role does stiffness and geometry play in real world crashes?
Would control of stiffness and geometry in barrier crashes provide real world benefits?


SLIDE 3
Past NHTSA Research
Analysis of FARS car to truck crashes showed passenger cars occupants at disadvantage

Barrier crash data shows light trucks are stiffer and have higher center of force

 

SLIDE 4
NCAP Test into Load Cell Barrier


SLIDE 5
 NHTSAs Load Cell
 Barrier Face


SLIDE 6
Barrier Force Data 250mm Crush
Dodge Neon vs Grand Cherokee


SLIDE 7
Barrier Footprint - 250 mm Crush


SLIDE 8
Definition of Force Center
F is Resultant Force
H is  Force Center


SLIDE 9
scatter chart:
Stiffness and Center of Force from NCAP Barrier Force Measurements 


SLIDE 10
Comparison Of Load Cell Barrier Forces for Typical Car and LTV
Examination of Barrier Force Compatibility in the B Row


SLIDE 11
Barrier Force -Neon


SLIDE 12
Barrier Force - cherokee


SLIDE 13
Barrier Force vs. Vehicle CrushAll Load Cell Rows


SLIDE 14
Barrier Force vs. Vehicle CrushOnly B Load Cell Row


SLIDE 15
Observation
- Max force of most cars in B row

- May produce forces of greater magnitude than SUV forces in the B row

- Mismatch may reduce stiffness mismatch in lower severity crashes  until occupant compartment intrusion occurs

- Injuries will be intrusion related rather than acceleration related
Lower limbs most vulnerable


SLIDE 16
Research Questions
Does the higher center-of-force on light trucks lead to reduced injury risk in cars when the crash severity is low?
What happens to the injury risk in high severity car-to-LTV crashes?
What is the role of intrusion vs. acceleration in car-to-LTV crashes?


SLIDE 17
Data for NASS/CDS StudySAE 2001
1997 & 1998 Car to LTV Frontal Crashes
Crush Measurements on Both Vehicles
Pictures of Both Vehicles
Delta-V Known for Both Vehicles
Injury Data for Occupants Available
44 Cases
23 with MAIS 3+ Injuries to Car Drivers


SLIDE 18
NASS Case Study of Car Drivers23 Cases with MAIS 3+
9 injuries with no compatibility influence
5 cases with injuries explained by mass
5 cases in which geometry or stiffness were influential factors increasing injuries
4 cases in which geometric incompatibility may have decreased or prevented injuries
All MAIS 3+ injuries at lower Delta-V were lower limb injuries




SLIDE 19
Examination of Frontal Crashes in NASS 1997-2000
Distribution
Injury risk 

Car-to-car
Car-to-LTV

Above 20 mph
Below 20 mph


SLIDE 20
Distribution of Crashes Above and Below 20 mph


SLIDE 21
Injury Rate for Car-to-Car and Car-to-LTV Frontal Crashes


SLIDE 22
Crash Investigation to Examine Effect of Geometric and Stiffness Compatibility
To evaluate the effect of stiffness and geometry
Need to collect data on POV
Need to document underride/override
Need to evaluate frequency of intrusion vs acceleration injuries
Need to document frame deformation modes


SLIDE 23
photo: Ramrod Effect of Frame


SLIDE 24
photo: Vehicle Override


SLIDE 25
Lehman Center Cases to Examine LTVs in Frontal Collisions with Passenger Cars 


SLIDE 26
MODERATE SEVERITY CRASH

1998 Chrysler Sebring
VS
2001 Ford F-250


SLIDE 27
CASE SUBJECT

 Passenger
 Belted
 Air bag deployed
 Female
 54 years old 
 185lbs
 55

Case subject was traveling 
with spouse when crash occurred



SLIDE 28
SCENE
case vehicle - 1998 Chrysler Sebring LXI
POV: 2001 Ford F-250 SuperCap 4x4
south approach


SLIDE 29
EXTERIOR CHRYSLER SEBRING DAMAGE
Right side - Reduction in wheelbase 6.7 


SLIDE 30
Exterior Chrysler Sebring Comparison


SLIDE 31
Interior Chrysler Sebring Damage
Left front overview
Passenger area with Leg
Passenger toepan intrusion 13 


SLIDE 32
Interior Chrysler Sebring Comparison


SLIDE 33
Injuries


SLIDE 34
Glove box door - Left femur fracture AIS 3


SLIDE 35
Toepan - Left tib/fib fracture AIS 2


SLIDE 36
Toepan - Right ankle fracture AIS 2


SLIDE 37
CONTACTS SUMMARY
* Fracture, Right Midshaft Femur - AIS 3 - Glove Box Door
* Fracture, Left Distal Tibia - AIS 2 - Right Toe pan
* Fracture, Left Distal Fibula - AIS 2 - Right Toe Pan
* Fracture, Right Ankle	- AIS 1	- Right Toe Pan
* Contusion, Right Knee	- AIS 1 - Glove Box Door
* Fracture, Left Rib - AIS 1 - Belt Restraint
* Contusion, Left Breast - AIS 1 - Belt Restraint


SLIDE 38
Comparison of Vehicle Dimensions

1998 Chrysler Sebring	
Bumper Height:	25	
Frame Rail Upper:	20.25	
Frame Rail Lower:	16.5		
Mass:			2908lb	
Stiffness: Moderate 


2001 Ford F-250
Bumper Height:	31.25
Frame Rail Upper:	29
Frame Rail Lower:	23.5
Mass:			5635lb
Stiffness: Very High


SLIDE 39
Case Significance
25 mph crash with 
13 of pass toepan intrusion
0 of driver toepan intrusion

Driver OK  low intrusion

Passenger with lower extremity injuries due to intrusion

No head or chest injuries

Incompatibility increased intrusion

Incompatibility may have prevented head and chest injuries to driver and passenger


SLIDE 40
Moderate Severity Crash
2000 Nissan Maxima VS 1996 Ford Aerostar


SLIDE 41
Case Subject

 Driver
 Male
 Unbelted
 Air bag deployed
 45 years old
 185lbs
 511

Case subject was under the influence of alcohol when this late night crash occurred


SLIDE 42
SCENE
Nissan Maxima on north approach


SLIDE 43
Exterior Nissan Maxima Damage
DeltaV:	 25.6mph
Max crush: 18.1
Position: C6
PDOF: 	1 oclock
Wheelbase Pre: 108.1 	Post: 101.9

Reduction:6.4



SLIDE 44
photos: Exterior Nissan Maxima Damage

SLIDE 45
photos: Exterior Nissan Maxima Comparison


SLIDE 46
photo: lateral view of steering wheel from right


SLIDE 47
Interior Nissan Maxima Comparison
 - np driver toepan inturusion!

SLIDE 48
INJURIES


SLIDE 49
INJURY OVERVIEW


SLIDE 50
Contacts Summary
Fracture, Left & right femurs - AIS 3 - Knee bolster
Fracture, Left 5th & 6th Rib - 	AIS 2 - Driver air bag
Abrasion, Forehead - AIS 1 - Windshield
Abrasion, Right elbow - AIS 1 - Windshield
Abrasion, Left & right shin - AIS 1 - Left instrument panel and below



SLIDE 51
Contacts Summary

Fracture, Left & right femurs - AIS 3 - Knee bolster
Fracture, Left 5th & 6th Rib - AIS 2 - Driver air bag
Abrasion, Forehead - AIS 1 - Windshield
Abrasion, Right elbow - AIS 1 - windshield 
Abrasion, Left & right shin - AIS 1 - Left instrument panel and below



SLIDE 52
Comparison of Vehicle Dimensions

2000 Nissan Maxima
Bumper Height:	28.25
Frame Rail Upper: 21.5
Frame Rail Lower: 15.5	
Mass: 3294lb
Stiffness: Moderate 


1996 Ford Aerostar
Bumper Height: 23
Frame Rail Upper: 21.5
Frame Rail Lower: 15.75
Mass: 3500lb
Stiffness:High


SLIDE 53
Case Significance

 45 Year old Driver in 25+ mph delta V

 5.1 right toepan intrusion 
(No toepan intrusion on left)
 Left Femur Fracture- AIS 3
 Rib Fracture  AIS 2
Good geometric and mass compatibility
Intrusion not an issue

 Stiffness incompatibility may have contributed
 to the injury



SLIDE 54
HIGH SEVERITY CRASH
1996 Hyundai Accent VS 1997 Kia Sportage


SLIDE 55
CASE SUBJECT
 Driver
 Female
 Unbelted
 Air bag Deployed
 23 years old
 140lbs
 57


SLIDE 56
SCENE:
case vehicle 1996 hyundia accent
POV: 1997 Kia sportage


SLIDE 57
EXTERIOR HYUNDAI ACCENT DAMAGE
DeltaV: 35mph
Max crush: 33
Position: C1
PDOF: 12 oclock

Wheelbase Pre: 95.4	Post: 71

Reduction: 24.4



SLIDE 58
EXTERIOR HYUNDAI ACCENT COMPARISON

SLIDE 59
HYUNDAI ACCENT EXTERIOR DAMAGE
DeltaV: 24mph
Max crush: 27	
Position: C1
PDOF: 12 oclock		
Wheelbase
	Pre: 104.3	Post: 87
Reduction: 17



SLIDE 60
comparison of vehicles:
case vehicle hyundai accent.
POV - kia sportage


SLIDE 61
photo: interior hyundai accent comparison


SLIDE 62
photo: interior hyundai accent damage - right front overview


SLIDE 63
photo: interior hyundai accent damage - insturment panel


SLIDE 64
photo: interior hyundai accent damage - left instrument panel intrusion 15"


SLIDE 65
photo: interior hyundai accent damage - driver area overview. toepan intrusion 18.5"

SLIDE 66
photo: interior hyundai accent damage - knee bolster

SLIDE 67
photo: interior hyundai accent damage - driver air bag


SLIDE 68
photo: interior hyundai accent damage - steering wheel


SLIDE 69
photo: interior hyundai accent damage - driver area overview


SLIDE 70
INJURIES


SLIDE 71
Injury Overview



SLIDE 72
A pillar - AIS 3 - left radius & ulnar fx


SLIDE 73
photo: knee bolster - AIS 3 - left femur fx


SLIDE 74
photo: left side interior surface - AIS 2 - bilateral inferior pubis rami fx


SLIDE 75
photo: Left side interior surface - AIS 3 - left radius & ulnar fx


SLIDE 76
Contacts Summary

Fracture, Left femur - AIS 3 - Knee bolster	
Fracture, Left ulna - AIS 3 - Left A pillar
Fracture, Left radius - AIS 3 Left A pillar
Fracture, Third cervical vertebra - AIS 3 - Left A pillar
Hemorrhage, Subarachnoid space - AIS 3 - Left A pillar 
Contusion, Frontal Lobe	- AIS 3 - Left A pillar


SLIDE 77
Contacts Summary

Fracture, Anterior maxilla - AIS 2 - Left A pillar
Fracture, Fourth cervical vertebra - AIS 2 - Left A pillar
Laceration, Spleen - AIS 2 - Left side hardware & armrest
Fracture, Bilateral pubis rami - AIS 2 - Left side interior surface excluding hardware & armrest



SLIDE 78
Comparison of Vehicle Dimensions
1996 Hyundai Accent		
Bumper Height:	 21		
Frame Rail Upper: 19.75	
Frame Rail Lower: 15			
Mass:	2105lb	 
Stiffness: Moderate 

1997 Kia Sportage
Bumper Height: 25.5
Frame Rail Upper: 19
Frame Rail Lower: 15.25
Mass: 3280lb
Stiffness: Moderate


SLIDE 79
Case Significance
Two vehicles with good geometric 
 and stiffness compatibility

Differences in vehicle masses 2100 vs 3300

Lesson: Matching geometry and stiffness may not compensate for mass differences



SLIDE 80
Conclusions
Low and moderate severity cases with poor geometric compatibility have primarily lower limb injuries

Intrusion of the toepan is frequently, but not always a factor in lower extremity injuries

High severity case had good geometric compatibility  mass difference was a primary factor for extensive intrusion - injuries



SLIDE 81
Observations
Control of stiffness and geometry may not offset mass differences

Geometric mis-match may be beneficial at lower DeltaV  Until intrusion occurs

Stiffness and geometry control need to consider load in the B row

Further analysis of CIREN cases would be beneficial to understanding compatibility


SLIDE 82
Lehman Incompatibility Investigation Procedures
Developed methods of documenting structural interaction in front-to-front crashes between cars and light trucks
Underride and override
Ram-rod damage the stiff frame
Bending vs. compression of frame elements
Crashes that are unlike barrier crashes
Unexpected outcomes




SLIDE 83
Recommendations
Analysis of CIREN cases needed to understand the role of stiffness and geometry in real world crashes
Enhanced case documentation required
POV capture and documentation necessary
Incorporate NCAP data on stiffness and geometry