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The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. This paper is the fourth in a series of technical papers intended to disseminate the results of the ongoing research [Digges 2004, 2005, 2006]. This paper summarizes progress in several of the projects to better understand the crash factors that are associated with crash induced fires. Part I of the paper presents the distribution of fire cases in NASS/CDS by damage severity and injury severity. It also examines the distributions by crash mode, fire origin, and fuel leakage location. The distributions of cases with fires and entrapment are also examined. Part II of the paper provides summaries of recent projects performed by MVFRI contractors. Technologies to reduce fuel leakage from siphoning and rollover are documented.

Rollover crashes continue to be a serious and growing vehicle safety problem. Rollovers account for about 9% of passenger car crashes, and 26% of light truck crashes. Belt use in rollover crashes is about 51%, compared with 62% in planar crashes. Overall, 26.4% of the serious and fatal injuries to occupants exposed to crashes are in rollovers. Among this injured population 74.4% are unbelted. In light trucks, rollovers account for 47.4% of the serious or fatal injuries. Unbelted occupants suffer about 87% of the serious injuries and fatalities in light truck rollovers. The use of safety belts offers a dramatic reduction in injury rates for rollover crashes. For belted occupants of pickup trucks and utility vehicles in rollover crashes, the injury rates are about the same as for belted occupants of passenger cars in planar crashes. Improvementsts in safety belts offer large opportunities in safety.

The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. In a subsequent Judicial Settlement, GM agreed fund more than $4.1 million in fire related research over the period 2001-2004. The purpose of this paper is to provide a public update report on the projects that have been funded under this latter research program, along with results to date. An analysis of FARS and State accident data has been completed. Results indicate that fire rates have been significantly reduced over the past 20 years. Fire rates for passenger cars and LTVs have approached similar levels. Fire rates by crash mode indicate that rear impact fires have been significantly reduced; however, fires in rollover crashes have seen considerably less reduction. The highest percentages of fires are subsequent to frontal impacts.

Real world crashes in NASS/CDS 1997 to 2000 were examined individually in order to find patterns in single vehicle rollover crashes. Typical maneuver induced rollovers of SUV's were reconstructed using the HVE model. From HVE and roll event reconstructions, the values of longitudinal, lateral, and vertical displacement, and roll, pitch, and yaw angle, for the pre-roll and rollover event were calculated. These values were used as inputs to a MADYMO model for simulated vehicle motion to predict occupant kinematics. Both near-side and far-side rollovers were simulated. The MADYMO model provided estimates of head velocity for the various rollover scenarios for a belted driver. In both near-side and far-side rollovers of the type reconstructed, the lateral component of head velocity was the greatest. Maximum head velocities of 5.3 m/s were predicted. The simulations were for two complete rollovers. The highest head velocity occurred during the first three quarter turns.

This paper uses the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) to estimate the population of front seat occupants exposed to far-side crashes and those with MAIS 3+ and fatal injuries. Countermeasures applicable to far-side planar crashes may also have benefits in some far-side rollovers. The near-side and far-side rollover populations with MAIS 3+ injuries and fatalities are also calculated and reported. Both restrained and unrestrained occupants are considered. Populations are subdivided according to ejection status – not ejected, full ejection, partial ejection and unknown ejection. Estimates are provided for the annual number of MAIS 3+ injuries and fatalities that occur each year in each category for the following belt use scenarios: (1) belt use as reported in NASS and (2) 100% belt use. In scenario 1, the exposure and casualties for the unbelted population are also shown. About 34% of the MAIS 3+F injuries in side crashes are in far-side crashes.

The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. This paper is the third in a series of technical papers intended to disseminate the results of the ongoing research [Digges 2003 and 2004]. This paper summarizes progress in several of the projects. A statistical analysis of FARS and NASS/CDS indicates that frontal collisions are the most common in both fatal and non-fatal crashes with fires. NASS/CDS indicates that most major and minor fires originate under the hood. Fire rates in FARS are higher in rollovers than in planar crashes, and most rollover fires in NASS/CDS originate under the hood.

Seventeen full-scale crash tests were conducted to evaluate technologies to reduce the vulnerability of sidesaddle tanks on full size GM pickup trucks manufactured during the period 1973-1987. These vehicles were alleged by the U.S. Department of Transportation to be vulnerable in severe side impacts. The test program was intended to evaluate designs that would reduce vulnerability in all crash directions. The best test results were obtained by two strategies that relocated the tank to less vulnerable locations. The two locations were: (1) in the cargo bed (bed mounted tank) and (2) underneath the bed, ahead of the rear axle and between the frame rails (center-mounted tank). Tanks mounted in these locations were subjected to a series of crash tests that simulated severe front, side, rear and rollover crashes. The crash environment for these tests was more severe than required by FMVSS 301 “Fuel System Integrity”.

Different roof strength methods are applied on the 2003 Ford Explorer finite element (FE) model to achieve the current Federal Motor Vehicle Safety Standard (FMVSS) 216 requirements. Two different modification approaches are utilized. Additionally, the best design of each approach is tested dynamically, in rollover and side impact simulations. In the first approach, several roll cage designs are integrated in all pillars, roof cross-members, and in the side roof rails. A roll cage design with a strength-to-weight ratio (SWR) of 3.58 and 3.40 for driver and passenger sides, respectively, with a weight penalty of 18.54 kg is selected for dynamic test assessments. The second approach investigates different localized reinforcements to achieve a more reasonable weight penalty. A localized reinforcement of the B-pillar alone with a tube meets the new FMVSS 216 requirements with a weight penalty of 4.52 kg and is selected for dynamic analyses.

This paper uses NASS/CDS 1997-2004 to determine the crash factors that are most frequently associated with rollover fires. Rollover fire cases were analyzed by the NASS variables including vehicle type, fire origin, number of quarter-turns, and final rest position. Results show that the engine compartment was the most frequent location for the fire origin. The fuel tank was second in this category. The rest position on the roof was most frequently associated with fires in rollovers. However, the fire rate was not strongly influenced by the final rest position. High severity rollovers that involve more than eight quarter-turns or end-over-end motion had fire rates much higher than the average. An examination of 24 cases with major fires in recent model year vehicles found that impacts prior to the rollover occurred in more than half of the cases. All of the cases with leakage from the fuel tank had impacts prior to the rollover.