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Motor Vehicle safety regulations in the United States and other industrialized countries have evolved over the last three decades in order to meet the demands for increased traffic safety. The safety regulations that exist today are, in many respects, not harmonized. Because multiplicity of vehicle safety requirements do not allow manufacturers to use common vehicle designs across global markets and because the motor vehicle industry is more globalized now, there is the need for harmonized regulations more so now than ever before. At the same time, safety concerns related to human injuries and fatalities in passenger vehicles are similar in industrialized countries where a large number of vehicles are in use for transportation, in spite of differences in fleets and roadways. This paper examines the regulatory processes in the United States and Europe. It presents a cursory analysis of the existing vehicle safety standards to show the potential for harmonization.

A comparative study between belted rollover occupants who did and did not receive head injuries from roof contact was conducted using the National Accident Sampling System (NASS) database. The main objective was to determine if headroom reduction increases the risk of head injury. Headroom was determined for 155 belted occupants involved in rollover crashes of vehicles which were then weighted to make them representative of national estimates. Results showed that headroom was reduced more in those crashes where the occupant had head injuries than in cases where there were no head injuries. It was concluded that the risk of head injury increased with reduced headroom. Furthermore, it was observed that when the initial headroom was higher, the incidence of head injury was reduced.

The National Highway Traffic Safety Administration (NHTSA) upgraded the side impact protection requirement in Federal Motor Vehicle Safety Standard (FMVSS) No. 214 and added dynamic requirements to reduce the likelihood of thoracic injuries in side crashes. As part of the agency's research in developing the requirements of the standard, NHTSA developed a mathematical model for simulation of side impacts. This paper investigates the overall safety performance, based on Thoracic Trauma Index (TTI) as the criteria for passenger cars in real world side crashes, with the aid of the simulation model. A Thoracic Trauma Index Factor (TTIF) is utilized to compare relative safety performance of passenger cars under various conditions of impact. The concept of relating energy dissipation in various side structure and padding countermeasures is used to develop a family of curves that are representative of a design platform.

The National Highway Traffic Safety Administration (NHTSA) has developed a lumped mass computer model which simulates the interaction of a struck car door and an adjacent two dimensional seated dummy in side impacts. This model was used to investigate the effect of various vehicle design parameters on occupant responses and to define various methods to improve vehicle safety performance. This paper discusses the effectiveness of door padding and side structural stiffness to minimize potential for occupant thoracic injuries in 90° side impacts. Occupant response data were obtained with the aid of the computer model for a Moving Deformable Barrier striking a car at lateral velocities of 25, 30 and 35 mph. To determine the optimal padding and structure needed to minimize potential occupant injury, the Thoracic Trauma Index (TTI) was mapped in terms of different levels of struck car side stiffness and padding characteristics.

Since the 1984 publication of the results of NHTSA's initial research on thoracic side impact protection, substantial progress has been made. Specifically, the NASS data have been reviewed relative to side impacts, an updated injury criterion has been developed, the MVMA has conducted a very significant crash test project, and the NHTSA has conducted additional full system production vehicle tests. The review of the NASS data and a comparison with the previously used NCSS data indicate the thoracic injury remains the highest ranking injury in non-rollover, non-ejection side impacts. The updated injury criterion, TTI-86, is applied to the side impact dummies in the modified vehicle tests which have been conducted by NHTSA and MVMA. The TTI-86 is also applied to twenty production vehicle tests which have been conducted by NHTSA. The improved performance of the modified vehicles is compared to the average performance of the twenty production vehicles.

Lumped spring/mass modelling approaches are described for the simulation of structural and occupant response in side impacts (driver side). Special attention is placed on modelling techniques and procedures for mass assignments, derivation of force versus deflection characteristics and model redundancy checks. The force versus deflection characteristics were derived from dynamic test data and the inverse solution of the nonlinear equations of motion for the system. Unique procedures are also presented for estimating rib to spine damping characteristics and driver body segment internal and contact compliances. Three models are presented and evaluated. Simulations showing the effect of changes in striking car stiffness, struck car stiffness-, impact angle, impact speed, occupant to door clearance and interior door pad thickness and strength are presented and discussed. Model limitations and various factors affecting the applicability of the methodology are also discussed.

Results of a sensitivity study, based on lumped spring/mass modeling approaches for the characterization of structural and occupant responses in 60° and 90° side impacts, are presented in this paper. Test data from collisions between a moving deformable barrier (MDB) and the side of a Volkswagen Rabbit in two crash configurations, simulating 60° and 90° impacts, are used to derive the force-deflection characteristics of the nonlinear springs in the model. The mathematical model is used to investigate the sensitivity of occupant responses to parametric changes in the striking and struck car characteristics. The variables included in this parametric study are striking vehicle and struck vehicle stiffnesses, crash configuration, impact velocity, occupant-to-door clearances, and padding characteristics. The striking car and struck car side stiffnesses are varied in the range of ±40 percent and ±30 percent, respectively, from the nominals.