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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.

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.

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.