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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.

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.