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Occupant simulation models have been used to study trends or specific design changes in “typical” accident modes such as frontal, side, rear, and rollover. This paper explores the usage of the Articulated Total Body Program (ATB) as an accident reconstruction tool. The importance of model validation is discussed. Specific areas of concern such as the contact model, force-deflection data, occupant parameters, restraint system models, head/neck loadings, padding, and intrusion are discussed in the context of accident reconstruction.

The issues of front seat energy absorption and seat belt effectiveness are investigated first through the review of prior experimental and analytical studies of rear impact dynamics. These prior studies indicate that the current energy absorption characteristic of seats is a safety benefit. Prior efforts to construct a rigidized seat indicate that such designs are likely to be impractical due to excessive weight and cost. Additionally, these studies indicate that seat belts provide an important safety function in rear impacts. Static tests of production seats were conducted, added to an existing data base, and analyzed to better understand the strength and energy absorbing characteristics of production seats. Crash test results from the New Car Assessment Program as well as earlier test programs were analyzed to describe the response of occupants and seats in rear impact and the protective function of seat belts in such collisions.

Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. The evolution of the CRASH model of vehicle structural response and its corresponding stiffness coefficients are reviewed. It is concluded that the deformation energy for an accident vehicle can be estimated using the CRASH model provided that test data specific to the accident vehicle is utilized. Published stiffness coefficients for vehicle size categories are generally not appropriate. For the purpose of estimating vehicle deformation energy, a straight-forward methodology is presented which consists of applying the results of staged crash tests. The process of translating crush profiles to estimates of vehicle deformation energies and velocities is also discussed.