For the past several years, the National Highway Traffic Safety Administration (NHTSA), has conducted research on thoracic protection in side impacts. As part of this researcha lumped mass computer model was developed for simulating side crashes. This model has been exercised extensively to simulate the interaction of the struck car door and the occupant in side impacts. Simulation studies were also undertaken to investigate the effects of various vehicle design parameters on occupant responses.

This paper analyzes the performance differences seen in eight production vehicles tested with the NHTSA side impact test procedure, with the aid of this model. The energy absorption in various parts of the side structure of the struck car, the striking barrier and the occupant represented in the model were computed for the passenger car tests simulated. The results showed that increased energy dissipation in the struck vehicles generally yielded lower Thoracic Trauma. Index (TTI). Viscous Criterion (VC) showed a similar trend for absorbed energy in the door core due to thorax contact. However, such energy dissipation in certain components alone does not assure that the desired vehicle or occupant response to effectively reduce the TTI measured on the dummy (TTl(d)). Instead, the appropriate sharing of the energy in an optimum manner among the various interacting components is essential to achieve the lowest possible TTI(d).

A mathematical relationship between the energy dissipated in three of the major structural components in the model and the TTI(d) has been derived knowing the energy dissipation distribution for the eight vehicle tests simulated. This relationship is utilized to present a set of useful curves which will enable the user to select energy absorption levels for various components of the side structure when TTI(d) level desired for a particular vehicle design is known.