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In vehicle crash tests, an unbelted occupant's kinetic energy is absorbed by the restraints such as an air bag and/or knee bolster and by the vehicle structure during occupant ride-down with the deforming structure. Both the restraint energy absorbed by the restraints and the ride-down energy absorbed by the structure through restraint coupling were studied in time and displacement domains using crash test data and a simple vehicle-occupant model. Using the vehicle and occupant accelerometers and/or load cell data from the 31 mph barrier crash tests, the restraint and ride-down energy components were computed for the lower extremity, such as the femur, for the light truck and passenger car respectively.

The vehicle-occupant impact dynamics during a crash are studied using a simple mathematical model. The model yields explicit analytical relationships between occupant responses and physical parameters of the vehicle structure and occupant restraint system. These parametric relationships, verified by experimental crash tests of the total system, are useful in describing the physical concepts of the impact event, and predicting occupant dynamic behavior during a vehicle crash. The limitations of the model are discussed and the design procedures using the equations and “carpet” plots are presented to aid the designer in the selection of a restraint system and vehicle structural parameters to meet predetermined design criteria. The application of the “carpet” plot in studying the sensitivity of the occupant response to the vehicle structural parameters is also demonstrated.

It is frequently desirable to construct a characterization of vehicle deceleration which is significantly simplified from its actual time history. A number of interesting techniques have been developed to perform this characterization based upon polynomial and Fourier-type series approximations and utilizing goodness of fit criteria related to both least squared error and the satisfaction of boundary conditions. Extensive mathematical occupant simulations indicate that characterizations involving as few as four parameters are adequate to describe the primary effects of complex vehicle deceleration time histories as they influence occupant dynamics with conventional restraint systems.

This paper reports a study of the dynamic characteristics of body mounts in body on frame vehicles and their effects on structural and occupant CAE results. The body mount stiffness and damping are computed from spring-damper models and component test results. The model parameters are converted to those used in the full vehicle structural model to simulate the vehicle crash performance. An effective body mount in a CAE crash model requires a set of coordinated damping and stiffness to transfer the frame pulse to the body. The ability of the pulse transfer, defined as transient transmissibility[1]1, is crucial in the early part of the crash pulse prediction using a structural model such as Radioss[2]. Traditionally, CAE users input into the model the force-deflection data of the body mount obtained from the component and/or full vehicle tests. In this practice, the body mount in the CAE model is essentially represented by a spring with the prescribed force-deflection data.