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The effect of strain rate in a full vehicle frontal crash analysis is investigated. The strain rate properties obtained from the Auto-Steel Partnership (A/S P) project are utilized in this investigation. Johnson-Cook material model that incorporates strain rate was used in the analysis. The analysis was done with and without strain rate using two vehicle front impact models. Results of the analysis were compared to the test data for deceleration and dynamic crush. The results from this study indicate that incorporating strain rate in the frontal crash analysis yields dynamic crush estimates that are closer to test results. Therefore, strain rate material coefficients should be considered for frontal crash analysis application.

The effects of strain-rate and element mesh size on the numerical simulation of an automotive component impacted by a mass dropped from an instrumented drop tower was investigated. For this study, an analysis of a simple steel rail hat-section impacted by a mass moving at an initial velocity of 28Mph was performed using the explicit finite element code Radioss. Three constitutive material models: Elasto-Plastic (without strain rate), Johnson-Cook, and Zerilli-Armstrong were used to characterize the material properties for mild and high strength steel. Results obtained from the numerical analyses were compared to the experimental data for the maximum crush, final deformation shape, average crush force and the force-deflection curve. The results from this study indicate that the mechanical response of steel can be captured utilizing a constitutive material model which accounts for strain rate effect coupled with an average mesh size of 6 to 9mm.