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The rate of energy absorption during the plastic deformation of structural components is an important factor in the design of automotive safety systems such as chassis crumple zones. This paper describes a design tool for predicting energy absorption characteristics. The tool was based on measurements of the energy absorption rates of twenty-three selected materials subjected to three impact energy conditions. A well-established finite element code, LS-DYNA3D, was used with a mesh representing a hollow column of square cross-section to establish a database of energy absorption characteristics. A mathematical model representing the energy absorption rates was determined and the material properties most influencing the energy absorption rates were identified. A parabolic model best represented the energy absorption charactersitics. The regression coefficients for the model were determined for all tested materials under the selected test conditions.

This study relates the structural stiffness and kinetic energy of impact (between 34 J and 136 J) to the resulting contact force and duration of force rise for a square tube with wall thickness between 12.7 mm and 25.4 mm. LS-DYNA3D, finite element program was used for the analysis. Two materials, AISI 4340 and AISI 301 steel, are used as examples. Regression equations for predicting the relationship between the structural stiffness, maximum force and duration of force rise are given for each material.