Equivalent Energy Absorption (EEA) - A Methodology for Improved Automotive Crash & Safety Design

Safety norms across the world are becoming more and more stringent posing new challenges to achieve lightweight vehicle structures. Structures made of Advanced/Ultra high strength steels (AHSS) play a vital role in meeting the vehicle safety targets, by absorbing large amounts of impact energy, as well as by withstanding higher impact loads that occur due to vehicle collisions. Safety simulations usually take longer solution times due to their complexity and nonlinear nature. Engineers often encounter with a problem of quick evaluation of safety performance by using different grades of materials to optimize the weight & cost. In this paper, a new methodology - Equivalent Energy Absorption (EEA) has been proposed to do a quick trade-off study on performance vs weight for various thickness and material combinations. A relationship is established between the gauge and grade of a component to derive an equivalent safety performance so that engineers can make quick decisions by conducting minimal number of simulations. a simple rectangular crush box was considered for study to assess the Energy Absorption (EA) with various material and thickness combinations. A Design of Experiments (DOE) study was done using simulations with many numbers of material grades and gauges to construct a 3D Response Surface between gauge, grade & EA parameters to understand the relationship between each of these parameters. A case study has been discussed in the paper about application of this methodology on a vehicle to evaluate its safety performance. It has been found that more than 80% evaluation time is reduced by using this methodology.