An Analysis of Trends of Vehicle Frontal Impact Stiffness

This paper describes how impact induced vehicle residual deformation serves as a basis for the reconstruction engineer in making a determination of the energy absorbed during the impact phase of a collision. Many impact phase reconstruction algorithm s assume a liner relation between an absorbed energy function and residual crush in order to derive collision severity (Delta V, BEV, etc.). This is done through the assumption of a constant spring stiffness value to describe the vehicle frontal impact stiffness. However, some recent rigid barrier impact test data has demonstrated non-linear trends between crash energy and residual crush. The total body of available crash test data indicates that vehicle frontal stiffness cannot be precisely modeled through the use of single linear spring stiffness for all vehicles. This paper explores stiffness trends and makes comparisons to the previously assigned linear assumption for a diverse sample of vehicles and test speeds into frontal fixed barriers. The available crash test data is plotted and analyzed and the resulting linear and non-linear trends are discussed. Applications to the accident reconstruction