Prediction of Stiffness Coefficients for Frontal Impacts in Passenger Vehicles 2014-01-0468

Vehicle stiffness data are often used in crush energy analyses, in conjunction with conservation of momentum calculations, to compute vehicle speeds at impact for accident reconstruction purposes. The vehicle stiffness data are typically obtained from standardized impact tests, such as from the New Car Assessment Program (NCAP) or from Federal Motor Vehicle Safety Standard (FMVSS) tests. Ideally, these data are most applicable when obtained from a sister or clone subjected to an impact similar to the accident. However, when vehicle-specific data are not available, a common alternative is to use crush stiffness values for a generic vehicle population from the published literature. These publications are limited in number and, depending on the user's requirements, may have some inherent limitations. For example, use of the generic values may not readily apply to a recently manufactured subject vehicle involved in a side or rear-end impact. Of the currently published studies providing generic class stiffness data, one publication covers vehicles manufactured in the 1980's and 1990's, while another covers frontal impacts over 3 decades. It is expected that recently manufactured automobiles will have different stiffness values from their previously manufactured counterparts, given the advancements in manufacturing and production technology, and utilization of different structural materials. The current study investigates the variation in crush stiffness values as a function of wheelbase, as reported in previous studies, and as a function of other parameters such as vehicle weights, front overhangs, and overall lengths.