2006 Issue

www.utahengineerscouncil.org 23 UECJOURNAL February 2006 phase of a crash. In the rollover phase, it is usu- ally not practical to try to determine the energy dissipated in each and every vehicle-ground interaction, rather the speed of the vehicle at the trip point and throughout the rollover is reasonably estimated based on the distance from the vehicle to the final rest position and an average deceleration rate to calculate a total energy loss from rolling along this distance. One measure of rollover accident severity is the to- tal number of vehicle rolls; however full-scale crash tests show that there is no linear correla- tion between the total roll distance and the number of vehicle rolls. Thus, the traditional and best method of analysis of the rollover phase begins with matching all available physical evidence between vehicle and scene in completeness and in the proper order. This allows several known vehicle positions and orientations to be established along the path of the roll; the remaining vehicle positions are simply determined consistent with scientific laws of nature. The tradi- tional method provides a solid basis for the determination of detailed rollover dy- namics (including translational and rota- tional velocity, damage sequence and number of rolls), as well as evaluation of occupant kinematics, vehicle and compo- nent performance, opportunity for occu- pant injury and even occupant ejection. Evaluation in a piecewise (phase-by- phase) fashion is a very good approach for the determination of vehicle dynamics in an automobile rollover crash. ■ Seat Belt Safety F E A T U R E AMERICAN SOCIETY OF MECHANICAL ENGINEERS www.asme.org Cha i r Steve Maughn FMC Technologies Vice Chair/College Relations Norm Smith Web/Newsletter Editor Jon Bready UEC Representative David B. Merrill Van Boerum & Frank Contact Information: Steve Maughn Phone: 801-629-3447 E-mail: steven.maughn@fmcti.com Evaluation in a piecewise (phase-by-phase) fashion is a very good approach for the determination of vehicle dynamics in an automobile rollover crash. The pre-rollover phase includes the first events that lead to the vehicle overturning