Equivalence of impact phase models in two vehicle planar collisions
Determining the pre-impact velocities of vehicles are of prime importance when investigating road traffic collisions. Two types of impact-phase model are in common use to achieve this purpose, those based on the conservation of linear and angular momentum as exemplified by the models presented by Brach and Ishikawa and the CRASH model which explicitly includes the conservation of energy. A summary of the various models is provided to show how the models are related to each other together with a brief discussion of their strengths and weaknesses. Of particular significance is that although there are differences between these models it is shown that they are equivalent provided certain conditions are satisfied, namely that the crush or impact plane is orientated perpendicular to the impulse. In addition it is shown that they produce identical results from consistent input data. Explicit conversion factors between the models are provided together with a novel method to transform coefficients of restitution between various orientations of the crush plane. This facilitates comparison and movement between the models and it is shown that the choice of model utilised for an individual collision depends largely on the availability of particular data.
Citation : Neades, J. (2013) Equivalence of impact phase models in two vehicle planar collisions. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 227 (9), pp. 1325-1336
Peer Reviewed : Yes