A Generalized Two-Dimensional Model to Reconstruct the Impact Phase in Automobile Collisions A Generalized Two-Dimensional Model to Reconstruct the Impact Phase in Automobile Collisions
Vehicle collision analysis techniques generally separate the collision into three phases: pre-impact, impact, and post impact. The intent of the research is to provide a generalized model to reconstruct two dimensional impact problems in the area of accident reconstruction. There are currently two modeling techniques used to reconstruct the impact phase: the first technique relying exclusively on impulse-momentum theory coupled with friction and restitution, while the second method combines impulse momentum with a relationship between crush geometry and energy loss. Because each method requires very different inputs, the literature would have us believe that both methods are different. We will show that both methods are derived using the same fundamental physical principles and for any given accident scenario, both methods will provide identical results. Each method will be presented in the form of a MathCAD spread sheet that will allow the user to reconstruct a wide variety of accidents controlling just a few parameters (i.e. mass, rotational inertia, angle of approach, etc…). Both methods will provide step by step graphical representation to assure a solid approach to physical fundamentals. The governing equations to the generalized energy approach will be non-dimensionalized and used to define all of the changes in energy (i.e. also referred to as an impulse in power) as a function of a characteristic velocity. Finally, different methods to consistently determine the direction of the force will be presented when additional information from the accident scene is provided.
School:Brigham Young University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:vehicle collision impulse momentum generalized energy approach
Date of Publication:12/14/2006