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Impact induced vehicle residual deformation serves as a basis for the reconstruction engineer to make a determination of the energy absorbed during the impact phase of a collision. Many impact phase reconstruction algorithms assume a linear 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 a single linear spring stiffness for all vehicles. This paper will explore stiffness trends and make comparisons to the previously assigned linear assumption for a diverse sample of vehicles and test speeds into frontal fixed barriers.

This paper surveys some current technologies in reconstructing lateral narrow object impacts. This is accomplished through a multi-step process. First, staged crash test data is reviewed and presented in order to understand the observable vehicle structural deformation trends. A commonly used crush energy reconstruction algorithm (CRASH1) is then applied to the test data and an analysis is made of the application of this tool to this impact mode. The use of default structural parameters as used in CRASH 3 is also discussed. A linear and angular momentum analysis is developed in order to demonstrate closed form vehicle dynamics prediction methodologies for non-central lateral impacts. The momentum methods presented are compared to a commonly used impact simulation tool. Finally, change in velocity (ΔV) and the use and analysis of ΔV for lateral pole impact reconstruction is discussed.