Coefficients of Restitution for Low and Moderate Speed Impacts with Non-Standard Impact Configurations

There have been a number of papers written about the dynamic effects of low speed front to rear impacts between motor vehicles during the last several years. This has been an important issue in the field of accident analysis and reconstruction because of the frequency with which the accidents occur and the costs of injuries allegedly associated with them. Several of these papers have discussed the importance of the coefficient of restitution in the accelerations and speed changes that the vehicles undergo in such impacts. These discussions often include data showing the measured restitution for impacts involving various bumper types and closing speeds. However, in most of these studies, the impacts are controlled so that direct bumper to bumper impacts occur.

This paper will present the results of several rear impact tests with non-standard impact configurations. These configurations include several passenger car bumper to light truck and SUV trailer hitch impacts, and partial underride impacts to vehicles with rear mounted spare tires. The results of these tests will be compared with the findings from several tests with more standard impact configurations, and the coefficients of restitution for each of the impact scenarios will be discussed.