Study of Vehicle Dynamics and Occupant Response in Side Impact Crash Tests

Side impact crash is a leading cause of fatalities on the roadways of the industrialized world. In the mid 1990's NHTSA implemented a new car assessment program testing the lateral crashworthiness of vehicles entering the market with a moving deformable barrier. Previous work has been done in an attempt to distill these tests into finite element simulations using specific vehicle test results; however there has not been a comprehensive study attempting to develop a model that includes a large number of tests to evaluate trends in vehicle kinematics and how they affect the occupants coupled with finite element simulations. To this end, a study of side NCAP tests was performed on all sedans based on the test results reported in the NHTSA Vehicle Crash Test Database since the introduction of the 2005 model year. This data was used to evaluate typical motion of the target vehicle during a regulatory crash test, and the corresponding occupant response. This sample consisted of new models entering the market and nameplates with major redesigns with a sample size of 72 vehicles. From these tests a series of velocity profiles were developed including time versus average velocity plots for vehicle center of gravity, door sill, driver’s seat and driver door. These parameters have been shown to be important in occupant response and injury. There was significant variability in the response at several accelerometer locations. It was also found that rotation of the vehicle did not become significant until after 100 ms, after the maximum injury was predicted by the dummy. A parametric finite element analysis was performed using the both the USSID and ES-2re models to study the response of a restrained occupant during a typical crash test. These simulations showed that the velocity of the intruding door had a large effect on the thoracic injury predicted by the side impact dummy models.