Search Results

The mechanism of whiplash is not well understood and thus preventing a certain motion or force in an occupant might not mitigate this injury. However, a number of injury criteria have been proposed to evaluate the neck injury risk in a rear-end crash. In the safety design of the seat and the headrest assembly, robustness or invariability of whiplash protection must be secured not only under the assessment pulses applied in sled tests but also under such pulses that show random multiple peaks in real-world car-to-car rear-end crashes. The aim of this study is to investigate a method of evaluating the invariability of whiplash protection performance in low-speed rear-end crashes, not with multiple injury criteria but with a single newly proposed objective function. The function was determined based on the hypothesis that the ideal seat is rigid in terms of such invariability.

A finite element human model has been developed to simulate occupant behavior and to estimate injuries in real-world car crashes. The model represents an average adult male of the US population in a driving posture. Physical geometry, mechanical characteristics and joint structures were replicated as precise as possible. The total number of nodes and materials is around 67,000 and 1,000 respectively. Each part of the model was not only validated against human test data in the literature but also for realistic loading conditions. Additional tests were newly conducted to reproduce realistic loading to human subjects. A data set obtained in human volunteer tests was used for validating the neck part. The head-neck kinematics and responses in low-speed rear impacts were compared between the measured and calculated results. The validity of the lower extremity part was examined by comparing the tibia force in a foot impact between the test data and simulation results.