Although extensive modeling efforts have been made in the past decades to predict occupant/pedestrian knee-thigh-hip (KTH) injuries, prediction for the injuries at the tissue level for various loading conditions observed in automotive crashes is still challenging. This study develops model-based tissue injury criteria and a tool to predict occupant KTH injuries subject to different postures and loading rates.

An effective plastic strain based injury criterion with a defined universal threshold was developed for identification of the potential injury locations in the KTH body region. The published cadaver KTH lowrate impact tests at three postures of neutral, adduction, and flexion by UMTRI (University of Michigan Transportation Research Institute) have been simulated with the Takata 50th% male human model. Using the defined criteria, the model predicted the hip-bone and hip-joint fractures for the three postures, were well correlated to those observed from the tests. The KTH impacts were also simulated at two loading rates. The simulation results indicated a possible mode shift of the impact rate-associated injury with assumptions of viscous effects on hip-joint. A high rate impact more likely generates a fracture at the femur shaft;​ and the impact at a lower rate more likely fractures the hip-joint.

The validated KTH injury criteria and tool were thus applied for accident reconstruction of two vehicle crash cases (full frontal and offset frontal impacts) selected from the NASS/CDS & CIREN database, which caused occupant KTH injuries at AIS 2-3 scale. The simulations match the injury outcomes of the reported field observations.