Lower extremity response of the Thor-LX compared to the Hybrid-III lower leg in frontal barrier crash tests

The Thor-Lx leg and foot complex is being developed by the National Highway Traffic Safety Administration (NHTSA), the Applied Safety Technologies Corporation, and GESAC, Inc., as a new research and development (R&D) tool which will be more biofidelic than the current Hybrid-III lower extremity. This paper reviews the results from a matrix of tests performed to evaluate the response of the Thor-Lx in comparison to the Hybrid-III lower extremity in high-speed frontal crashes. The testing included three 64 km/h frontal offset deformable barrier tests and two 56 km/h flat rigid barrier tests. Testing was done using the following Anthropomorphic Test Device (ATD) combinations: Hybrid-III with the Hybrid-III Enhanced Instrumented Tibia, Hybrid-III with the Thor-Lx, and Thor with the Thor-Lx.

The response of the lower extremity was found to vary with each leg and torso combination. Tibia bending moments were reduced and the lower tibia axial compressive force was increased in the Thor-Lx when compared to the Hybrid-III tibia. This phenomenon is attributed to the Achilles' tendon added to the Thor-Lx. When the Thor torso was used, loads measured in the lower extremity were lower than when the Hybrid-III torso was used. This lower level of loading is a result of changes in the torso kinematics that reduce the forward stroke of the pelvis.