Dynamic response analysis of the THOR-LX dummy lower extremity.

Regarding THOR-50AM dummy lower extremities (hereafter referred to as "THOR" and "THOR-LX") developed as an assembly of lower extremities for next generation dummies in frontal impact test, a series of tests have been conducted as follows. HYGE sled tests with a toe-board simulating the impact upon intrusion into the vehicle compartment around the occupant feet, dummy dropping tests with two different postures; one is the upright posture with the knees set straight and another is the posture with the knees bent, in order to apply impact loads and to measure/evaluate the impact response characteristics. The main findings obtained through the above are as follows. 1. HYGE Sled Tests (1) In the same impact conditions, some differences are seen by the polarity and values of tibia moment between THOR-LX and Hybrid III-50 AM dummy lower extremities (hereafter referred to as "HyIII" and HyIII-LX"). (2) When the floor displacement rate and/or toe-board rotation angle are increased, the ankles of HyIII-LX are locked up by dorsiflexion which affects the values measured with the tibia load gauges, whereas such an effect is absent with THOR-LX. (3) The values measured with the tibia load gauges roughly correspond with the floor/toe-board motion for THOR-LX, but the values of HyIII-LX sometimes do not correspond with the toe-board motion. 2. Dummy Dropping Tests (1) Values of tibia axial force of THOR-LX are closer to those obtained with the volunteers (University of Heidelberg data), while those of HyIII-LX are greater. (2) Due to differences in tibia-knee and tibia-ankle fitting locations, the values of tibia moment of HyIII-LX with inclined tibia axis become greater than those of THOR-LX with practically vertical tibia axis. (3) Due to differences in structures of legs, ankles and feet, the pelvis acceleration peak timing with HyIII-LX is earlier than that of THOR-LX in each one of the dummy postures, and the interval from the pelvis acceleration peak timing to the tibia load peak timing is shorter with HyIII-LX.