An Analysis of Upper Body Twisting Behavior in Frontal and Oblique Impacts using Hybrid III and THOR-FT Dummies

An analysis of real-world traffic accidents shows that vehicle-to-vehicle collisions at an oblique impact angle account for 80% of all frontal accidents. It is thought that twisting of the upper body and legs of occupants occurs in this type of accident because of rotation of the vehicles at the time of impact. Such twisting of an occupant's restrained upper body might affect the effectiveness of occupant restraint systems, for example, an airbag may strike the head or thorax area at an oblique angle.

The mechanism of upper body twisting and the possible effect of such twisting behavior on the performance of restraint systems were analyzed. Frontal sled tests were conducted to compare the response of the Hybrid III dummy and that of the next-generation THOR-FT dummy featuring improved biofidelity. MADYMO simulation models of the Hybrid III dummy and the THOR Alpha dummy were also used to examine occupant behavior in frontal impacts. It was found that the THOR-FT dummy exhibited greater upper body twisting than the Hybrid III dummy, which is attributed to the increased flexibility of the former dummy's thoracic spine. Owing to the different behavior displayed by the THOR-FT dummy, it was seen that the dummy's right arm came in contact with the steering wheel rim in a frontal impact and that the shoulder belt tended to slip off the dummy's shoulder in an oblique impact. The interaction of the dummy with the restraint system tended to differ from that seen for the Hybrid III dummy.