Search Results

A modeling study was conducted to explore the potential for reducing rollover occupant injury via seat belt geometry modifications and the effect such modifications would have on frontal impact protection. MADYMO software was used to model the first roof-to-ground strike of a dolly rollover crash test as well as a frontal impact test using a facet-style human driver occupant in a sport utility vehicle. The objective of this study was to learn whether occupant protection could be improved for rollover without reducing occupant protection in frontal impact. The models were validated using crash test results. Seat belt anchor locations were independently varied in the models to examine the effects of shortening the length or increasing the angle of the lap belt, shortening the torso belt, or lowering the D-ring. Several combinations of the most promising independent anchor relocations were investigated first in near-side and far-side rollover and then in frontal impact.

The increasing prominence of end-release buckles in automotive restraint systems has been accompanied by criticisms that they are susceptible to inertial unlatching in collisions due to transfer of vertical impulses from the vehicle body or chassis through the buckle stalk to the buckle. It has been asserted that the accelerations imparted to the buckle are significantly amplified relative to the initial input to the vehicle body or chassis. In this study, a test procedure was developed to measure the in-situ dynamic response of restraint system buckles to vertical impulse. The procedure was used to evaluate buckle assembly response to impulses input at, or near, the buckle stalk floor anchors in several vehicles. The advantage of this technique over full-scale drop testing and component-level shock table impacts is that the desired response information may be acquired in-situ without damage to the vehicle.

Rollover crash and accident studies identify significant roof-to-ground impacts adjacent to the vehicle occupant as a potential cause of severe injuries. It is not possible with existing dynamic rollover test methods to specifically repeat or recreate a particular roof-to-ground impact in a controlled fashion. Variations associated with tire-to-dolly, tire/wheel-to-ground, and vehicle-to-ground interactions early in current rollover test methods tend to produce unpredictable and unrepeatable roof-to-ground impacts later in the test. A new test device now enables researchers to bypass the uncertainty of these first ground interactions by beginning each test with the desired roof-to-ground impact conditions as a test input. The new rollover test method releases a rotating vehicle onto the ground from the back of a moving semi-trailer.