Please choose your delivery country and your customer group
Failure not only occurs when components fracture or yield under stress; it is also characterized by components failing to perform a required action. One such mechanism involving automotive seat belt buckles is the phenomenon commonly referred to as inertial unlatching. Inertial forces and motions resulting from accelerations and decelerations accompanying real world collisions such as vehicle rollovers can trigger the unwanted release of certain side-release and end-release buckles, leading to occupant injury or death. This study demonstrates this failure mode of some commercially produced automotive end-release buckles, and presents laboratory testing correlating accelerations to unlatching. Case studies of forensic evidence of unwanted inertial unlatching in practice are given. It can be concluded that inertial unlatching of seat belt buckles is an industry recognized phenomenon. Inertial unlatching constitutes a failure of the buckle to perform its intended purpose. Certain buckles can fail as a result of vertical and lateral accelerations during collisions and rollovers. Inertial unlatching thresholds of buckles can be determined and demonstrated by scientific, repeatable laboratory testing. From instrumented vehicle testing accelerations on the buckle or in the vicinity of the buckle have demonstrated accelerations far in excess of the threshold required to release some buckles. Some buckles have such a low release threshold that inertial release can be demonstrated by striking the latched buckle with a shoe or against a hip.