Door Latch Integrity: Evaluation of Door Latch Failure Modes

Abstract The National Highway Traffic Safety Administration (NHTSA) is currently conducting research at the Vehicle Research and Test Center (VRTC) aimed at evaluating door latch integrity. Federal Motor Vehicle Safety Standard (FMVSS) 206 currently consists of a longitudinal tension test, a lateral tension test, and an inertial calculation. Several door latch failure mechanisms have been identified that are not properly evaluated by the current FMVSS 206 standard. Based on the results of an engineering analysis of door latch systems and a NASS case review, four types of failure modes have been identified: detent lever-fork bolt bypass, structural failure, linkage activation, and inertial unlatching. This paper presents the results of current NHTSA research and development aimed at determining the potential for the different failure modes stated above. The results of all the different types of testing conducted suggest that no single test procedure will determine the weak link in all types of latches. Several test procedures are required to fully evaluate door latch strength.