Buckle-Latch Insertion Force and Belt Tension in Everyday Driving

This study investigates the technique used and forces applied on the latch plate and buckle during typical seat belt operation and driving conditions. These techniques and forces are relevant to whether the latch plate can be partially engaged with the buckle during typical operation and whether the latch plate will dislodge during vehicle operation. In addition to studying the insertion of the latch plate, we examined the tensile forces that are applied to the latch plate and buckle during typical, non-crash driving conditions, and how these forces compare to the performance requirements established by the National Highway Traffic Safety Administration (NHTSA) as part of Federal Motor Vehicle Safety Standards (FMVSS) 209. These tensile forces are important in understanding whether the latch plate is likely to dislodge from the buckle if it is in a position of partial engagement. A study was conducted with 12 adult occupants of varying anthropometry and gender to evaluate seat belt buckle forces generated during typical seat belt operation and driving conditions. During this study, the force observed at the latch plate and buckle exceeded the 22-Newton partial engagement requirement by FMVSS 209.