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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.

When an automotive seat belt buckle is believed to have released during a motor vehicle accident, it is typically attributed to one of several potential mechanisms, including inertial release, partial engagement, inadvertent contact, or structural overload. While the majority of literature in the past has focused on the topic of inertial release, little has been written on other release mechanisms. This review paper addresses automotive seat belt buckle release by inadvertent contact between the buckle pushbutton and some other object. This paper describes the conditions that must be satisfied for inadvertent contact to result in buckle release, including release force, direction, and pushbutton travel. We explain the role of occupant kinematics and the likelihood of contact between and occupant's hand or arm and the pushbutton. Occurrences of inadvertent contact in safety testing and a real world case study are presented.