60g INERTIA LOAD ANALYSIS OF AUTOMOTIVE DOOR LATCHES

The FMVSS 206 (Federal Motor Vehicle Safety Standard 206) standard and the SAE J839 (Society of Automotive Engineers J839) recommended practice specify that an automotive door latch shall not disengage from the fully latched position when a longitudinal or transverse inertia load of 30 g (gravity) is applied to the door latching system. A further specification on the latch unit alone states that the latch shall not disengage from the primary latched or secondary latched position when placed in a half-bite condition and subjected to a 60 g inertial load applied in specific directions. These standards must be followed when designing a latching system; they are necessary requirements to ensure occupant safety. In this work, a 60 g inertia load analysis in a representative automotive door latch unit alone is presented. Hand calculations of the analysis will be compared with results obtained from a customized Unigraphics program. The analysis will show that the latch unit meets the specified requirements.