On Body Mount Crash Characteristics

This paper reports a study of the impact dynamic characteristics of body mounts in a body-on-frame vehicle. Two methods of dynamic analyses are utilized. One method is direct impact; and the other excitation on the body mount. Using a series of component test data, the direct impact method yields the natural frequency, f, and damping factor, ζ, for a spring-mass-damper model of a body mount. The functional relationship between the g-force versus deflection curve and f, ζ, and v (impact speed) is examined. Given a frame impulse, the excitation method predicts the body response by the convolution integral. The transient transmissibility (TT), the ability of a body mount to transmit shock impulse from the frame to the body in the early part of crash duration, is investigated. The degree of front-loadedness on the body pulse is determined by TT and thus it affects the occupant/vehicle crash response.