Non-Linear Model Formulation for the Static and Dynamic Analyses of Front Suspensions

A three degree-of-freedom mathematical model formulation for a double-wishbone front suspension is presented which treats the effects of the tire vertical stiffness, the fore-and-aft bushing compliance in the lower arm, the compliance in a steering linkage and the inertia of the suspension links. The model equations are derived retaining all non-linearities associated with large changes in the geometric configuration of the suspension system and are solved within a digital computer program which computes the suspension force and displacement response to prescribed ground terrain inputs at the tire patch. Results obtained with the computer model are presented and compared with test measurements.