Functional analysis of bushing in four-link suspension on k&c characteristics using multibody dynamics method

The link of multilink suspension usually has bushings at both body connection and wheel carrier connection. These bushings are designed subjected to the function of link. In the studies of vehicle dynamics, bushing could be represented by three translational stiffness and three torsional stiffness as well as corresponding damping. Due to specific location and orientation of each bushing, usually only one of these six stiffness plays an important role. In this paper, effect of bushing on suspension K&C characteristics was investigated with a four-link suspension. Through virtual loading tests, force distribution of suspension bushing was studied to find the relation between bushing stiffness and K&C characteristics. In order to quantitatively measure effect of bushing stiffness on parasitic rate, an "equivalent force" method based on energy conservation was proposed. Similarly, an "equivalent displacement" method was proposed to measure effect of bushing stiffness on suspension compliance. According to theoretical analysis and numerical calculation result, six stiffness of a bushing could be classified into three categories: main function stiffness closely related to suspension behavior, sub-function stiffness affecting parasitic rate or subjected to large load and non-function stiffness to be controlled within an acceptable range.