The Influence of Suspension Geometry on the Coupling of Lateral Acceleration and Ride Dynamics

The paper discusses the coupling of lateral and vertical vehicle dynamics, specifically, the effect of quasi-static lateral tire forces on vertical bounce dynamics. The effect is captured through the tangent stiffness matrix in a multibody dynamics formulation. Tangent stiffness is a property of a mechanism where the effective stiffness is influenced through internal preload. A multibody quarter-car model is explored under varying loading conditions, suspension geometries, and topologies. The model predicts that the coupling effect is significant, in some cases affecting the bounce frequency by up to 25%. The strength of the effect depends on the suspension geometry. While the location of the roll centre has long been recognized as the primary coupling mechanism between lateral and vertical vehicle dynamics (at least in the context of the suspension design), that is not the case with the demonstrated coupling effect. An alternate relevant geometric property is identified.