A nonlinear viscoelastic bushing element in multibody dynamics

This paper presents a formulation for incorporating nonlinear viscoelastic bushing elements into multibody systems. The formulation is based on the assumption that the relaxation function can be expressed as a sum of functions which are nonlinear in deformation and exponentially decreasing in time. These forces can represent elastomeric mounts or bushings in automotive suspension systems. The numerical implementation of the nonlinear viscoelastic bushing model into a general purpose rigid multibody dynamics code is described, and an extension of the formulation is also presented wherein component flexibility is included. Model validation was performed by comparing experimental data to simulation results obtained using the nonlinear viscoelastic model and a nonlinear elastic model. The experimental data were obtained at the Center's facilities by testing an automotive lower control arm/bushing system, subjected to a simulated road load event. The comparison demonstrates the better load prediction capability of the viscoelastic bushing model compared to the conventional model.