Numerical Simulation of Vibrations for the Design of a Rear Axle

The construction and design of the axles of a new vehicle is one of the most important parts in developing a car. Lightweight structures are used in order to reduce the weight of cars. This can be reached using new materials that are often more flexible, e.g., using aluminium instead of steel. So the conventional rigid multibody models seem to be no more sufficient for the accurate modeling of all physical properties, in particular the vibrations. Therefore, we investigate a multibody model of a rear axle, which contains an elastic subframe. In order to reduce the degrees of freedom of the finite element model, the dynamic behavior is approximated by the modal Ritz ansatz. This approach is a good approximation of the deformation of the subframe, because the deformations are small. In the software package ADAMS that can be used for solving multibody systems the Craig-Bampton method is used for this approach. We focus our investigations on the lateral vibrations of the rear axle. Numerical results for a rigid and an elastic multibody formulation are presented and discussed.