Structural optimization of a rubber bushing for automotive suspension

In this paper, the problem of the design of a rubber component for automotive application is discussed. The design of such components is complex due to the highly nonlinear response of the material and to the dif-ficulty in estimating its fatigue life. Many different material models can be found in the literature and employed for the description of the stress strain relationship. Referring to the static stress-strain characteristic, the designer has to choose among different models and to define the model parameters. Moreover, the fatigue life of the rubber is very difficult to be predicted and many different predictors and approaches have been proposed in the literature. The influence of different material models and of different life predictors on the design of a rubber component are investigated in the contribution. A simple case study related to the optimal design of a rubber bushing for the lower control arm of an automo-tive suspension system is presented. The design of the component is kept as simple as possible, thus, only the static stress/strain characteristic of the material is considered. A series of experimental tests is performed, both to characterize the material and to define the loading acting on the component. To objectively evaluate the influence of the different material models and life predictors, the design is performed by applying optimal design theory. The Pareto set, including the best design solutions is computed. By comparing the Pareto opti-mal sets, the effect of different material models and life predictors is discussed.