Use of structural dynamic and fatigue sensitivity derivatives in an automotive design optimization

Direct accounting for durability rarely finds its way into multidisciplinary optimization. Though reduction of loads by some means can certainly have a beneficial influence on the fatigue performance of a structure, changes in load levels are not a direct measure of the influence of design changes on fatigue performance. In this paper, a previously described method for calculating design sensitivities of a fatigue performance index is used in a simple optimization of suspension damping and stiffness on a simple truck model. The dynamic loading is a conceptual representation of the industrial practice of road testing and simulation. Results demonstrate the feasibility of using a direct measure of fatigue performance in formal structural optimization.