Fatigue life prediction of high temperature components in combustion engines and exhaust systems

The aim of the work described in this paper is to provide a computational method for fatigue life prediction of high temperature components in combustion engines and exhaust systems. The method allows a substantial reduction of the number of bench tests. The fatigue life prediction is based on a law for microcrack growth, which is the predominant damage mechanism under the thermo-mechanical loading conditions of these components. In addition, a powerful model for nonisothermal cyclic plasticity is employed, and an efficient laboratory test procedure is proposed for the determination of the model parameters. The models are efficiently implemented into finite element programs and are used to predict the fatigue life of a cast iron exhaust manifold and a sheet metal exhaust manifold. The simu lated fatigue lives correspond very well to results of component tests where cracks are found at the predicted locations.