Finite Element Based Life Prediction of a New Free Piston Linear Generator Engine Mounting

This paper presents the finite element based fatigue life prediction of a new free piston linear generator engine mpunting. The objective of this paper is to assess the critical fatigue locations on the components due to loading conditions and also assess the damage tolerance design. This paper shows the effect of mean stress and the probabilistic nature of fatigue on the fatigue life. The finite element modelling and analysis have been performed using computer-aided design and finite element analysis software packages and the fatigue life prediction was carried out using commercial fatigue codes. Stress-life approach and strain-life approach are applied to predict the fatigue life of the free piston linear engine mounting. The result is a life contour, showing how long each area of a mounting will survive under defined loading conditions. The results are expected to show contour plots of fatigue life, and damage histogram at the worst or most damagign case. This paper shows the comparison between the stress-life approach and strain-life approach. From the results, it can be concluded that Morrow mean stress correction method has been found to give the most conservative results for strain-life method. SAE 1045-450-QT and SAE 1045-595-QT materials are considered in this study. It can be also seen that SAE 1045-595-QT material gave consistently higher life than SAE 1045-450-QT material for all loading conditions for both methods.