Fatigue analysis of marine diesel engine crankshaft

Abstract

As one of the critical components of the main engine, the crankshaft must not be damaged during the whole operating life. Hence, fatigue characteristic analysis and life assessment plays an important role in crankshaft development. This paper analyses the fatigue strength of a marine diesel engine crankshaft and the influence of different fillet structures on the safety factor. First of all, in order to get the stress results and the stress load history of crankshaft fillet, this paper uses the finite element method to analyze the whole model and sub-model. Then, the occurrence time and position of the maximum stress in the running process is located by using the programming script. And the load spectrum is obtained by using the rain flow counting method. Finally, through the calculation, the state of maximum stress and fatigue strength are obtained. The minimum safety factor of the crankshaft fillet is 2.209, which is larger than the specified value. Therefore, the diesel engine has high reliability during operation. In order to solve the problem of stress concentration and machining at the fillet, the crankshaft fillets with different structures are also analyzed in this paper. Through the comparative analysis of the proposed scheme, the most suitable crankshaft fillet structure is two-way sinking groove fillet. So the application of this type of fillet should be considered in the design stage of diesel engine crankshaft.