Failure analysis and design improvements of steel piston for a high-power marine diesel engine

Abstract

In this study, the failure analysis and design improvements of a steel piston for a marine engine were performed. In order to assess the high-cycle fatigue performance of the steel piston, the high-cycle fatigue durability test was performed and the failure happened in steel piston. Therefore, the present analysis focuses on simulating durability test and assessing high-cycle fatigue strength of the steel piston. For this purpose, the high-cycle fatigue load spectrum of the steel piston was determined by numerical simulation method, the mean stress and stress amplitude of high-cycle fatigue cyclical loads were obtained by critical plane method. Then the fatigue assessment model was built to explore the failure cause of the piston. And a new scheme was designed by improving the local structure of the object. The research results showed that the excessive stress amplitude caused by the alternating gas pressure was the root cause of steel piston failure. The new scheme satisfied the fatigue strength assessment and passed the engine durability test successfully, so the design improvements were effective. The simulation method and fatigue strength assessment method in this work may provide an effective way for the design and service life of steel piston.