Strength analysis in piston crown of the marine diesel engine

This paper investigates the thermal strength, mechanical strength, coupled-field strength in the piston crown of MAN Diesel s 6S50MC-C marine engine. The changes of piston crown structure include increasing the depth of shaker cooling hole and blending edges in cooling oil chamber. The temperature fields, stress and deformation are calculated in different structure. Based on temperature field, thermal strength, mechanical strength and coupled strength are obtained in ANSYS. In original design structure of piston crown, the maximum stress is 694MPa under thermal load, 210MPa under mechanical load and 677MPa under coupled loads. The maximum deformation is 1.06mm under thermal load, 0.156mm under mechanical load and 1.08mm under coupled loads. The strength meets design requirement which the maximum stress is less than the material s yield strength. With increasing the depth of cooling holes, the maximum temperature, maximum thermal stress and maximum coupled stress are reduced. The results suggest that stress concentration is mainly caused by thermal load. Enhancing cooling and improving structural design are used to reduce destructive effect of thermal load.