基于高周疲劳分析的船用柴油机活塞结构优化设计

Optimized Design of Marine Diesel Engine Piston Structure Based on High Cycle Fatigue Analysis

针对某船用柴油机活塞的温度场和热机耦合应力场进行分析,并基于高周疲劳分析理论评估其疲劳强度。仿真结果显示,危险部位位于内腔上侧圆角过渡处和活塞顶面中心区域,应力幅值过大是导致安全系数较低的原因。针对此问题,进行结构改进,包括活塞支撑筋位置调整、销孔顶部支撑结构厚度增加和内腔上侧圆角过渡处调整,同时调整泄油道结构以改善冷却效果。结果表明,将活塞支撑筋移至销座1/2处、增加销孔顶部支撑结构厚度及调整内腔顶面圆角过渡处,有效提升了活塞顶面承载能力,降低应力幅值,显著提升安全系数。改进后的活塞满足设计要求,为未来船用柴油机活塞结构设计提供了参考依据。

The temperature field and thermo-mechanical coupled stress field of the piston of a marine diesel engine were analyzed,and its fatigue strength was evaluated based on the theory of high week fatigue analysis.The simulation results show that the dangerous parts are located at the rounded transition of the upper side of the inner cavity and the center area of the piston top surface,and the excessive stress amplitude is the reason for low safety factor.To address this problem,structural improvements were made,including the adjustment of the position of the piston support rib,the increase of the thickness of the support structure at the top of the pin hole,and the adjustment of the rounded transition at the upper side of the inner chamber.The oil drain structure was also adjusted to improve the cooling effect.The results show that moving the piston support bar to 1/2 of the pin seat,increasing the thickness of the support structure at the top of the pin hole,and rounding the transition at the top side of the inner cavity effectively improve the bearing capacity of the piston's top surface,reduce the stress amplitude,and significantly improve the safety factor.The improved piston meets the design requirements and provides a reference basis for the future design of marine diesel engine piston structure.