基于动力学的柴油机连杆疲劳仿真

为评估某大型柴油机连杆的疲劳特性,建立了模态缩减的动力学模型,获得连杆的循环载荷历程,结合以轴瓦高出度过盈的加载方法,模拟了整个工作循环的动态应力变化,随后基于多轴疲劳模型并采用两种等效方法,预测了连杆的疲劳危险位置。结果表明,该连杆的最小安全系数出现在杆身油孔处,满足疲劳要求。针对动态载荷历程,按历程的拐点和极值法真实高效的反映连杆动态疲劳,不仅能反映拉压为主的杆身及油孔的疲劳危险位置,还能体现纵向摆动对大小端孔的疲劳影响,安全系数误差在3%以内。

Fatigue Simulation of Diesel Engine Connecting Rod Based on Dynamics Analysis

To assess the fatigue properties of connecting rod for large diesel engine, the modal reduction dynamics model was established, and a complete cycle load history was obtained. Combined with the bearing bush interference method, the dynamics stress of the whole working circle was simulated. Based on multi-axial fatigue model, the fatigue risk position was predicted with two equivalent methods. The results show that the minimum fatigue safety factor of the connecting rod appears in the oil hole of rod body and satisfies the fatigue requirement. With regard to dynamics loading course, the method using the inflection point of the loading course and the extreme value can effectively simulate the actual dynamic fatigue of the connecting rod, including not only the fatigue risk position at the rod body and oil hole, but also the fatigue influence of longitudinal oscillation on the connecting rod eye at both ends, with the safety factor error within 3%.