随机载荷作用下的曲轴工作可靠性分析

考虑到试件在实际工作中载荷循环特征的分散性对其疲劳寿命的影响,建立了一种以应力幅值和应力均值为基本随机变量的二维应力-强度干涉模型.讨论了该模型建立的原理,给出了干涉模型的几何示意图以及极限状态方程.应用该模型对S195型柴油机曲轴的失效概率进行了蒙特卡罗求解,其结果与实际统计的失效概率吻合较好.根据多种情况下的模拟数据,分析了曲轴强度均值及变异系数对其工作可靠性的影响.

Reliability Analysis of Diesel Engine Crankshaft Serving in Stochastic Loads

The fatigue reliability of a severing component is strongly influenced by the load asymmetric factor, which should be treated as a random variable with disparity. In order to evaluate component's failure probability more precisely considering the disparity of the load asymmetric factor, a 2-D stress strength interference model was constructed. Principle, geometric schematic and the limit state equation of this model were presented. In this model, the mean, the amplitude of applied stress were the two basic stochastic quantities to make up the joint distribution density function. Based on this model, Monte-Carlo simulation was made for a kind of single-cylinder diesel engine crankshaft. In comparison with the statistical data of actual failure cases, the yielded results were satisfactory. With simulations on more conditions, discussion about the influence of crankshaft strength and its disparity on working reliability was also given.