疲劳可靠度分析的概率密度演化方法

Fatigue Reliability Analysis Based on Probability Density Evolution Method

基于概率守恒原理,推导出疲劳损伤和随机参数联合概率密度函数服从的演化方程。据此计算的随机疲劳损伤概率密度曲面和累积概率分布函数等值线可以给出疲劳损伤概率结构的演化规律,并用以分析给定损伤阈值的疲劳可靠度。常幅疲劳可靠度的数值解与试验结果吻合良好。给定二级载荷各自的常幅疲劳寿命概率分布参数,根据Miner准则可以较好地预测二级低高加载变幅疲劳可靠度。

Based on the probability conservation principle, a joint probability density evolution equation of random parameters and fatigue damage is derived. Probability density evolution surface and cumulative probability isoline of fatigue damage in term of the evolution equation can be used to predict the probability distribution of fatigue damage and fatigue reliability with a given damage threshold. The numerical solution of fatigue reliability for a constant-amplitude test has a good agreement with the experimental result. For a variable-amplitude fatigue test, the computation results, which are calculated according to probability parameters of two constant-amplitude fatigue life tests and Miner＇s rule, are also in good agreement with the experimental results.