考虑疲劳本构随机性的结构应力疲劳可靠性分析方法

STRUCTURAL STRESS-BASED FATIGUE RELIABILITY ANALYSIS CONSIDERING THE RANDOM CYCLIC CONSTITUTIONS

提出考虑疲劳本构关系随机性的结构应力疲劳可靠性分析方法。视循环本构模型的材料常数为相关随机变量,考虑存活概率和置信度2个概率测度,与疲劳试验有机结合,应用极大似然原理建立随机疲劳本构的概率模型。随机疲劳强度即概率S—N关系也用2个概率测度下表征,并考虑从中短到长寿命阶段的可能工程实践范围。基于载荷史服从疲劳本构关系产生随机应力载荷、给定寿命时概率S—N关系揭示结构强度分布的观点,建立随机应力载荷—强度干涉可靠性分析模型,可实现任意概率水平的可靠性寿命预测和可靠度评定。中国铁路货车RD_2型车轴的可靠性寿命预测和可靠性评定,说明了方法的有效性。

A structural fatigue reliability analysis method is presented to consider random cyclic constitutions. A characterization for the random constitutions is established by using two probabilistic measurements of survival probability and confidence. The entire material constants in the constitutive equation are reasonably taken as dependent random variables. The probabilistic S-N relations covering from mid-short life regime to long life regime, representing structural fatigue strength, are also given on the two probabilistic measrueraents. Considering that the random constitutions derive random stresses of structures under cyclic loading and the probabilistic S-N relations introduce random strengths of structures anti-fatigued cycling, reliability assessment is then constructed by considering interference of the random cyclic stress and strength. The method can be applied to realize fatigue reliability life prediction and reliability assessment at arbitrary probability level. Availability of the present method has been indicated by the reliability life prediction and reliability assessment of RD2 type axle of Chinese railway freight cars.