多部位损伤结构概率疲劳寿命预测方法与模型

PROBABILISTIC FATIGUE LIFE PREDICTION APPROACH FOR MULTI-SITE DAMAGE COMPONENTS

结构疲劳失效是一种具有高度不确定性的现象,多部位损伤结构疲劳失效更是如此。含有多个薄弱环节(通常是可能发生损伤的高应力部位)的结构相当于多个只含有单一损伤部位的单元串联构成的系统。应用精确的系统可靠性建模方法,用各损伤部位疲劳寿命的次序统计量和极值统计量表示结构寿命分布,建立了多部位损伤结构的概率寿命预测模型。这样建立的模型自然地反映了不同损伤部位之间的失效相关性。试验结果及算例均显示,多部位损伤结构的疲劳寿命明显低于按其中一个损伤部位(即便是最薄弱部位)计算的寿命。

Fatigue is a phenomenon of high uncertainty, especially for components with multiple damage sites. The fatigue life （ either mean value or probability distribution of the random variable） of a complex component with multiple damage sites is not equal to that of a simple component with only one damage site. A multi-site damage component is a series system with many weak links （damage sites） in probability sense. A probabilistic fatigue life prediction model for multi-site damage component is presented based on a systematic thought, as well as the order statistics and extreme statistics concept. Such developed model can naturally reflect the effect of the dependence among different damage sites. Experimental result and the example on multi-site damage component fatigue life prediction shows that the fatigue life of a multi-site damage component is much lower than that of a single site damage component.