多级载荷累积损伤下结构的动态可靠性分析

摘要

在服役环境中的各种不确定性因素及时间因素的共同作用下,结构将产生强度退化与累积损伤,进而严重影响到可靠性.传统的可靠性模型不能很好地反映载荷作用次序与强度退化等因素对可靠性的影响.利用区间理论,考虑应力作用次序不同而导致疲劳损伤的不同非线性演化过程,研究了多级载荷的等效转化问题;为承受多级载荷的强度退化下的结构,建立了动态非概率可靠性预测模型,构造了一种区间模型的动态可靠性分析方法;通过算例对多级载荷累积损伤作用下的结构动态可靠性进行了分析,并验证了方法与模型的有效性.%Under the functions together with various kinds of uncertainty factors and time factors in the service environments,strength degradation and cumulative damages on structures would be conducted,and thereby seriously affected the structural reliability.The traditional reliability model could not reflect the influences of loading sequence and strength degradation.The problems of the multi loads equivalent transformation were studied herein by using interval theory and considering nonlinear evolution phenomena of fatigue damages caused by the different loading sequences.Aiming at the strength degradation structures under the multi-level loads,the dynamic non-probabilistic relia-bility prediction model was established and the analytical method of time-dependent reliability was constructed based on an interval model.Finally,by calculating an example,the time-dependent relia-bility for structures under multi-level loads was analyzed,and the validities of the method and model were verified.