基于泛灰数的结构疲劳寿命区间估计方法

摘要

针对利用区间算法求解含有不确定性参数结构的疲劳寿命值精度低问题,提出一种泛灰求解方法.泛灰数运算不仅可以有效处理结构不确定参数,且能解决区间运算扩张问题.首先将不确定性设计变量用区间数来表征,不考虑变量的具体分布情况;其次利用泛灰数特性,将区间变量转化为泛灰数,利用等效泛灰数计算结构疲劳寿命上下界;最后通过两个数值算例,求得的结构疲劳寿命范围比传统区间算法得到的范围更小,且与改进的截断法的结果相近,同时还利用Monte Carlo方法验证了方法的有效性.泛灰方法利用较少的信息量得到较精确的疲劳寿命估计结果,一定程度上解决了工程实际结构参数疲劳寿命估计过于保守问题,节约了设计成本.%Estimation of the structural fatigue life with uncertain parameters is usually of low precision when using interval parameters.Thus,a new method employing universal grey numbers to tackle the problem is proposed.First,uncertain design variables are represented as intervals without considering their specific distribution.Using universal grey number characters,we transform intervals into the equivalent universal grey numbers,and calculate the upper and lower bounds of the structural fatigue life.Two numerical examples indicate that the range of the structural fatigue life obtained by using the proposed method is narrower than those obtained by traditional interval methods.Moreover,they are almost the same to the results by using the advanced intercept method.Meanwhile,the Monte Carlo method is applied to verify the results of the proposed method.The proposed method can acquire a more precise result of fatigue life with less information.Furthermore,to some extent,it solves the problem that fatigue life parameter estimation of actual engineering structure is usually too conservative.Thus,using our method to calculate the fatigue life of the engineering structure can save the design cost.