枚举模糊随机主要失效模式的准则法

基于模糊不确定性向随机不确定性的等价转换和有限元分析计算，建立了以失效模式相对重要度为依据的广义主要失效模式枚举的工程准则法．该方法可以综合考虑材料参数、结构几何以及外载荷等基本变量的随机和模糊两种不确定性因素对失效模式相对重要度的影响，通过合理选择门槛值，可以在保证计算精度的基础上尽可能的减小计算工作量．以平尾转轴的模糊随机可靠性分析为算例，给出了门槛值的经验值，并说明了所建工程准则法的合理性．

A PRACTICAL CRITERION FOR ENUMERATION OF THE FUZZY-RANDOM SIGNIFICANT FAILURE MODES

Based on the equivalent transformation from fuzzy variables to random variables and the finite element method (FEM) calculation, a practical criterion, with the relative probability importance as a measure of the failure mode, is presented to enumerate the fuzzy-random significant failure modes for the fuzzy-random reliability analysis of complicatd structures. Not only randomness but also fuzziness in the basic variables are considered in the criterion. The mean values and the coefficients of variation in the basic random variables arc included in the relative probability importance of the failure mode, as well as the equivalent mean values and the equivalent coefficients of variation in the basic fuzzy variables. With a high precision, the criterion can greatly reduce the computation cost and the possibility of missing important failure modes. The fuzzy-random reliability analysis for the shaft structure of an airplane is made to illustrate the rationality of the present method.