A Generalized Random Variable Approach for Strain-Based Fatigue Reliability Analysis

Abstract

A new reliability technique for strain-based fatigue life design is developed in this paper. An empirical mean stress modified strain-life equation is used as performance function, in which: material property parameters, as fatigue strength coefficient and fatigue ductility coefficient; and mean stress and applied strain are taken as random variables. A major feature of this work is that, in the performance function, the terms involving material property parameters are combined into one generalized random variable as “capacity,” and the terms involving mean stress and applied strain are combined into another generalized random variable as “demand.” The limit state is then analyzed by using the interference technique to evaluate the reliability under a specified life. Another significant feature is that in order to meet the need of fatigue life design application, for a given cyclic strain history, a numerical method is developed to inversely search the life when certain reliability is specified. Two numerical cases are presented to demonstrate the method. [S0094-9930(00)01202-6]