A generalized random variable approach for strain-based fatigue reliability analysis

A new reliability technique for strain-based fatigue life design is develop ed in this paper. An empirical mean stress modified strain-life equation is used a performance function, in which: material property parameters, as fa tigue strength coefficient and fatigue ductility coefficient; and mean stre ss and applied strain are taken as random variables. A major feature of thi s work is that, in the performance function, the terms involving material p roperty parameters are combined into one generalized random variable as "ca pacity," and the terms involving mean stress and applied strain are combine d into another generalized random variable as "demand". The limit state is then analyzed by using the interference technique to evaluate the reliabili ty 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 dem onstrate the method. [S0094-9930(00)01202-6].