A new framework for fatigue life prediction under random loading conditions

A new framework for predicting the fatigue life under random loading conditions is proposed in this paper. The piecewise stochastic rainflow counting (PSRC) is proposed to transform the random loading spectrum to a series of block loadings in a piecewise manner. The block loading sequence effect is considered through a block sequence randomization. The random fatigue limit model is used and enhanced by the Dietman mean stress correction model to calculate the fatigue life for a constant loading considering the mean stress effect and fatigue limit. Both the linear and nonlinear damage accumulation rule ae used for the criterions for the fatigue damage accumulation until failure. The loading sequence effect for random loading is studied by comparing the results from the linear and nonlinear fatigue damage accumulation rule. The predicted fatigue lives are slightly conservative for the selected nonlinear damage accumulation rule than that for Miner rule in the proposed framework. The fatigue life prediction is better with the nonlinear damage accumulation rule.