Novel nonlinear time-varying fatigue reliability analysis based on the probability density evolution method

摘要

The evolution of fatigue damage in materials of structures under cyclic loading is a time-varying cumulative process. Method on time-varying fatigue reliability analysis is scarce due to the popular use of Miner's rule in defining the fatigue damage which does not consider the influence of the load sequence. A novel nonlinear time-varying fatigue reliability analysis method is presented to improve the accuracy and efficiency of time-varying reliability analysis. A nonlinear fatigue damage index is defined based on the toughness exhaustion of material, and the fatigue damage limit state function is then derived. This state function is then analyzed with the probability density evolution method (PDEM), and the generalized density evolution equation is solved numerically. The complete process of the time-varying fatigue reliability analysis is presented. Two sets of experimental results are employed to validate the proposed method. Results show that the accuracy and efficiency of time-varying fatigue reliability can be improved with the proposed method considering the effects of nonlinearity of the fatigue damage and loading sequence.