Prediction of optimal inspection time for structural fatigue life

An optimal inspection time model for structural fatigue life based on stochastic finite element method (SFEM) and first order reliability method (FORM) was presented. The uncertainties such as material parameters and loads which affect the fatigue life of the structure were regarded as random variables. Taylor expansion stochastic finite element method (TSFEM) was introduced to simulate the material behavior of the fatigue life. Reliability analysis was made respectively for crack initiation life and crack propagation life. Take the crack initiation life as service life and the crack propagation life as inspection time, so the optimal inspection time can be easily obtained from the reliability function of the whole structure. The method was illustrated through application to a plate with a central hole under variable-amplitude loading. The results show this method is proved to be feasible and applicable in comparison with Monte-Carlo simulation.