Predicting fatigue crack propagation in residual stress field due to welding by meshless local Petrov-Galerkin method

This paper introduces a novel procedure to develop the MLPG method for investigating residual stress effect on the Fatigue Crack Propagation (FCP) rate. A new formulation is introduced based on thermoelastic-plastic equation for this method to numerical analysis of the residual stress due to welding. The most important part of numerical analysis by MLPG method is to determine the residual stress redistribution due to crack growth and calculation of the Stress Intensity Factor (SIF) in residual stress field. A good agreement is seen between the outputs of MLPG method to the Hole-Drilling Strain-Gage method results. The standard weight function is developed without increasing the computational time for simulation of the displacement and stress around the crack. The Superposition principle is employed to consider the residual stress effect on the SIF and cycle ratio. Finally, the Walker's FCP equation is modified to take into account the simultaneous effects of cyclic loading and residual stress. It was discovered that the results obtained from the purposed method is in a good agreement with FCP experimental results. Therefore, it can be concluded a new approach is developed to analyze the calculation of SIF in the residual stress field and its effect on the FCP rate.