Fatigue life evaluation model for welded joints with residual stresses

We proposed a model to evaluate fatigue lives of welded joints with residual stresses. After analyzing the welding process by finite element method, we conducted elastic-plastic finite element analysis to quantify the degree of residual stress relaxation due to applied loadings. Maximum tensile residual stress on the surface of the specimen decreased gradually and changed to compressive stress as the applied loading was larger than a value. Using the developed model we evaluated the fatigue lives of four kinds of welded joints from the S-N curve for the parent material. The estimated results are in a good agreement with the experimental results.