Abstract
Keywords:
Brinell Hardness, Fatigue, Local Strain, Residual Stress, Welded Structures
Abstract
Experimental study on the fatigue behavior of a material, SM490A was carried out on double V-grooved butt welded plates such as reinforcement removed, as-welded and weld toe ground. In addition, welded plates with transverse fillet welded web, load carrying cruciform fillet welded plates, non-load carrying cruciform fillet welded plate and longitudinal butt welded plates were tested. To simulate the observed fatigue behavior taking into account the residual stress relaxation, the modified Goodman diagram, notch effect and nominal stress, we propose a model to evaluate the fatigue lifetime of welded joints with residual stresses. In the model all fatigue parameters are replaced by the Brinell hardness. 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 stresses on the surface of the specimen decreased gradually and changed to compressive stresses as the applied loading was getting higher. Using the stress and strain obtained by the Ramberg-Osgood relation and the Lawrence formula we evaluated the fatigue lifetime of the welded joints from the S-N curve for the parent material. The estimated results are in a good agreement with the experimental results.