Nondestructive Evaluation Method of Welding Residual Stresses by Heating Method

Abstract

In this paper, a new method of estimating welding residual stresses nondestructively is presented. From the strain changes on the surface due to the local change of Young modulus, distributions of eigenstrain are determined by the inverse analysis. Residual stresses are then evaluated by the elastic FEM analysis by using the eigenstrain as initial condition. Since the local change of Young modulus are due to temperature dependency by heating, we refered to the method as heating method. The method is used to estimate the residual stress distribution in a plate formed by joining two sections with a butt weld. The results show that the proposed method is robust, efficient and accurate. In this procedure, the simulated measured strains are generated by adding random error to the strain response form the solution of the direct solution, and the singular value decomposition method is used as a regularization method. The effects of number of sensors and their locations, the magnitude of measurement errors on the accuracy of estimations are investigated.