Abstract: Significant error of the measuring result may arise when measuring high residual stress by means of the centre hole method. And because the material around the hole is close to the yield limit, plastic deformation induced plastic strain. The strain release coefficients related with the angle between the principal direction of stress and the direction of the strain gauge, the biaxiality ratio, and the equivalent stress are studied . Then by FEM (Finite elcment method) the strain release coeffi-cients including plasticity effects are recalculated, which we used to measure and calculate the residual stresses induced by welding in welded Aluminum plate.

Key words: Centre hole method, FEM (Finite element method), Residual stress, Welding