Residual Stress Measurement of Multi-Layered Plate by Curvature Method

Abstract

The authors proposed a curvature method to measure the principal residual stresses in an isotropic multi-layered plate composed of several plate elements whose elastic moduli and Poisson's ratios were different from each other. The formula for single plate was able to be derived as a special case from their general formula for multi-layered plate. The thing to be noted about multi-layered plate is that the linear expansion coefficient of each element is different and so the temperature variation of test piece causes a change in the stress distribution. Therefore, the authors introduced a formula to compensate the temperature difference, and proposed a compensation coefficient curve related to the removed thickness z. As applications of their method, they measured the residual distribution in 3-layered electrodeposited calculated from the formula for single plate. It was found that the stresses produced by the electrodeposition of copper and nickel under these conditions were 1.4 and 24 kg/mm² in tension respectively.