３次元溶接残留応力の簡易測定法に関する研究 ｎＬｙ法および単純化Ｌｙ法の提案

Abstract

The authors developed the measuring theory of three dimensional residual stresses induced in a long welded joint based on the theory of inherent strain, and two methods, Ly method and Lz method, were presented. Although these methods enable us to obtain very accurate residual stress distributions, they require so many measurements and machinery cutting. In many practical cases, the distribution at a specific point is sufficient for special purposes.To this end, in this paper, the authors developed an approximate measuring method of three dimensional residual stresses along the thickness direction at a specific point, based on the Ly method.According to this method which is named nLy method, the object is cut into a specimen with the specified aspect ratio. As the result, the cross section of the new specimen is in the state of plane deformation and effective longitudinal inherent strains can be measured in a simple way. Then, three dimensional residual stresses can be estimated by two dimensional stress analysis in stead of three dimensional one, using the finite element method.Furthermore, a simple estimation method which is named simple .L, method is proposed, admitting inclusion of estimation errors by simplification. By this method, three dimensional residual stresses can be estimated only by performing simple manual calculation.