Simplified Measuring Methods of Three Dimensional Welding Residual Stresses : Proposal of nL_y Method and Simple L_y Method(Welding Mechanics, Strength & Design)

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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, L_y method and L_z 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 L_y method. According to this method which is nemed nL_y 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_y method is proposed, admitting inclusion of estimation errors by simplification. By this method, three dimensional stresses can be estimated only by performing simple manual calculation.
大阪大学の論文