Boundary Element Inverse Analysis with Regularization for Estimating Welding Residual Stress Distribution in Butt-Welded Plate

概要

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This paper deals with an inverse problem for estimating welding residual stresses in a butt-welded plate from measured data. In previous papers, a method of thermo-elastic boundary element inverse analysis was proposed to estimate the inherent strains in the butt-welded plate. It was found in the papers that the accuracy of the evaluated inherent strain in the butt-welded plate was low when the location of the measurement points was far from the welding line or the number of measurement points was small. This paper examines how the shape of the inherent strain distribution affects the accuracy of the estimated results. Trapezoidal and triangular inherent strain distributions were assumed in each analysis model of the butt-welded plate. Numerical simulations were conducted for those analysis models. In the simulations, measurement errors were included in stresses at measurement points. From all calculation results, it was found that the inherent strains in the butt-welded plate were evaluated in high accuracy from a few measured data by using Tikhonov's regularization regardless of the shape of the inherent strain distribution. The residual stresses in the whole butt-welded plate were calculated from the evaluated inherent strains. Accordingly, it became clear that the proposed boundary element inverse analysis with Tikhonov's regularization was useful in evaluating the residual stresses in the butt-welded plate.