PREDICTION OF DISTORTION PRODUCED IN WELDED STRUCTURES DURING STRAIGHTENING PROCESS USING THE INHERENT STRAIN METHOD

摘要

In order to optimize the straightening process, it is necessary to predict the deformation due to local heating. Numerical simulation is an advantageous way to do this. In this study, Osaka University's inherent strain based welding simulation code JWRIAN is modified so that inherent strain's equivalent nodal forces are calculated in cases where the inherent strain confines within narrow region whose size is smaller than element size. In the developed code, the initial strain force vector and element stiffness matrix's non-linear term which includes stress components are integrated using higher order (e.g. 20 × 20 × 6 for 4-nodes shell elements) Gauss-Legendre quadrature while other quantities are evaluated by using ordinary order (2 × 2 × 2) quadrature. The validity of the developed software is examined by comparing rectangular plate's angular distortion due to gas line heating calculated by three-dimensional thermal-elastic-plastic analysis and that calculated by the developed system.