Abstract
The thermal elastic-plastic analysis for the welding transient and residual stresses and deformations needs the huge computation time to obtain the accurate results. In this study, a new method, a step iterative total strain method, was developed to shorten the computation time largely, keeping high accuracy. The theory can take account of not only the temperature-dependencies of the mechanical properties, as usual thermal elastic-plastic theory, but also the change from elastic state to elastic-plastic state in one large temperature increment. Based on the theory (the thermal elastic-plastic constitutive equation), the equilibrium equation (the stiffness equation) was developed in the finite element method (FEM). New FEM program for thermal elastic-plastic analysis was developed, based on the above theory. A simple important problem of thermal elastic-plastic behavior was analyzed to verify the capability (accuracy) of the new method. In the next report, complex typical welding problems will be analyzed. As a result, it will be confirmed that the computation time is very largely shortened, compared with the usual incremental method, keeping the high accuracy.
