Abstract. Taking overlap joint as the object, it simulates welding process. And it obtains residual stress and distribution curves. By simulating the equivalent form of tack welding, it discusses the influence of tack welding by XYZ displacement constraint, X displacement constraint, node matching and adhesive contact on stress distribution. It verifies the results. The results show that four sets of tack welding are designed, and it calculates stress distributions. By XYZ displacement constraint, X displacement constraint and node matching, the simulation results is not consistent with the classical longitudinal stress distribution. By adhesive contact, the stress distribution is consistent with the test results, and error is controlled within 12.9%. It verifies the equivalent form of tack welding. Without considering tack welding, error is 40.3% at the distance from arc building of 50 mm. It does not meet the application requirements. It suggests that tack welding influence on the welding residual stress should be considered in the small model, and it simulates tack welding by adhesive contact.

Abstract. Taking the turntable of the crane as the object, it simulates the equivalent forms of process reinforcing in the large floor of the turntable. And it obtains welding deformation. By simulating the equivalent forms of process reinforcing, it discusses the influence on welding deformation by rigid fixed, contact, the unidirectional deformation constraint and adhesive contact. It verifies the results by experiments. The results show that they design four groups of the equivalent models, and calculate the welding deformation results of the large floor. When process reinforcing is equivalent to rigid fixed and contact, it predicts the deformation greatly. When process reinforcing is equivalent to the unidirectional deformation constraint and adhesive contact, it predicts deformation relatively small. By adhesive contact, deformation distribution is consistent with measured results, and error is within 6%. It verifies equivalent method is practical in the finite element analysis.