Research On Residual Stress Of Welding Structure

As an important technology of steel structure, welding is a complicated process which involves in electromagnetism, heat transferring, metal melting and freezing and mechanics, which related to the quality of projects and the stability of structure. Because of high centralized instantaneous heat input, a great deal of residual stress and deformation should be brought in the process of the welding, which can heavily influence the capability of welding structure. Therefore it is essential to calculate and analyze the residual stress in welding structure. Based on others experience, with numerical calculation, this paper researches how to realize the 3-D dynamic simulation of welding temperature and residual stress field, then uses the research results to simulate the welding process of the T-section welding plane. Furthermore, the calculating results is in good accordance with the test results.The paper firstly describes the basic theories and numerical analysis methods of the temperature field and residual stress field. In the process of numerical simulated calculating, with the thermal-structure coupling function of Ansys software and indirect coupling, this paper deals with the single coupling whose temperature field effects on stress and strain field and calculates the temperature field for the T-section welding line. In order to improve the solution accuracy, it selects suitable material properties, refines the girding, chooses the Gauss function moving heat source model and uses Ansys APDL language to compile program to apply moving heat source load in the process of numerical simulated calculating. Finally dynamic pictures of welding temperature field and temperature distribution curve of each point in welding line are shown, as well as heat circulation in heat response areas and welding centre line is described by post-solution.Based on accurate temperature field results, welding residual stress are also calculated by changing thermal elements into structural elements. By "Birth and Death" method, elements whose temperature are in excess of material meltingpoints are killed and any other element not in excess of material melting points are activated. Therefore, dynamic simulation on metal melting and freezing is fulfilled. A curve of regularity on transverse and longitudinal welding residual stresses and tendency of their distribution is presented by post-solution.Through the research and practical verification, this paper establishes a feasible dynamic simulation method on 3-D welding temperature field and residual stress field of the T-section welding plane, providing the theoretic analysis of residual stress and instruction, promoting the application of FEM(Finite Element Method) on welding mechanics analysis and engineering.