The Numerical Analysis Of Welding Residual Stress Base On The Temperature And Stress Fields

As an important technology of steel structure, welding is a complicated processwhich involves in electromagnetism, heat transferring, metal melting and freezing andmechanics, which related to the quality of projects and the stability of structure.Because of high centralized instantaneous heat input, a great deal of residual stressand deformation should be brought in the process of the welding, which can heavilyinfluence the capability of welding structure. Therefore it is essential to calculate andanalyze the residual stress in welding structure. Based on others experience, withnumerical calculation, this paper researches how to realize the 3-Ddynamicsimulation of welding temperature and residual stress field, then uses the researchresults to simulate the welding process of the annular welding of hollow sphericaljoint. Furthermore, the calculation result accords with traditional analysis result andtheory result.The paper firstly describes the basic theories and numerical analysis methods ofthe temperature field and residual stress field. In the process of numerical simulatedcalculating, with the thermal-structure coupling function of Ansys software andindirect coupling, this paper deals with the single coupling whose temperature fieldeffects on stress and strain field and calculates the temperature field for the hollowspherical joint welding line. In order to improve the solution accuracy, it selectssuitable material properties, refines the girding, chooses the Gauss function movingheat source model and uses Ansys APDL language to compile program to applymoving heat source load in the process of numerical simulated calculating. Finallydynamic pictures of welding temperature field and temperature distribution curve ofeach point in welding line are shown.Based on accurate temperature field results, welding residual stress are alsocalculated by changing thermal elements into structural elements. By "Birth andDeath" method, elements whose temperature are in excess of material meltingpointsare 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 welding residual stresses and tendency of their distribution is presentedby post-solution.Through the research and practical verification, this paper establishes a feasibledynamic simulation method on 3-D welding temperature field and residual stress fieldof the annular welding of hollow spherical joint, providing the theoretic analysis ofresidual stress and instruction, promoting the application of FEM(Finite ElementMethod) on welding mechanics analysis and engineering.