Numerical Simulation Of Welding Residual Stress Of T-Tubular Joints In Steel Arch Bridge Supported By National Natural Science Foundation Of China (51378430)

Because of the high rigidity, light weight, easy construction, and good seismic performance, etc. steel structure has been widely used and rapidly developed over the past century. For the structure simplicity, good anti-fatigue performance and impact resistance, steel tubular structures have also become widely used by structural engineers With steel tubular structures and concrete filled with steel tube composite structures increasingly and widely used, Steel truss arch bridge is built in the attempt. The welding is commonly used in pipe connections and joints. For the welding residual stress, the structural properties may be reduced in welding areas, such as structural anti-fatigue properties, stress corrosion resistance and stability behavior. Meanwhile, the welding residual deformation also directly affects the machining accuracy and stability of components. Out of the economic and safety, it is of great importance to recognize and control of the distributions of residual stress and deformation of welding structures.First of all, it describes the concept of welding residual stress and its causes and impacts to welding structures, as well as the characteristics of numerical simulation of welding residual stresses, the study history about the temperature field and stress field. Secondly,it studies the theories of heat transfer process and the finite element calculations method of temperature and stress field. Thirdly, based on the3D FEM simulation and analysis of welding temperature field and stress field to the most commonly used steel tubular T joints in ANSYS, it gets the temperature field and dynamic stress in welding process, the distributions of post-weld residual stress and deformation. It studies the element types, meshing, time step and boundaries. And it takes fine meshing in areas nearby the heat source and rough meshing away from heat source with3D entities element without intermediate node, to stimulate welding heat load and metal filling in welding process with local coordinates and element active and killing technology. The double ellipsoid heat source model is utilized to simulate the moving of welding heat by ANSYS APDL, weld temperature field and stress field, the distributions of residual stress and deformation of the T-joints, which is almost in accordance with results in theory. Finally, it varies heat source parameters and obtains the effects and distributions of welding speed and weld width to the welding residual stress and deformation, which is helpful for the improvement of welding technology and optimization of welding structures.