Simulation Analysis Of Friction Stir Welding Based On ABAQUS Software

Friction stir welding(FSW)is a new solid-state bonding method.It was invented by British Welding Research Institute in 1991.In recent years,a lot of research has been done on its welding process at home and abroad.In general,there are two methods to simulate the welding process of FSW which are the quasi-static method of loading simplified heat source and the dynamic method of simulating the stable welding stage.However,there are few reports on the dynamic method of fully simulating the whole welding process.In this paper,based on thermal-elastic-plastic method,JC constitutive equation and penalty contact algorithm,a new dynamic thermal-mechanical coupling finite element model is proposed for the finite element analysis of complete welding processes.The analysis results are compared with those of the traditional simplified heat source and the experimental results of residual stress.Then,it is analyzed by traditional method that is the influence of welding parameters(welding speed,rotating speed,downward pressure and shoulder radius)on the temperature field and residual stress field in the welding process.Finally,the optimization model of welding parameters is established,and the orthogonal experimental optimization method is used to optimize the welding parameters.The study results are shown as follows:(1)the analytical results of the dynamic thermal-mechanical coupling finite element analysis model presented in this paper are closer to the experimental results than the traditional methods.It is proved that the finite element model established in this paper is correct and reasonable;(2)in the preheating stage,the high temperature zone of the temperature field concentrates in the weld zone,and the peak temperature reaches about 400?,which is located near the welding toe of AS zone.In the processing stage,the temperature gradient of the front side of the mixer head is large and its distribution range is small,while the temperature gradient of the rear side is small and its distribution range is large;(3)it is shown a double peak trend that is the distribution curve of longitudinal residual stress field on path EF after welding.The peak stress reaches 129 MPa,which is located on the side near AS zone and shows a tensile stress state in the weld zone.The peak value of transverse residual stress is significantly lower than that of longitudinal residual stress;(4)increasing the radius of the stirring head,the rotational speed of the stirring head and the pressure under the stirring head increase the peak value of the temperature field and the peak value of the longitudinal residual stress after welding.The peak value of temperature field decreases with the increase of welding speed,but the peak value of longitudinal residual stress increases after welding;(5)through orthogonal optimization experiments,it is concluded that the order of significant degree of influence of welding parameters on maximum longitudinal residual stress is shoulder radius,rotation speed,welding speed and downward pressure.The optimum combination of welding parameters are 0.005m/s,2400r/min,6000N downward pressure and 0.004m shoulder radius.The research results of this paper lay a theoretical foundation for the further study of the welding process of friction stir welding of aluminum alloys.At the same time,it provides a new idea for establishing a more practical finite element model.