Numerical Simulation Of Welding Residual Stress Of Aluminum Alloy Plate And Its Evaluation And Control

Because of the locality and instantaneity of welding heating,there are inconsistent plastic strains in the welding process,and uneven distribution of welding residual stress is formed after cooling.Especially for aluminium alloys with high thermal conductivity and high thermal expansion coefficient,it is easier to produce large inconsistent plastic deformation during welding.Therefore,it is of great significance to study the evolution process and formation mechanism of residual stress and strain in aluminium alloy welding process for evaluating and reducing residual stress.Based on the basic theories of fluid mechanics,heat transfer,stress and strain,this paper carries out finite element numerical simulation on the basis of theoretical analysis,establishes a three-dimensional welding finite element model of heat source movement,and studies the formation process and influencing factors of welding residual stress.The main work of this paper is as follows:The influence of the flow characteristics of molten metal liquid produced by the coupling of buoyancy,electromagnetic force,Marangoni force and arc force on the welding temperature field was investigated.The distribution of flow field and temperature field of molten pool in welding process was compared and analyzed to find out the law of influence of flow field on temperature field.The results show that with the increase of current and stirring speed of molten pool,the heat diffusion rate around the molten pool increases,the heat flow is more dispersed,the peak value of temperature field is reduced,but the volume of molten pool is increased.The influence of welding path on residual stress was studied.Because different welding paths will change the temperature field generated by the input heat,and then affect the residual stress field.Taking the sectional welding path as the starting point,the evolution law of temperature field and the distribution law of longitudinal and transverse residual stress field under different welding paths are compared.The analysis results show that the sectional welding can effectively reduce the peak value of temperature field and reduce the residual stress level,and the outward welding from the center of the welding workpiece is the optimal path.By designing orthogonal optimization experiment,the influence of welding voltage,welding current and welding speed on welding residual stress field was analyzed,and the optimal combination was obtained.Based on the optimalcombination of welding process parameters,the influence of groove factors on welding residual stress field was studied.The results show that the residual stress of welded I-groove is less than that of Y-groove,and the residual stress of Y-groove increases with the increase of groove angle.