Numerical Simulation Of Temperature Field And Stress Field And Deformation Of Steel Sheet By Friction Stir Welding With Composite Heat Source

With the development of welding technology,the "Green Welding" was put forward,the important research content of the concept was reducing the arc welding process,dust,noise and other harmful substances,that was to reducing the damage to the body of an operator.Then the friction stir welding was invented,and has widely used for the shortest time.The friction stir welding process doesn't have arc,dust and toxic gas and other defects of traditional fusion welding.And the FSW is a technology of solid connection,so that can avoid hard phase which is caused by metal melting.At present,the main application of FSW is about aluminum alloy,magnesium alloy and other low melting point metal materials,and has almost no actual engineering applications in the high melting point metal materials.In order to expand the application of friction stir welding in high melting point materials,this paper studies the numerical simulation of high melting point material of Q235 steel sheet which is connecting by friction stir welding with composite heat source:(1)According to the mechanism of friction stir by the shoulder without pin,the heat source model which the heat input is nonlinear increased following the anti Gauss from the center to the edge of the shoulder is put forward.Using the finite element analysis software ANSYS to analysis the temperature field of FSW which has recombination heat input of TIG+FSW+bottom heating.Using the thermocouple temperature measurement system which is designed by self to measure the thermal cycle curve of the feature point on the workpiece.And comparing with the curve by simulation,the results show that the fitting degree is very high,demonstrating the validity of the heat source model and cooling conditions.(2)Using the order(indirect)coupling method which applying the thermal analysis results as the load to the analysis of the structure to calculate the variation of stress and residual stress field about welding process of high melting point materials sheet steel with composite heat input,and getting the law of the stress changes.Calculating the amount of deformation by thermal elastic-plastic calculation method of thin plates after welding,using a dial indicator to measure the relative deformation of the butt plate,the results show that the deformation are compared verifying the correctness of the structure analysis model and constraint load.(3)Through single factor comparison test and the method of the orthogonal simulation test to analyze the the influence law of weld temperature changes and degree by changing different weiaing parameters in the weiaing process.Researcn snows max the cnange of the process parameters does influence the weld temperature and make the peak temperature overall upward or downward.The effect degree of the factors that affect welding temperature is welding speed>current value of TIG>velocity of rotation.