Numerical Simulation Of 2219-T87 Aluminum Alloy Inertia Friction Plug Repair Welding

Drawing type inertia friction plug repair welding is a kind of solid-state welding technology which is mainly used for repairing welding defects.It has the advantages of narrow welding heat affected zone,good comprehensive performance,small welding deformation,short welding time and high production efficiency.Therefore,it is applied to repair the "keyhole" defects on the welds of Rocket Tank after friction stir welding.It is widely used in the field of aerospace.Traditional research methods through a large number of welding process tests,the different welding parameters of the joint situation for comparative analysis,which requires a lot of time and resources.With the rapid development of computer technology,the finite element numerical simulation method is used in the research of welding process.The numerical simulation method can not only save time and shorten the test cycle,but also avoid the blindness of a large number of process tests.In a short time,it can realize the screening of a large number of welding process parameters,and provide the optimal welding process parameters for process tests.Based on the elastic-plastic finite element theory,this paper establishes a three-dimensional simulation calculation model for the welding process of pull-out inertia friction plug.With the aid of DEFORM-3D finite element simulation software,2219-T87 aluminum alloy is taken as the research object.After the local mesh refinement of the friction area between plug bar and plug hole,the numerical simulation calculation is carried out.At the same time,the same welding parameters are selected for the process test,and the temperature indicated on the plug bar and the workpiece is measured by the infrared thermometer.The simulation results are consistent with the test results,which verifies the feasibility and accuracy of the established three-dimensional simulation calculation model for the pull type inertia friction plug repair welding.The temperature,stress-strain and axial displacement of the plug bar and the workpiece were obtained by numerical simulation.The simulation results show that the high temperature distribution on the friction surface is 406.1?637.1? at the initial welding speed of 7000r/min,399.5?453.8?,401.9?629.5? and395.8?620.0? at the initial welding speed of 5800r/min,6400r/min and 6800r/min,respectively,and the temperature distribution on the friction surface is 395.8?453.8? with the other welding parameters unchanged The greater the rotating speed,the more the friction heat,the higher the temperature on the friction surface and the larger the high temperature range;the greater the influence of welding pressure on the formation of the joint morphology,the greater the equal effect variable value on the plug bar and workpiece under the welding pressure of 68 MPa,the greater the "flash" on the plug hole is than the two groups with the smaller welding pressure;equal effect The stress distribution is mainly concentrated in the cone angle and neck area of the plug bar and the plug hole of the workpiece.The value range of the equivalent stress on the plug bar under different parameters is mainly between 40.4 and 65.2MPa.The value range of the equivalent stress on the plug hole is mainly between 45.5 and 70.5MPa.In the middle range of the equivalent stress distribution,the metal materials on the plug bar and the workpiece have large plastic deformation,and the plug bar has obvious plastic deformation The metal material on the friction surface of the plug hole is extruded to form a "flying edge".Other welding process parameters remain unchanged,and the axial displacement of plug bar and workpiece plug hole changes under the initial welding speed of 5800r/min,6400r/min and 6800r/min.after welding,the axial displacement of plug bar is 13.3mm,14.1mm and 18.7mm respectively,and the axial displacement of workpiece is 1.6mm,2.3mm and 3.5mm respectively.It is found that the larger the welding speed is,the larger the axial displacement of the metal materials on the plug bar and the workpiece is,which means that the axial elongation on the plug bar and the workpiece increases with the increase of the initial welding speed;the equal effect variation value distribution on the plug bar under the welding pressure of 60 MPa,64MPa and 68 MPa is 1.98,3.50 and 5.09 respectively,and the equal effect variation value distribution on the workpiece is 2.78,3.06 and 4.18,it is found that the value of equal effect variation distribution on plug bar and workpiece increases with the increase of welding pressure.Through comparison,it can be concluded that when other welding process parameters remain unchanged,increasing the initial welding speed and welding pressure within a certain range,the temperature on the friction surface is higher,more metal materials with plastic deformation occur on the plug bar and workpiece,and the quality of the joint is higher.The purpose of this paper is to provide a new optimization method of welding process parameters for repairing keyhole defects in friction stir welding of rocket tank,and to provide a scientific and effective theoretical basis for selecting the optimal welding process parameters and obtaining high-quality welds.