Research On Welding Deformation Mechanism Of Complex Aluminum Alloy Thin Plate Structures

The body of the high-speed train is welded with aluminum alloy profiles.Due to the material properties,the welding deformation is very obvious.The side wall is the most complex structure and process components.It is made of 5 pieces of hollow aluminum alloy profiles.Welding process parameters,fixture positioning parameters,welding sequence parameters,etc.will have an important impact on the welding deformation,resulting in difficult control of welding deformation.Current research does not completely solve this proble.Therefore,in order to solve the problem of welding deformation of aluminum alloy car body,this article takes the high-speed train body side wall welding as the research object.Through the fixture positioning and welding sequence parameter analysis,the fixture positioning and welding sequence of the residual stress and deformation influence mechanism of the side wall welding are obtained.The main contents of the research are as follows:1)Established the maximum residual stress and deformation fixture positioning model.Firstly,by means of the layout of the side wall fixtures,it was determined that the object of study was a part of the side wall.The Gaussian heat source was used in ANSYS for simulation and compared with the actual data.Then using ANSYS to simulate the welding process of the side wall under the existing conditions,established the welding residual stress and deformation analysis model,and finally established the maximum residual stress and deformation fixture positioning parameter model by changing the clamp constraint distance.The welding distortion decreases with the reduction of the clamp constraint distance,but it is not unlimited.The optimal fixture constraint distance was 1.8m2)Obtained the relationship between welding residual stress and deformation and welding sequenceFirst of all,through the decomposition of the welding sequence problem,the relationship between the maximum residual stress and the deformation and the welding sequence was studied from three aspects of the weld area,the outer area of the weld,and the welding sequence of a single weld,and then passed through two welds.The analysis of the interaction between the seams simplifies the study of welding sequence problems.The conclusion is drawn as follows:The near-seam area is only affected by its own welding.Far away from the weld area is only affected by the adjacent weld,and the deformation from left to right is minimal3)Optimization of fixture positioning parameters and welding sequence parameters.Firstly,the influence of the longitudinal parameters of the fixture on the magnitude of the welding deformation was analyzed.The different fixture restraint methods resulted in large changes in the welding deformation..Then,the influence of the lateral parameters of the fixture on the magnitude of the welding deformation was analyzed.When the lateral restraint position was in the middle of the plate,the welding deformation was minimal and more regular.Finally,using the obtained welding sequence results,the welding sequence was optimized.The welding sequence optimization results show that one-way cross welding results are better.