| Welding is a kind of advanced manufacturing technology,which plays an important role in machining field.Compared with carbon steel,the thermal-physical properties and mechanical properties of aluminum alloy are obviously different,because the linear expansion coefficient of aluminum alloy is about 2 times of carbon steel,the thermal conductivity is about 4 ~ 5 times of carbon steel,the elastic modulus is about 1/3 of carbon steel,the high-temperature yield strength is relatively low.It is the different properties of these materials that make the welding deformation of aluminum alloy easier in the welding process.Especially for large and complex aluminum alloy welded structural parts,it is of great significance to reduce and control the welding deformation through structural design optimization and welding process optimization because of the complex factors affecting the welding deformation.Therefore,based on the above background and the status quo,in order to be able to accurately predict welding deformation of large aluminum alloy welded structure,establish a calculation method of typical welded joint of aluminium alloy inherent deformation,is to further implement the inherent strain gauge in the application of large welding structure,fast and exact forecast for welding engineering structure provides the basis for welding deformation.In this study,aiming at the problem that the aluminum alloy thin plate is prone to buckling deformation in the welding process,a new method to obtain the inherent deformation by means of the combination of cutting method and inverse analytical method is studied.In order to verify the scientificity and appropriateness of the research method,this paper takes TIG remelting and MIG aluminum alloy sheet as examples to summarize the theory and analyze the calculation results of the developed method.The results show that the methods proposed in this paper can obtain more accurate natural deformation results despite the different deformation characteristics of TIG remelting and MIG aluminum alloy sheet after welding.Specific as follows: first,the research and development of thermal elastic-plastic finite element method is used for TIG welding and MIG welding residual plastic strain and residual stress distribution in comparison,research has shown that the residual plastic strain distribution in the weld and its near a narrow area,get rid of both ends caused by end effect of plastic strain distribution range compared with the plate inside the other position is more narrow,the overall equivalent plastic strain distribution along the weld direction basically uniform.Due to the narrow distribution range of plastic strain caused by welding,it can be inferred that even if the size of welded test plate is moderately reduced by cutting method,the change of plastic strain will not be affected.Secondly,when the welded joint is cut into several parts,the instability deformation of the joint will disappear or decrease due to the release of elastic potential energy.This proves that in general,the buckling deformation caused by welding is elastic buckling deformation.Thirdly,the natural deformation of TIG remelting and MIG aluminum alloy sheet was calculated by extracting the deformation of the cutting model.The results show that the components of the inherent deformation of TIG and MIG welding plates can be obtained by using the inverse analytical method of cutting by taking the deformation obtained by finite element analysis after cutting as a known parameter.At the same time,this result is substituted into the elastic finite element program as the initial deformation distributed near the joint,and the obtained welding deformation trend is consistent with the results of thermal elastoplastic finite element analysis.This result shows that the method of natural deformation obtained by combining the cutting method and inverse analysis is a practical and effective scientific method. |
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