| At present,in the field of aerospace,a large number of lightweight high-strength aluminum alloys are used in lightweight design.In order to ensure the welding quality and strength between the fuel tank and the various pipelines,a flanging hole was often processed on the tank body first.However,due to poor formability of aluminum alloys and other light alloys under the room temperature,the traditional flanging process often causes cracking failure in the mouth area of the vertical wall.The process was usually complicated and the forming quality cannot be guaranteed.Electromagnetic flanging is a typical high-energy-rate forming process.The advantages include the characteristic of improving material plastic formability,and high processing efficiency.Most of the predecessors focused on the study of the forming process of regular hole flanging,and the electromagnetic flanging of shaped holes and the design of prefabricated holes were still in the exploration stage,and this article studies them in depth.The flanging test of AA5182 aluminum alloy: The quasi-static and electromagnetic elliptical hole flanging process experiments were carried out to study the influence of discharge energy and other process parameters on the quality of elliptical flanging.The comparison of electromagnetic and quasi-static technology shown that magnetic pulse forming can increase the forming limit of the material and increase the height of the flange.Combined with the hardness test to explore and compare the basic law of the quasi-static and electromagnetic sample deformation area.During the process test,it was found that the design method of pre-made holes with equal neutral layer could not obtain the process samples with the same height of flanging.The establishment and verification of the FEA model: The constitutive model of AA5182 aluminum alloy material was obtained through high-speed tensile test,and on this basis,a numerical simulation model of aluminum alloy electromagnetic flanging was established with the help of the electromagnetic(EM)module in LS-DYNA.The speed-time relationship obtained by DIC(Digital Image Correlation)and PDV(Photonic Doppler Velocimeter)measurement methods verified the accuracy of the electromagnetic flanging numerical simulation model established in this paperAnalysis of deformation of elliptical flanging: using finite element simulation technology to study the dynamic evolution process of the end profile of the elliptical electromagnetic flanging part,and the basis of the evolution of the end profile was found in electromagnetics by combining with the electromagnetic field distribution law.In order to further comprehensively analyze the deformation process of the sample,combined with the numerical simulation model to analyze the deformation history of the sample and the straight arm area of the sample.At the same time,the strain path and three-way strain of the deformed area were analyzed by numerical simulation model,revealing the law of flanging deformationDesign and application of new prefabricated holes: A new elliptical prefabricated hole design method was proposed based on the deformation law of elliptical flanging,and an optimal polynomial prefabricated hole proxy model was established according to the numerical simulation sample data.In this paper,the new elliptical prefabricated hole design method was applied to solve the uneven defect of elliptical flanging.Its flanging result was in good agreement with the design value and could solve the problem of elliptical flanging flatness.The optimal polynomial prefabricated hole proxy model was applied to circular and runway-shaped electromagnetic flanging,and its flanging results fluctuate slightly above and below the design value,which could provide new ideas for the prefabricated hole design method. |
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