| Magnesium alloy have become modern industrial products ideal material with its light weight, high strength, good stability, beneficial to the environment, the recyclable characteristics. Especially in the automotive, aerospace and electronics industries, as a light structure and functional materials, its application is increasing. But because of the magnesium alloy is six-party row (CPH) structure and at room temperature its plasticity is poor, it is difficult to make the magnesium alloy forming under the cold state. In recent years, the researchers found that the plasticity of the wrought magnesium alloy is markedly improved under the heating conditions, and some literature is studying on thermal micro-behavior of the magnesium alloy, but the research on laser thermal forming of the wrought magnesium alloy sheet metal is little. Laser bending is a forming technology which makes use of a thermal stress and thermal strain to achieve sheet metal bending in recent year, and it needs no die and external force. The laser beam energy has good controllability. Laser technology is used in forming of magnesium alloy sheet, this can full play the unique advantages of the technology.This paper is on the basis of laser bending, an experimental study have been done about laser bending of AZ31 magnesium alloy sheet metal. The experiments get the effect of laser processing parameters on bending angle. Also get the effect of plate geometry size, and scanning path on bending angle. In order to further reveal the law of sheet metal bending deformation, the three-dimensional elastic-plastic finite element is used to numerical simulation, and have revealed the change of the temperature field, stress-strain field, the displacement field with the changes of time under different technical parameters of the laser bending process, and have explained some experimental phenomena. The work includes the following contents:(1) The geometric model of laser bending sheet is established. The plastic deformation in the upper and lower surface is analyzed during the heating and cooling process. The analysis formula is abstained through the elastic-plastic deformation of upper and lower surface and one-dimensional thermal conduction equation, and have a comparison with the experiment results.(2) The laser bending experimental study of magnesium alloy sheet. The different laser parameters (laser power and scanning speed and spot diameter), and sheet parameters (sheet width and thickness) affect the bending angle.(3) Establishment of the finite element model of laser bending process. 3-D finite element model of temperature and displacement field are established, and have revealed the change of the temperature field, stress-strain field, the displacement field with the changes of time under different technical parameters of the laser bending process. The process of sheet laser bending is simulated.(4) The research of laser sheet convex bending. Based on the finite element analysis, the heating region of the two forms of deformation is studied comprehensively. In order to achieve the convex bending of sheet metal, a lot of experiment have been done about the deformation behavior of magnesium, and has got the empirical formula to judge magnesium alloy sheet bending direction; it provides a theoretical basis for the selection of laser forming parameters.The work in this thesis supply experimental and theoretical foundation for laser bending the paper presents the choice methods of laser process parameters and the laser parameters under different forms of deformation; the use of finite element simulation is used to analysis laser bending process. It has a certain guiding significance to the practical application of laser bending of magnesium alloy sheet.
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