Finite Element Simulation For Laser Curve Forming Of Sheet Metals

Laser forming is a new type of sheet metal forming process. The sheet metal is formed by asymmetrical thermal stresses. The stresses are induced by the temperature grads of HAZ when a scanning laser beam goes along the sheet. And it bases on the properties of material's thermal expansion. Compared with conventional forming process, it has many advantages. During the laser forming process, no external forces and hard dies are required. With this process, a variety of shapes can be formed, and even brittle materials may be deformed. Consequently, the engineering field and numerous scholars pay extensive attention to it.This dissertation uses the FEM software ANSYS to simulate the whole process of single laser scanning on sheet metal. It analyzes the deformation features and 3-D temperature fields of laser forming process. To optimize the process parameters, Optimization method is introduced in numerical simulation. The contents are as follows: (1)The FEM software ANSYS is used to simulate the laser forming of rectangular sheet metal. The results of simulation show that the change of temperature field in the heat of uniformity distributing is more acute than that in the heat of gauss distributing, and the finally distortion displacement is comparatively larger. (2)ANSYS Parametric Design Language (APDL) is used to express the moving model of laser beam based on process route, the initial meshing and adaptive remeshing are conducted to guarantee the calculating precision and effect. (3)The program above is used to simulate the laser forming of sheet metal based on special curving process route. Compared with the linear process route, the result of simulation shows: the material in upper surface of sheet metal generates the distortion of landscape orientation, the size of which is larger than that of the material in lower surface, and the size is larger than the distortion of line scanning. The cause is that the heating area of the curve scanning is larger than the line scanning. (4)The dissertation uses numerical simulation to research the affection ofprocess parameter and material properties on bending displacement. The results show that the energy density is increased when increasing the laser power while other parameter unchanged, and so resulted in bigger displacement. Increasing scan velocity while laser power unchanged, the absorbed energy is decreased, and the bending displacement is decreased. Increasing beam diameter while laser power and scan velocity unchanged, the bending displacement is decreased. The bigger energy density leads to bigger bending displacement. (5)The dissertation uses Visual Basic to encapsulate the commands of ANSYS, and develop the FEM analysis system of laser forming of sheet metal. In this system, the optimization module may optimize the process parameters of laser forming and the process route.