Research On Rigid-Visco Plastic Meshless Galerkin Method And Key Simulation Techniques For Metal Forming Process

The technology of metal forming processing plays an important role in metal part manufacturing. Its advantages are not only in its high productivity, stable quality, and low cost of raw and processed materials, but also in its characteristics of improving the microstructure performance dramatically. With the development of computer technology and computational methods, the finite element method (FEM) gained great achievement and was applied wildly in many engineering fields. Although great success in the metal forming process numerical simulation is achieved by FEM, the mesh distortion will be inevitable for the accumulation of the metal deformation. Then many difficulties will be occurred in FEM analysis for dependence of the approximation precision on the mesh. Compared with FEM, the meshless approximation based on discrete point information has advantages in the simulation of large deformation problems with mesh distortion for getting rid of the reliance on the mesh. Simultaneously, meshless method is more flexible and simpler than FEM in data prepare for the problem simulation and post-process of simulation results.The meshless method, a newly developed numerical method, was used to the simulation of metal forming process after decade's development, and some progresses were obtained. But there are still many key techniques, which need more attention for the complexity of the metal deformation in unsteady metal forming process. Especially when the deformation is more severe or metal flow is more complex, the approximation precision of the velocity field and integration precision of deformation domain will be deteriorated for the severe un-uniformity of the metal flow and complexity of the deformation zone. Thus simulation error will be occurred. So, the study focused on the development of the rigid-visco plastic meshless Galerkin method and its key techniques for unsteady large deformation metal forming process.The meshless Galerkin method is introduced into the analysis of the metal forming processes. Under the hypothesis of the rigid-visco plastic material, a rigid-visco plastic meshless Galerkin method is developed. The velocity field is approximated by Moving Least Square (MLS) method, Reproducing Kernel Producing Method (RKPM) and Radial Basis Function (RBF) in which MLS and RKPM is modified by the transformation method in order to employ the essential boundary condition directly. An arctangent frictional model is used to describe the frictional boundary condition. For the...