Research On Some Questions Based On Mesh Generater In KMAS System

Numerical simulation based on the finite element method may vividly describe the flow-behavior in Sheet Forming Processes and reveal the distributed and changed ruler of physical field of deformity and dies, provide scientific basis for die design. Many steps in the automobile covering die design system actuated CAE must based on the finite element mesh, therefore, the finite element mesh automatic generation is the foundation of the automobile covering die design system. The quality of the mesh has important influence to die design and the result of the following finite element analysis.Combining the National Natural Science Foundation of "The Basic Theory, Computational Methods and Key Technologies of the Press Forming and Die Design" (authorized number: 19832020)the National Excellent Young Scientists Fund" Based on KBE Ramming Mold CAD Expert System Theory, the Theory of Forming for Polymer Metal and Research of Computational Methods " (authorized number: 10125208) as well as Jilin University '985 project' Automotive Engineering Science and Technology Innovation Platform, we do some researches on the technology of mesh generation in automobile body cover forming and simulation of casting technology commercialization software KMAS:The form of IGES in the process of data translation always make errors or loses data, especially, when the parameter values of periodically rotate surface boundary are 0 or 2Ï€by the form of IGES often makes errors. If we don't adjust the values, the meshes generation will have the dislocation situation and can't be applicable to the finite element methods. Therefore, the repairing data of the values is very important. Using the continuity property of the parameters on the surface boundary, we repair the parameter values of the boundary on the periodically rotate surface, then, the boundary points and their corresponding parameter values can be accurately matched.The boundary of trilateral or four sides curved surface is always uneven. When meshing on the UV parameter region, the side which has sharp curvature is very easy to form long element. Sometimes, the nodes of the element are not in the surface and the element is not applicable to the finite element method. With the aid of ACIS platform, combining the parameter thrice spline curve, the region of the UV parameter is mapped to the neat triangle or quadrangle, we can mesh in the neat triangle or quadrangle, then the neat region is mapped to the region of the UV parameter, the nodes in the region of UV parameter are mapped to the original surface using transfinite interpolation method. After such processing, the quality of the mesh has been evidently improved.The mesh generation is fast by the traditional UV parameter method, but the quality of the mesh is often very bad. Using the relationship of the length and topology among sides on the generating surface, the quadratic mapping method is put forward. Using this method, the region is mapped to the quadratic plane, the latter is more approachable the original surface than the former. Therefore, the quality of the mesh by the quadratic method is better than the quality of mesh by the traditional UV parameter method.The Incremental Solver in the KMAS has its request to the mesh: the finite element mesh must be able to precisely simulate the curved surface. Therefore, so the contact algorithm has the higher solution precision. The scanline algorithm of the mesh generation proposed in this article can meet this demand well and has a good speed. We carry on the algorithmic analysis to the smallest angle most superior algorithm. If the polygon region is a convex polygon, then the algorithm time and the spatial order of complexity are O(n), In the worst situation; the algorithm time and the spatial order of complexity are both O(n~2).