Based On The Geometric Shape Of The Parametric Finite Element Modeling And Surface Grid Generation Method And Realization

Finite element method is a popular numerical analysis method, which is widely applied in many industrial fields such as aviation, architecture, mechanics, electronics and chemistry. It has become the criterion of the analysis and design optimization of structures, and finite element analysis (FEA) software has become the most important part of CAD/CIMS system.Finite element modeling (FEM) is the pre-process of FEA. It is based on CAD system, and ties FEA technique to CAD system. Most of finite element modeling methods are static at present. Once the design engineers finish the finite element model, it will be very difficult to modify the model. This static finite element modeling method doesn't need the requirement of the dynamic design of product in the modern industry. Otherwise, most work on the surface mesh generation is based on the single trimmed surfaces, and the work to closed surface and combined surface, which are very popular in engineer, is very few.To solve the problems mentioned above, the author studies the problems carefully and gives out some solutions.A method of surface triangulation based on the traditional mapping approach is presented in this thesis. The method has four features: 1) Virtual movable boundaries are given to assist the mesh generation on closed surfaces. 2) For making the meshes consistent on the common boundaries of adjoining surfaces, a new approach of boundary discretization is employed. 3) The boundary-representation structure is adopted to fulfill the mesh generation over combined surfaces. 4) The quality of surface meshes is improved by point creation on 3D scan lines and diagonal swapping procedure. An application to mesh surfaces only depending on geometries is developed. The application is tightly integrate with the CAD package AutoCAD from Autodesk Corporation.A method of parametric finite element modeling for shape optimization is presented in this thesis. The method has three features: 1) The dimensions used in commercial CAD system are selected to be the design variables of shape optimization.2) A mapping between geometry objects and finite element objects such' as meshes, structure properties is set up to assist in defining finite element models on geometries.3) An automatic mesh generator and a method by which structure properties is assigned from geometry objects to finite element objects automatically are used to update finite element models during the optimization process.