三维实体仿真建模的网格自动生成方法

有限元网格模型的生成与几何拓扑特征和力学特性有直接关系。建立网格模型时，为了更真实地反映原几何形体的特征，在小特征尺寸或曲率较大等局部区域网格应加密剖分；为提高有限元分析精度和效率，在待分析的开口、裂纹、几何突变、外载、约束等具有应力集中力学特性的局部区域，网格应加密剖分。为此，该文提出了基于几何特征和物理特性相结合的网格自动生成方法。该方法既能有效地描述几何形体，又能实现应力集中区域的网格局部加密及粗细网格的均匀过渡。实例表明本方法实用性强、效果良好。

3D Automatic Mesh Generation Method for Solid Object Simulation Modeling

With the development of automatic 3D mesh generation, more attention has been paid to full 3D adaptive finite element analysis, which is able to adjust the mesh according to the results of analysis and improves the solution quality in an optimal manner. But in order to achieve the target accuracy, adaptive finite element analysis costs more CPU time if the initial mesh is coarse. It will cost less CPU time if the coarse mesh is replaced by refined mesh. Theory and practice show that the mesh refinement is associated not only to geometric topological features but also to mechanics properties. In order to describe original geometric model more exactly, the mesh should be refined in the zones of small size or large curvature. In order to improve the accuracy and efficiency of finite element analysis, the mesh also should be refined in the zones with holes, slots, concave, crack, load, restriction, where exist stress concentration or high stress gradient. So the automatic tetrahedral mesh generation method based on geometric features and mechanics properties has been developed in this paper. The main procedures are as follows: (1) The zones and rules of mesh refinement are defined by recognizing the geometric features and mechanics properties; (2) The node sets of graded density are generated automatically in the refined zones. (3) The node sets of the solid surface are generated by Delaunay triangulation in the whole zones (except the refined zones). (4) The initial tetrahedral meshes are generated from the former node sets by Delaunay method. (5) The optimized tetrahedral meshes of the whole solid are generated. In this process, the nodes are generated in the initial mesh and the optimized tetrahedral mesh are generated accordingly. As a result, the tetrahedral mesh modeling can describe geometric features exactly and the mesh in the zones, where the stress is concentrated, can be refined gradually by this method. Examples show that the mesh refinement is satisfying and the application is widely.