多个裁剪参数曲面的有限元混合网格剖分法

摘要

According to the character of die shape, based on the mathematical model of multiple trimmed parametric surfaces, which is created by CAD/CAM system, an algorithm for generate mixed mesh of triangles and quadrilaterals for finite element analysis is presented. The trimmed parametric surfaces are discreted into polygons, which are controlled by the parameters of maximum edge length, minimum edge length, distance tolerance and angle tolerance, etc. The adjacent relation between surfaces is found and merged by surface-curves, consequently, a model represented by boundary is created, the polygons are updated by surface-curves, and mixed mesh is generated by these polygons. The resultant mesh is conformal, without crack and overlap between the adjacent surfaces.%根据冲压模具形状特点，对由CAD/CAM系统建立的冲压模具的多裁剪参数曲面数学模型，提出了一种符合冲压成形有限元分析需要的三角形和四边形混合网格剖分算法.按几何离散控制参数即最长边、最短边、距离误差和角度误差，将多裁剪参数曲面离散为多边形集.利用曲面曲线查找裁剪参数曲面相邻关系，建立B-Rep表示的曲面几何模型，并更新多边形集.然后由多边形集得到三角形和四边形混合网格，结果网格单元是相容的，在相邻裁剪参数曲面边界处无裂缝和覆盖.