あいまい知識処理手法と計算幾何学に基づく大規模自動要素分割法 : 二次元平面,三次元ソリッドおよび三次元シェルへの応用

抄録

This paper describes a novel automatic finite-element mesh generation method for large-scale complex structures based on fuzzy knowledge processing and computational geometry. Its mesh generation process consists of three main subprocesses: ( a ) : definition of an analysis domain, ( b )generation of nodes, and ( c ) generation of elements. Practical three-dimensional CAD systems for three-dimensional solids and shells are employed for subprocess ( a ) . In subprocess ( b ), nodal densities of locally optimum nodal patterns are first chosen from the nodal pattern database of the system, and secondly these nodal densities are superposed on one another by using fuzzy knowledge processing. Thirdly, nodes are generated by the bucket method, whose processing speed is almost proportional to the number of total nodes. In subprocess ( c ), either triangular or tetrahedral elements are generated in a two-or three-dimensional domain, respectively, using the Delaunay triangulation whose speed is also proportional to the number of total nodes. In the cases of two-dimensional plane and three-dimensional shell, triangles can be converted into quadrilaterals. To demonstrate the practical performance of the present method, it is applied to mesh generation of a nozzle corner of a nuclear pressure vessel, and that of a portion of an automobile body.