摘要：Naming topological entities and the validity maintenance of model are two important issues in Computer Aided Design, which can make a semantic feature model conform to all constraints correctly. In this paper, a new mechanism of naming topological entities based on face features is proposed. Based on the corresponding mechanisms for naming topological entities, the methods of coding entities, sub-entities and virtual entities are given. The mechanisms for maintaining the validity of semantic feature operations are described. Sub-edges, sub-faces, virtual faces and virtual sub-edges are applied to process the problem of face obliteration. Sub-edges and virtual edges are used to process the problem of edge obliteration. After the mechanisms for naming topological entities and the methods of validity maintenance are applied to HUST-CAID system, its modeling performance is improved and the feasibility of the proposed mechanisms and methods above is also proved.
