Design Intent Maintenance and Topological Entities Naming in Design Process

One of the fundamental issues with history-based parametric feature modeling is how to effectively name and identify referenced topological entities.And its key point is how to maintain implied design intents during design process.The interrelationship between design process and topological entities is analyzed,and the topological entities' change types and identification required for capturing design intents are given.Two concepts,the directed isoparametric lines(DIL) on a surface and the face-face relationships(FFR) based on DIL,are introduced.By using the local topological information and geometrical information,a face-based topological entities naming approach is proposed,which provides more design intent information for topological entities identifying.The adjacent faces of a topological entity are divided into active face set and non-active set.Based on the continuity of the design variation,the implied design intents are expressed in terms of sub-set relationship between related face sets.A sub-set relationship principle for identifying topological entities is put forward.The proposed approach has been tested by a number of test examples,which show the approach can deal with the situations with topological changes more effectively.