The Research Of Re-Evaluation Mechanism In Semantic Feature Modeling System

To the engineering designer, semantic feature modeling system, which adopts completely semantic constrains to define feature and create model, can satisfy all of their intents. It uses feature dependent graph as data model, cell-based model as geometric model, and view model as user interface, but it is more complex than the former system based on parameter and history. Designing model means modifying, and modifying causes re-evaluation, so its re-evaluation is an important part for the system. In the course of re-evaluation, not only must it be edited easily but also it can maintain its high efficiency and semantic conformity. The key problems are how to maintain its semantic conformity, how to protect designer's intents, how to assure the stability and integrality of product information, and how to improve its efficiency. This paper will research the key issues for the model re-evaluation from the two aspects , theory and system design. We will combine the cell-based geometric model and FDG-based data model to analyze them, and bring forward the new methods and new thought for the model's re-evaluation, with the associated algorithm. Its content includes the followings: the updating and analysis for the FDG, the analysis mechanism of constrain-based feature semantic, the research of cell-based geometric model, and the research of updating sequence, the re-evaluation research for the cooperative design through network, and so on. And based on the original data structure and algorithm in HUSTCAID, some new algorithm can be achieved in VC++ language. The research result can be applied in HUSTCAID, and have accelerate the speed of design and can contribute to the enterprise's profits; furthermore, it can have some effect on the Graphic & CAD field in demotic even international area, and promote the CAD technology to advance more.