Research On User-defined Feature And Parts Library In Semantic Feature Modeling

Design work is often variant or a series design, some design results have been frequently used in the new design. According to incomplete statistics, more than 90% of the structural elements of the parts are common or standardized, 70% -80% of the parts are similar. In product design, user-defined features (UDF) and parts library that reflects the product parts information is playing an increasingly important role. A UDF management function and a parts library system was provided in most of the dominate CAD platform, but in using the UDF management function, UDF definition steps are dispersed, the definition process is complex and cumbersome, and the UDF library classification can not achieve the UDF sharing, parts library system still had poor scalability and commonality problems. The above problems had seriously affected the efficiency of product design, the capacity of the market responsiveness was reduced.This paper researches the UDF and parts library in semantic feature modeling from two aspects, theory and system design. In order to resolve the problems of the UDF management, through researching on user-defined feature class, the defining process of user-defined feature has four steps, namely defining feature shape, defining feature property, defining feature constraint and defining feature interface, and defining content in each step was classified in detail, thus rapid definition about user-defined feature was achieved; At the same time, a classification model of user-defined feature library was proposed based on directed acyclic graph. In the model, classification and sharing of feature was implemented through a directed acyclic graph formed by attaching feature information as common sub-node into classification tree, and the model was stored by neutral XML document in order to improve the portability of model. the method of model founded was proposed. A parts library system based on UDF was proposed in order to improve the parts library system scalability and commonality, the UDF technology, parameterization technology and database technology were applied to the parts library system design, the management of the UDF template was achieved by using the UDF management module and interface from different CAD platforms, unlimited categories and data sharing of the parts was implemented by designing the database, and the processes of the parts entering into the library and invoking from the library were presented based the data structure. This study results have been applied to HUST-CAIDS (Computer Aided Industrial Design System developed by Harbin University of Science and Technology), practical application shows that the capacity of the UDF management was improved effectively in a CAD platform, scalability and commonality of parts library system were enhanced, design efficiency about product was improved extremely.