Design Feature Reconstruction For 3D Geometric Boundary Models

Feature based modeling has become the main way of current product modeling.As a carrier for designers to express their design intentions,design features contain specific engineering semantics.Product design using design features can reduce repetitive work and improve design efficiency.However,in the design practice,there are a large number of digital models without design features,which result in difficulties of modifying these models and unable to extract their design features for reuse.Therefore,it is of great theoretical significance and practical application value to find design features with certain engineering semantics from B-rep model and to reconstruct them.Boundary segmentation of solid models is the geometric foundation to reconstruct design features.This thesis analyzes the shape evolution of the model in the modeling process,simulates the designer's modeling thinking,and decomposes the B-rep model into a set of design features.Firstly,the boundary information of a model is extracted,and then the B-rep model is represented in a form of feature vertex adjacent graphs by making full use of the topological relations between vertices.In order to realize the boundary segmentation of the solid model,a series of segmentation loops are obtained by searching the Boolean segment loops in the feature vertex adjacency graph.In this process,the virtual topology is introduced for the missing feature boundary caused by the shape evolution in the modeling process,by deleting or adding nodes and arc edges in the feature vertex adjacency graph and adjusting the connection relationship between the nodes,the topological structure of the model is virtually changed to restore the complete boundary of the feature,avoiding changes to the real structure of the model.Finally,formulate the segmentation order,select the appropriate segmentation loop as the segmentation tool to segment the B-rep model into a set of segmentation faces corresponding to different design features,and close the segmentation surfaces by extending the relevant segmentation surfaces to construct the design features.For the above theories and methods,using object-oriented programming methods and the secondary development interface provided by SolidWorks a feature reconstruction module has been developed.Case study and experiment of reconstruct design features show the effectiveness of this method.