Research On Local Feature Reuse Of 3D CAD Models

With the upgradating of product demands and the rapid development of computer-aided technology,3D CAD models tend to be complicated and diversified,and the number of models is growing explosively.It becomes one of research focuses that how to reuse existing 3D models effectively to improve the efficiency of product design and development.In this dissertation,the method of reusing local features of 3D CAD models is studied by rebuilding local features of part models and replacing parts of assembly models.The parent-child relationship between features is obtained from 3D CAD models.Then feature tree is used to describe the parent-child relationship of features in part model,and component adjacency graph is used to describe the parent-child relationship of features in assembly model.The auxiliary shape features in the part model are preprocessed.Local feature reuse of part models is studied based on oriented bounding box.This local reuse method is implemented between two part models.Firstly,principal component analysis is used to obtain oriented bounding boxes of reusable local features in the reference model and local features to be replaced in the current design model.By traversing geometric dimensions of reusable local features and distinguishing directional relations between geometric elements and principal axes of oriented bounding box,shape dimensions are changed according to ratio of edges of two oriented bounding boxes.Then,the sketch plane is searched from all the faces of parent feature to rebuild sub-features.Finally,modified reusable features are rebuilt on the original position of local features to be replaced in the current design model.Local reuse method in assembly model is studied based on part replacement from the reference model to the current design model.Attribute information of assembly features is acquired,such as types and parameters of assembly constraints.And assembly constraint types and geometric element types are numbered to realize assembly feature information coding.Based on the correspondence of geometric elements in assembly features,parts are replaced between two assembly models by adding new assembly features and modifying relevant attribute information.Based on C++ language and SolidWorks API,the program is designed to generate dynamic link library files(.dll),which could be loaded into SolidWorks in the form of plug-ins.Experiments show that the method can effectively reuse local features of 3D CAD models.