Extracting common design patterns from a set of solid models

In mechanical design, designers often consciously or unconsciously create some engineering-rich local shape structures repeatedly in parts by combining regular design features. Identification of these local structures with high appearance frequencies is helpful for design-rule mining, design feature library customization and model data compression. In this paper, an approach is developed for extracting common local structures as design patterns from a set of B-rep models. Here, B-rep models are first transformed into a representation of Volume Relational Graphs (VRG), in which each volume is generated from a face shell in a boundary partition of a solid along specially selected cutting loops. Then, two kinds of code, Face Shape Code (FSC) and Face Location Code (FLC), are introduced to describe shapes of the volumes. After this, based on equality of the codes between volumes, isomorphic subgraphs among VRGs are identified as design patterns with a greedy search method, whose objective is to find precise expressions in the patterns for the original solid models.