Step Based Geometric and Topological Similarity Assessment of Mechanical Parts

In this paper, an approach has been developed to assess geometric and topological similarity between 3D mechanical parts using their face-edge relation matrices. The approach relies on the STEP (Standard for the Exchange of Product Data Model) graphic standard to obtain the geometric and topological data belonging to parts designed in a CAD system. The CAD model of any part is automatically translated into a STEP file and entities represented in the STEP file of it are mapped into face-edge relation matrix. Face-edge relation matrix is a square matrix and sized according to number of faces on a part. In the similarity assessment stage, the closest matrix in the database corresponding to matrix of the new part is retrieved and matched as matrix of the candidate part. Similarity factor between the new and candidate parts is calculated with respect to the matched faces and total faces in both matrices. Similarity assessment is useful for many CAD/CAM applications such as especially variant process planning, cost estimation and group technology. The algorithm has been applied to some real parts to demonstrate its efficiency and capability.