STEP AP 242 file-based automatic tolerance analysis of mechanical assembly using unified Jacobian Torsor Model and direct linearization method

This work presents the approach and algorithms to develop a smart computer-aided tolerance analysis system that is capable of performing Unified Jacobian Torsor Model (UJTM) and Direct Linearization Method (DLM) based deterministic tolerance analysis on mechanical assemblies using the STEP AP 242 file data generated from the assembly 3D CAD model. The smart tolerance analysis system tested on two different CAD packages can automatically extract the B-rep data, tolerance data from the STEP AP 242 file and find the mating surface information to perform the tolerance analysis. The location of the STEP AP 242 file is given as the input into the developed smart system, and the final output is the deterministic variation in the functional requirement and the plot showing the percentage contribution of tolerance to the variation in functional requirement of the mechanical assembly. The capability of the developed smart system is validated against the two mechanical assembly case studies, and the results computed by the developed system are an exact match with the tolerance values calculated manually.