Development of a framework for a set of computer-aided tools for tolerance analysis

This research is part of a large on-going project aiming to develop a new mathematical model for geometric dimensioning and tolerancing (GD&T) to support tolerance specification, validation, analysis, and allocation. The focus of this dissertation is on investigating current tolerance analysis methods and developing a set of computer-aided tolerance analysis tools, i.e. automated tolerance charting, 3D feature variation, and T-Maps based tolerance analyses.;First, this research has investigated the representation and automatic creation of the global model, which is a superset constraint-tolerance-feature graph based GD&T model. This analysis model contains semantic information related to geometry, constraints, tolerances, and assembly hierarchy based on degrees-of-freedom and tolerance analysis model. The model can be used for validation of dimensioning and tolerancing schemes, as well as, all types of tolerance analysis.;Second, this research has investigated the manual tolerance chart based method and proposed a method to automate it. The popular manual technique is time-consuming and error-prone, and this research has proposed a method to automate it.;Third, this research has investigated the 3D feature variation based tolerance analysis, in an attempt to perform tolerance analysis by simulating 3D geometric variations as defined in the GD&T standards. Various commercial computer-aided tolerancing packages utilize this approach, but they are only partially successful, in terms of the consistency with the GD&T standards. This work has looked into related research issues and improved the status of the art in two aspects: model creation and variation algorithms.;Fourth, this research has done the implementation work related to the T-Maps based tolerance analysis method. This includes development of modeling functions of the different T-Maps, development of a generic and robust Minkowski Sum framework for Minkowski sum operations, display of higher dimensional T-Maps, and some case studies for T-Maps based worst-case analysis.;Finally, this research has conducted a comparative study of these tolerance analysis methods (i.e. charting, 3D parametric and T-Maps based), first from a theoretical point of view, and then through some case studies by using the tools that have been developed. The purpose of the comparison is to offer recommendations to the designers about the suitability of these methods for different types of problems.