Computer-aided representation and analysis of geometric tolerances
Abstract
Presently available CAD data models have no problem in handling the basic shape design of an object as required but they are not properly manufacturing-oriented. It is not possible to represent the dimensioning and tolerancing information or other technological information (such as material data, the surface roughness and accuracy data, feature information, etc.). In this thesis, we shall discuss the requirements of a new CAD data model and the suitability of adopting a feature-based representation scheme based on the hybrid CSG/B-Rep data structure. A front-end scheme necessary for interfacing the tolerance module with the solid model has been developed. This includes the development of (i) an efficient user interfacing system for inputing tolerance information, (ii) a suitable tolerance data module (to be attached to the solid model), and (iii) an information retrieval system from the stored database for tolerance analysis. Tolerance analysis has been carried out on two levels: individual part level and assembly level. Problems related to syntax and semantics of tolerance representation, consistency and validity of the specification (including the redundancy checking) are addressed in the part level analysis while the checking for the required mating conditions between different assembled parts is performed in the assembly level analysis. To facilitate the tolerance analysis in assembly, a generic assembly database is designed to encode explicit mating conditions between the parts for the establishment of functional relationships between the parts of the assembly. This database also helps in planning the assembly sequence.
Degree
Ph.D.
Advisors
Liu, Purdue University.
Subject Area
Industrial engineering
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