A tolerance representation model for conceptual design

Conceptual design is crucial in new product development with great impact on the downstream design process. However, current engineering practices often involve tolerancing in the detail design phase not in the conceptual design phase. This paper presents a methodology where the design tolerancing is considered in the conceptual design phase to ensure the feasibility of conceptual-structure design. The essence of tolerance design is the conversion of product functional requirements to functional tolerances. The characteristic and mating surfaces called key features (KFs) with profound influences on the product requirements are developed. Then the ATTRIB class offered by ACIS geometrical kernel is used to establish the hierarchical structure of all the necessary tolerance classes. The hierarchical tolerance representation model is constructed based on the Topologically and Technologically Related Surfaces (FTTRS). Therefore, the entire framework of the functional tolerance design is developed. The conceptual design-oriented tolerance information model effectively integrates the tolerance design and conceptual design.