Characterization and representation of functional requirements and functional tolerancing for concurrent design and manufacturing

The proposed dissertation research is designed to investigate two issues that are directly related to the concurrent design and manufacturing of mechanical products and systems. The focus is on understanding the functional structure of modern mechanical products and on modeling their required functions so as to support the various activities in their design and manufacturing.;The characterization of the functional requirements of both mechanical components and systems has been studied in this dissertation research. The hierarchy analysis, the decomposition, and the dependence check of the functional requirements are used as three major issues in the characterization process. To represent a group of functional requirements, a functional structure and a descriptive model which includes functional intent, characteristics, and target value or ideal state are proposed. The representation scheme can be implemented along with the design model of a product to provide sufficient information for downstream product activities.;To support the subsequent production activities, based on the understanding of the various functional requirements, an approach of tolerancing for function is presented. The tolerancing for function approach attempts to determine the possible tolerance specifications for a product directly according to its functional requirements and their allowable variations. Based on the proposed tolerancing for function approach, a framework for functional tolerancing is proposed which can be implemented in a computer-integrated design and manufacturing environment. The framework includes four inter-related modules: identification, transformation, tolerancing, and specification modules.;The proposed functional framework provides a basis for the characterization and representation of the functional requirements in mechanical design. It will also provide a basis for integrating design intent into the product cycle so that higher level of decision making and complex reasoning for the determination of optimum product design and process planning become possible. The proposed tolerancing for function approach can be used to support the subsequent production activities, and establish a foundation for continuing research on automatic tolerancing. By using the proposed functional tolerancing approach, the current practice of tolerance representation and specification can be extended and applied to the products that are sophisticated in function and/or complicated in geometry.