In the area of design, our focus has been on (i) effective information management for Computer-Aided Design (CAD). Design by features is a novel approach for the high-level modeling of objects that allows for sharing of information between activities such as design and manufacturing process planning; (ii) reconfigurable fixture design for thin-walled objects; and, (iii) life-cycle analysis for remanufactured products. Our research on the first topic has been dealing with a specific issue in this area, namely the development of a generic form-feature extraction and coding framework for objects with planar surfaces.
A form feature is defined as a geometric formation on an object which can be associated with design/manufacturing information. There exists two main approaches to the identification of form-feature information from a CAD model. The first approach, feature recognition, requires a pre-defined instance of the form feature to be recognized. The second approach,feature-based modeling, incorporates the form-feature information directly into the part model during the design stage by using a set of pre-defined features. Therefore, in both cases, the identification of form features present in a CAD model is limited by the size and variety of a pre-defined set.
In the area of intelligent fixturing, we have developed a novel reconfigurable modular system for the fixturing of thin-walled, flexible objects subject to a discrete number of point forces. During the mechanical design phase of the fixture, a conscientious effort was made to develop a robust and low-cost system. The primary components of the fixture are: a baseplate, support locators and clamps. A novel tiltable support-surface design, through which the height of the surface can be maintained constant, is used for the locators and the clamps. A fixture reconfiguration method based on finite-element-analysis is to place these locators, underneath the object, as an optimal support wall. Potential surface deflections due to external forces are minimized during the optimization process.
Remanufacture offers significant economic and ecological advantages over other end-of-life options. There exists a need for integrating remanufacturing considerations with traditional design assessments in order to make better tradeoffs between complex sets of design objectives. In this context, the evaluation of life cycle cost for systems undergoing remanufacture was the objective of our work.
A novel repairable-system reliability model that allows system modifications was developed to describe systems undergoing remanufacture. Explicit expressions of the relationships between remanufacture and life cycle cost were obtained based on the indices of the reliability model; The stochastic behavior of the reliability model was investigated to facilitate life-cycle cost estimation. The reliability model was further modified to accommodate population size changes in the replacement process. The effects of two types of disturbances, pulse or continuous, on the replacement rate behavior were studied.