9500126 Yang This research integrates dynamic multistate reliability model and quality loss analysis in order to describe the product performance degradation as a function of time. In this modeling approach the product performance level is expressed as the function of product design parameters and environmental factors at any given time. A quality loss function which measures the product performance level over a time period will be defined. The model and loss function then lead to reliability-driven product parameter design, product performance evaluation, reliability-driven product tolerance design, and reliability and robust design integration. The research is partially built upon work in collaboration with the Ford Motor Company on reliability-base motor vehicle system evaporative emission, using evaporative emission as a typical performance degradation problem. Collaboration with Ford Motor Company allows the results of this research to be validated by combining the theoretical research with a practical reliability-based study of a motor vehicle fuel system's evaporative emission for 1995 and subsequent model years. This research will contribute to motor vehicle manufacturers' ability to meet new standards for evaporative emission governed by the Clean Air Act and set by the EPA and the California Air Resource Board. It will also develop techniques for reliability-driven product design and suggest robust design integration strategies that can be used more generally.
