Integrated Quality and Reliability Methodology for Complex Systems Subject to Multiple Failure Processes.

摘要

Quality and reliability of complex products and systems are becoming increasingly important because of the intense global competition and higher customer expectations. Traditional approaches are inadequate or inappropriate to obtain globally optimized policies because quality and reliability related policies over the product life cycle, such as burn-in policy, quality inspection policy and preventive maintenance policy, are often optimized separately. This research develops new integrated quality and reliability models and analysis tools that can be applied to improve the overall performance for various complex systems, especially some novel technologies, such as micro-electro-mechanical systems (MEMS).;Mathematical methodologies for single-component systems subject to one failure mode are first proposed in order to optimize burn-in, quality inspection and maintenance policies simultaneously. Case studies of microengines in MEMS devices and light displays are provided to illustrate this integrated optimization method. Meanwhile for various linear and non-linear degradation models, conditional reliability functions and truncated failure time distributions considering the impacts of burn-in and quality inspection at manufacturing phase are developed. Case study of ultra-thin gate oxides is used to illustrate the logistic degradation path model.;Furthermore, the reliability model is derived and the maintenance policy is optimized for systems that experience two dependent competing failure processes, i.e., wear degradation and structure fracture caused by random shocks in operating environments. This mathematical framework has been successfully implemented on MEMS devices in extreme environments (e.g., shock, vibration). For multi-component systems, based on the reliability analysis of systems with independent or dependent degrading components, new importance measures are created to provide timely feedback on the relative proximity of components to an impending failure.;This new integrated quality and reliability methodology offers manufacturers new perspectives to further enhance the level of quality and reliability of their products as well as to reduce the total cost rate in order to gain competitive advantages over the long term. The reliability models and analytical tools developed for multiple failure processes and complex multi-component systems can be readily applied to a wide range of complex systems.