| Summary: | 博士 === 國立交通大學 === 工業工程與管理學系 === 99 === Reliability allocation is one of the most important factors to consider when determining the reliability and competitiveness of a product. The feasibility-of-objectives (FOO) technique has become the current standard for assessing reliability designs for military mechanical-electrical systems, whereas the average weighting allocation method is widely used for commercial applications. However, the conventional reliability allocation methods have six fundamental problems. The first problem is the measurement scale, while the second problem is that the system allocation factors are unequal weighted to one another, the third problem is most reliability allocations methods often neglect many important features, such as maintainability and risk issues. The forth problem is that they do not consider indirect relations between subsystems or components; the fifth problem is they do not consider predicted failure rate in the apportionment process and finally the sixth problem is in designing or modifying a complex system, where the technological or financial constraints might dictate the maximum achievable reliability. To address these issues, this study proposes three reliability allocation methods. Depending upon the operational environment and data required on design process, if data not available, the maximal entropy ordered weighted averaging (ME-OWA) method is suggested, which efficiently resolves the shortcomings of the FOO technique and the average weighting allocation method. If cost is highest concern and data is available, such as predicted failure rate, predicted unit cost etc., the cost-based situational maximal entropy ordered weighted averaging (SME-OWA) approach is suggested that associates the required cost, to a particular technology level, of a predicted failure rate of subsystems. If the risk issue is highest concern and we can get FMEA data before the design process, the combined failure mode and effects analysis (FMEA) and decision-making trial and evaluation laboratory (DEMATEL) technique is suggested, which considers severity of failure, occurrence of a failure, and detection of a cause of failure in reliability design. This study evaluates reliability allocation in the context of a fighter aircraft airborne radar system, landing gear system and engine data acquisition unit (EDAU). The results from these three comparisons show that the proposed methods are both accurate and flexible for actual commercial application.
|
|---|
