Abstract
Due to the increasing complexity of modern engineering systems, availability is more and more emphasized when systems are used. In order to develop availability sound products, this paper presents a supporting method to evaluate the reliability and maintainability of the feasible solution in the early design phase. The evaluation is implemented based on some scaling factors that are determined according to the differences of the involved engineering activities between the feasible solution and an existing system. The engineering activities are constructed from three aspects: the complexity of product itself, the maturity of product in production and the related factors of product in use. Once the scaling factors are decided, the mean time between failure and the mean time to repair of a design are then estimated according to the data in failure and in maintenance of the known system. No sooner than the mean time between failure and the mean time to repair of a design are established, its availability in future use can also be calculated. Subsequently, the information is considered with the total cost estimation of the system for selecting the optimal one among the feasible solutions. Plausibly, the availability sound designs would be more easily achieved as well as the specified availability goal being further obtained by the design trade-off analysis.
Acknowledgements
This work was supported by a grant from the National Science Council under contract number NSC 91-2212-E-237-001. The authors would like to thank the reviewers for their valuable suggestions.