ABSTRACT
When evaluating or predicting dependability of products in reliability engineering practice, we may face one kind of problems where product is repairable and mission time is flexible, i.e. repairs are allowed during mission process only if the accumulated delayed time is less than or equal to a specified time duration. The analytic solutions to this kind of problems are difficult or impossible to be derived. To solve this kind of problems, the relevant terminologies are listed and analyzed, firstly. Then, the occurrence processes of the probabilistic events corresponding to mission success or failure are analyzed. After this, a numerical method based on Monte Carlo simulation is proposed to compute dependability of repairable items when mission time is flexible. Finally, two examples are presented. The first one illustrates the use of the proposed method to assess or to predict dependability of an exponential distributed item. The second one shows the use of the method to compare two products in the dependability when mission time is specified, but repairs are allowed in the limited accumulated time during mission. Although, for simplicity, products in the two examples are assumed to follow exponential distributions, the method is available to any items with one or more failure mechanisms that follow the common distributions in reliability field, such as exponential distribution, normal distribution, log-normal distribution and Weibull distribution.
