Mission Availability Modeling Methods For Repairable Fleet Under Timing Constraints

In recent years, large devices included multiple identical or similar single systems extensive uses in the practice with the increasing engineering demand. The complex device composed of multiple identical or similar systems perform specific tasks independently(hereinafter referred to as fleet), can satisfy the functional requirement easier. The complex structure and high cost in the process of operation and maintenance increase the difficulty of the reliability management.Effectively reliability management of fleet is very important that it will greatly reduce the frequency of failures and the operating costs of fleet. Availability assess is the important part of reliability management to repairable fleet.Based on the existing research about one uint system availability, this thesis study the modeling method of fleet mission availability considering the constraints of operating time and maintenance time. The study extend the research range of system availability and closely combine theory with practice. The main contributions and innovative outcome of this thesis are smmarized as follows:(1) Development of modeling method and algorithm of repairable fleet availability under exponential distribution;Exponential distribution is the most common distribution in reliability enginerring. Failures aroused from incidental and random event regular obey exponential distribution. This part give the modeling methed of fleet availability with the limited operating time and maintenance time. Frist, analyze the operating time and maintenance time of system and fleet separately to get operating and maintenance time distribution of fleet, and then establish it’s probability model of mission availability. For k/N(G) fleet, propose a hybrid approach that combine simulation and analytical calculations to estimate it’s availability.(2) Development of modeling method and algorithm of repairable fleet mission availability under weibull distribution;Operating time disrtribution of large-scale complicated system generally obey to weibull distribution according to the statistical result of engineering application. Based on the method of(1), develop the modeling method of mission availability of N/N(G) and k/N(G) fleet when the operating time of system in the fleet obey to weibull distribution, maintenance time obey to exponential distribution.(3)Describe the curves of mission availability as one variable among operating time and maintenance time limit varies;To prove the effectiveness of the algorithm, detailed steps of mission availability modeling method of a specific device is indicated. What’s more, study the relationships between time constrains and mission availability of the device when the system exponential distribution and weibull distribution respectively to get the curves of mission availability and time constraints. The result of the thesis provide method and gist to support system manager to formulate the reliability design at the design stage and operation and maintenance plans at the service stage.