考虑备件及维修周转的并串混联系统可用度模型

给出了综合考虑系统结构、库存备件量和故障件维修周转等因素影响下的系统可用度计算模型。将由并串混联系统和备件组成的广义系统按功能划分为工作系统与库存系统两个子系统,通过引入备件平均到达率反映库存系统对工作系统的影响,并据此分别建立备件充足与缺货时的工作系统状态转移关系。利用二项分布表征期望备件短缺数的概率分布函数以计算库存系统备件的缺货概率,进而根据全概率公式计算得到系统可用度。示例表明:所提模型针对单部件串联系统所得结果比已有模型更为精确;其次,在库存备件量及维修周转时间的影响下,多部件子系统串联时并不比单部件串联时的可用度高,且可用度曲线随着库存量的增加并不是严格单调递增的凸曲线。

Availability modeling of parallel-series system under influence ofspare parts and maintenance turnover

Availability modeling of parallel-series system is proposed with the consideration of system structure, the number of spare parts, and maintenance turnover. Therefore, the whole system composed of parallel series system and spare parts is divided into operation system and inventory system according to its function. By introducing the average rate of arrival of spare parts to reflect the influence of the inventory system on the operation system, state transfer relationship of the operation system is given under the conditions that spare parts are sufficient and insufficient. And the binomial distribution is used as the probability distribution function of expected backorder to calculate spares shortage probability’s, further to calculate system availability with the formula of full probability. Ultimately, the example shows that, firstly, aiming at series system, the results of the proposed model is better than those of the former model; secondly, under the influence of the number of spare parts and maintenance turnover, availability of multi 1/N system is not higher than series system and the availability curve is not strictly monotonically increasing convex curve with the increase of inventory.