复杂退化系统的组合维修策略优化

由于现有视情维修研究中没有考虑定期维护的影响,无法准确反映定期维护下的系统性能退化规律,因而不利于合理制定定期维护与视情维修组合的维修策略。针对该问题,重点开展了该组合维修策略下的性能退化建模与维修决策研究。通过结合组合维修策略下的性能退化特点,从失效机理出发,利用复合Poisson过程建立了性能退化模型,并通过退化强度函数描述了仅恢复累积性能退化量而不改变性能退化规律的维修效果。同时,分析了该条件下的可靠度函数,说明了其具有阶梯型变化和突变性的特性。基于性能退化模型,建立了长期运行条件下以费用率最低为目标、失效风险为约束的组合维修决策优化模型,并求解确定了最优维护周期和预防性维修阈值。通过数值分析,描述了费用率随维修策略值变化的规律,说明了优化解的存在性。同时,通过与系统自身寿命规律比较,说明采用该优化模型,可以有效地延长系统的使用时间,实时控制失效概率,确保其具有较高的安全等级,进而有效地降低维修费用。

Optimal combination maintenance strategy of deteriorating complex system

As the existing condition-based maintenance strategy does not consider the effect of scheduled servicing, the performance deteriorating law cannot be reflected exactly, which is not helpful to give a rational maintenance strategy which combines the scheduled servicing with condition-based maintenance. Aimed at this problem, the performance deteriorating rule and maintenance optimization model under combination maintenance strategy are analyzed deeply. The performance deteriorating model is established by composite Poisson process based on the deteriorating characteristic from the failure mechanism. It describes the maintenance effect of servicing by using intensity function which only restores the cumulative deteriorating values and doesn''t have impact on the deteriorating law. And the reliability is also analyzed to obtain the peculiarity of ladder decrease and saltation. On the basis of it, the optimization model is given to determine the optimal servicing period and preventive maintenance thresholds, with an objective to minimize the system cost rate and build a constraint to failure risk. The numerical example demonstrates the cost rate rule with different maintenance strategy values. So the existence of optimal cost rate is proved. Compared with the lifetime, it also shows that the optimal maintenance strategy values can prolong system operational time and control the failure risk. So the system can have high safety grade and a great decrease on the maintenance cost.