威布尔分布下系统全寿命周期成本建模与决策

Modeling and decision-making of system lifecycle costs under Weibull distribution

系统可靠性设计优化与经济性密切相连.针对部件寿命服从威布尔分布的同质部件组成的系统,引入经济的预防性成组维修策略,构建设计费用、制造费用和维修费用函数,从而建立可靠性约束下的系统全寿命周期成本的优化模型.通过与无预防性维修下系统全寿命周期成本模型的比较分析,效用曲线充分验证所建优化模型的经济性和有效性.接着,给出包括系统全寿命周期成本、部件可靠性设计水平和预防性成组维修频率在内的系统设计均衡区间的决策方法.最后,以某大型科学装置的开关系统为例,说明该方法在工程应用上的实效性,为系统工程师开展可靠性设计优化提供系统的思路和方法.

System design optimization based on reliability is closely linked with economy. Under the conditions that the life of components follows Weibull distribution and group strategy is applied to preventive maintenance, design cost function, manufacturing cost function and maintenance cost function are presented respectively for a multi-unit system which is composed of identical units. And then, a lifecycle costs optimization model under reliability constraints is given. Reliability design value and group preventive maintenance policy in operation phase are comprehensively analyzed by the model. A decision method of equilibrium area for system design is put forward, which includes balanced lifecycle costs, required design reliability and group preventive maintenance period. Finally, an example analysis of switching systems of a large-scale scientific facility is shown to demonstrate its effectiveness and applicability. In the case, curves between optimal lifecycle costs and required reliability design value are obtained. The curve of optimal lifecycle costs with group preventive maintenance strategy is compared with no group preventive strategy, and the intrinsic relationship of reliability-based design, maintenance strategy and the optimal lifecycle costs are revealed by a utility curve altogether. The proposed decision method is helpful to get a new equilibrium area when key parameters are changed by technological advance. Therefore, it is of great significance for system engineers to carry out reliability-based design optimization by these provided solutions and methods.