Joint optimization of maintenance policy and inspection interval for a multi-unit series system using proportional hazards model

Abstract

Unlike the previous maintenance models of multi-unit systems which considered condition-based maintenance (CBM) or age information separately, we propose a novel optimization model which is characterized by a combination of CBM and age information using proportional hazards model. The preventive maintenance is applied for the main two units, where one unit is the core part of the system and subject to CM, and only the age information for the second main unit is available. Also, the other units are adjusted or replaced each time when the system is maintained. The objective is to find an optimal opportunistic maintenance policy minimizing the long-run expected average cost per unit time. The problem is formulated and solved in the semi-Markov decision process framework. The formula for the mean residual life of the system is derived, which is an important statistic in practical applications. A practical example of a multi-unit system from a mining company is provided, and a comparison with other policies shows an outstanding performance of the new model and the control policy proposed in this paper.

Mathematical optimization models for long-term maintenance scheduling of wind power systems

“…Jafari et al [10] propose a joint optimization of the maintenance policy and the inspection interval for a multi-unit series system. The authors develop a model and algorithm which are used to determine a maintenance policy that minimizes the maintenance cost for a multi-component system; in the system studied, one unit is subject to condition monitoring, while for the other unit, only age information is available and which has a general distribution.…”

“…where G PM spT (y, z) is defined in (10). Then, if there is a component failure at time v ∈ [0, T − γ CM j ], the component should be replaced only if it holds that…”

Predictive maintenance for aircraft components using proportional hazard models

“…PHM models have been employed succesfully in research before [18][19][20][21][22][23]; for an in-depth review of PHM, the reader is referred to the papers of Si et al [24] and Kumar and Klefsjö [25]. The identification of covariates that may affect reliability is discussed in more detail in Kalbfleisch and Prentice [26] and Ascher and Feingold [27], respectively.…”

Optimal scheduling of the next preventive maintenance activity for a wind farm

“…There is a multitude of papers devoted to the optimal PM scheduling for multi-component systems; see Werbińska-Wojciechowska (2019). The article Jafari et al (2018) proposes a joint optimization of the maintenance policy and the inspection interval for a multi-unit series system with economic dependence. It develops an algorithm aiming Q.…”