Optimal Opportunistic Maintenance Policies of k-out-of-n Systems

In this article, the reliability model and the opportunistic maintenance optimization model are formulated for the preset self-repairing mechanism which is artificially designed and applied to many engineering systems. The preset self-repairing mechanism is first introduced into the reliability model, and a series system consisting of two units is built to describe the proposed model. One unit in the system is subject to external shocks and has the preset self-repairing mechanism, the other does not have the recovery mechanism and its lifetime distribution follows exponential distribution. For the system, the analytical expression of reliability is derived, and a maintenance optimization model taking the long-run average cost per unit time as objective function is established. The decision parameters of the maintenance policy are preventive and opportunistic degradation levels. Besides, a preventive maintenance policy is proposed for comparison with the opportunistic maintenance policy. Finally, the numerical examples are provided to obtain the optimal decision parameters and demonstrate the effectiveness of opportunistic maintenance policies.

Download Full-text

Availability analysis and maintenance optimization for multiple failure mode systems considering imperfect repair

Proceedings of the Institution of Mechanical Engineers Part O Journal of Risk and Reliability ◽

10.1177/1748006x211012792 ◽

2021 ◽

pp. 1748006X2110127

Author(s):

Qingan Qiu ◽

Baoliang Liu ◽

Cong Lin ◽

Jingjing Wang

Keyword(s):

Failure Modes ◽

Maintenance Cost ◽

Imperfect Maintenance ◽

Maintenance Policy ◽

Cost Rate ◽

Availability Analysis ◽

Long Run ◽

Optimal Maintenance ◽

Maintenance Policies ◽

Periodic Inspections

This paper studies the availability and optimal maintenance policies for systems subject to competing failure modes under continuous and periodic inspections. The repair time distribution and maintenance cost are both dependent on the failure modes. We investigate the instantaneous availability and the steady state availability of the system maintained through several imperfect repairs before a replacement is allowed. Analytical expressions for system availability under continuous and periodic inspections are derived respectively. The availability models are then utilized to obtain the optimal inspection and imperfect maintenance policy that minimizes the average long-run cost rate. A numerical example for Remote Power Feeding System is presented to demonstrate the application of the developed approach.

Download Full-text

Fleet Resilience: Evaluating Maintenance Strategies in Critical Equipment

Applied Sciences ◽

10.3390/app11010038 ◽

2020 ◽

Vol 11 (1) ◽

pp. 38

Author(s):

Orlando Durán ◽

Javier Aguilar ◽

Andrea Capaldo ◽

Adolfo Arata

Keyword(s):

Application Study ◽

System Availability ◽

Maintenance Strategies ◽

Resilience Index ◽

Reliability Block Diagrams ◽

Maintenance Policies ◽

Definition Of ◽

The Impact ◽

Important System ◽

Intrinsic Characteristic

Resilience is an intrinsic characteristic of systems. Through it, the capacity of a system to react to the existence of disruptive events is expressed. A series of metrics to represent systems’ resilience have been proposed, however, only one indicator relates the availability of the system to this characteristic. With such a metric, it is possible to relate the topological aspects of a system and the resources available in order to be able to promptly respond to the loss of performance as a result of unexpected events. This work proposes the adaptation and application of such a resilience index to assess the influence of different maintenance strategies and topologies in fleets’ resilience. In addition, an application study considering an actual mining fleet is provided. A set of critical assets was identified and represented using reliability block diagrams. Monte Carlo simulation experiments were conducted and the system availability data were extracted. Resilience indexes were obtained in order to carry out the definition of the best maintenance policies in critical equipment and the assessment of the impact of modifying system redundancies. The main results of this work lead to the overall conclusion that redundancy is an important system attribute in order to improve resiliency along time.

Download Full-text

Multi-Level opportunistic Maintenance optimization of Offshore Wind Turbines Based on Rolling Horizon Approach

2020 IEEE International Conference on Mechatronics and Automation (ICMA) ◽

10.1109/icma49215.2020.9233524 ◽

2020 ◽

Author(s):

Hanrong Luo ◽

Chun Su

Keyword(s):

Wind Turbines ◽

Offshore Wind ◽

Maintenance Optimization ◽

Rolling Horizon ◽

Opportunistic Maintenance ◽

Offshore Wind Turbines ◽

Multi Level

Download Full-text

Integrating Modelling of Maintenance Policies within a Stochastic Hybrid Automaton Framework of Dynamic Reliability

Applied Sciences ◽

10.3390/app11052300 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2300

Author(s):

Simone Arena ◽

Irene Roda ◽

Ferdinando Chiacchio

Keyword(s):

Model Systems ◽

Mitigation Measures ◽

Repairable Systems ◽

Maintenance Policy ◽

Hybrid Automaton ◽

Dynamic Reliability ◽

Software Model ◽

Maintenance Policies ◽

Mathematical Techniques ◽

Continuous And Discrete Variables

The dependability assessment is a crucial activity for determining the availability, safety and maintainability of a system and establishing the best mitigation measures to prevent serious flaws and process interruptions. One of the most promising methodologies for the analysis of complex systems is Dynamic Reliability (also known as DPRA) with models that define explicitly the interactions between components and variables. Among the mathematical techniques of DPRA, Stochastic Hybrid Automaton (SHA) has been used to model systems characterized by continuous and discrete variables. Recently, a DPRA-oriented SHA modelling formalism, known as Stochastic Hybrid Fault Tree Automaton (SHyFTA), has been formalized together with a software library (SHyFTOO) that simplifies the resolution of complex models. At the state of the art, SHyFTOO allows analyzing the dependability of multistate repairable systems characterized by a reactive maintenance policy. Exploiting the flexibility of SHyFTA, this paper aims to extend the tools’ functionalities to other well-known maintenance policies. To achieve this goal, the main features of the preventive, risk-based and condition-based maintenance policies will be analyzed and used to design a software model to integrate into the SHyFTOO. Finally, a case study to test and compare the results of the different maintenance policies will be illustrated.

Download Full-text