Optimal inspection of a complex system subject to periodic and opportunistic inspections and preventive replacements

• Published in: European journal of operational research Vol. 220; no. 3; pp. 649 - 660
• Main Authors: Taghipour, Sharareh, Banjevic, Dragan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2012; Elsevier; Elsevier Sequoia S.A
• Subjects: Applied sciences; Complex systems; Exact sciences and technology; Expected values; Failure; Hard failure; Infusion; Inspection; Inspections; Maintenance; Mathematical analysis; Mathematical models; Mathematical programming; Operational research and scientific management; Operational research. Management science; Opportunistic inspection; Optimization; Optimization algorithms; Periodic inspection; Preventive maintenance; Preventive replacement; Pumps; Soft failure; Studies; Hard failure; Maintenance; Periodic inspection; Opportunistic inspection; Soft failure; Preventive replacement; Replacement problem; Complex system; Periodicity; Replacement; Failures; Modeling; Preventive maintenance; Optimization; Pump; Recursive method; Objective function; Hospital; Repair; Age
• ISSN: 0377-2217; 1872-6860
• DOI: 10.1016/j.ejor.2012.02.002

► We model a system with revealed and hidden failures. ► System undergoes periodic and opportunistic inspections. ► Two mathematical models are developed to calculate the total excepted cost. ► The periodic inspection interval is optimized. This paper proposes two optimization models for the periodic inspection of a system with “hard-type” and “soft-type” components. Given that the failures of hard-type components are self-announcing, the component is instantly repaired or replaced, but the failures of soft-type components can only be detected at inspections. A system can operate with a soft failure, but its performance may be reduced. Although a system may be periodically inspected, a hard failure creates an opportunity for additional inspection (opportunistic inspection) of all soft-type components. Two optimization models are discussed in the paper. In the first, soft-type components undergo both periodic and opportunistic inspections to detect possible failures. In the second, hard-type components undergo periodic inspections and are preventively replaced depending on their condition at inspection. Soft-type and hard-type components are either minimally repaired or replaced when they fail. Minimal repair or replacement depends on the state of a component at failure; this, in turn, depends on its age. The paper formulates objective functions for the two models and derives recursive equations for their required expected values. It develops a simulation algorithm to calculate these expected values for a complex model. Several examples are used to illustrate the models and the calculations. The data used in the examples are adapted from a real case study of a hospital’s maintenance data for a general infusion pump.