Updated Operational Reliability from Degradation Indicators and Adaptive Maintenance Strategy

Abstract

This chapter is dedicated to the reliability and maintenance of assets that are characterized by a degradation process. The item state is related to a degradation mechanism that represents the unit-to-unit variability and time-varying dynamics of systems. The maintenance scheduling has to be updated considering the degradation history of each item. The research method relies on the updating process of the reliability of a specific asset. Given a degradation process and costs for preventive/corrective maintenance actions, an optimal inspection time is obtained. At this time, the degradation level is measured and a prediction of the degradation is conducted to obtain the next inspection time. A decision criterion is established to decide whether the maintenance action should take place at the current time or postpone. Consequently, there is an optimal number of inspections that allows to extend the useful life of an asset before performing the preventive maintenance action. A numerical case study involving a non-stationary Wiener-based degradation process is proposed as an illustration of the methodology. The results showed that the expected cost per unit of time considering the adaptive maintenance strategy is lower than the expected cost per unit of time obtained for other maintenance policies.

Operational Reliability Metric to Characterize Radar Detection Performability

“…In some cases, the item state may be influenced by other factors such as variable mechanical stresses and variable energy consumption, in addition to a change in the operating conditions and the effect of the environment. Clearly, the reliability and RUL of such equipment will change accordingly [9].…”

A Survey of Predictive Maintenance: Systems, Purposes and Approaches

“…The term "reliability" indicates the probability of a system or a piece of equipment to be in a functional state throughout a specified time interval [79]. Let a random variable T f represent the lifetime of the equipment, the reliability R(t) is given by the following equation:…”

Optimized Maintenance Decision-Making – A Simulation-supported Prescriptive Analytics Approach based on Probabilistic Cost-Benefit Analysis

“…Computational methods involving Monte Carlo tools and additional concepts have been developed to incorporate accordingly described imprecise parameters e.g. into Markov or semi-Markov multi-state (Hubbard, 2014) or continuous degradation models like the Wiener degradation process (Gorjian et al, 2010;Letot et al, 2017;Pei et al, 2018). The latter has attracted increasing attention in recent years due to its significance in Predictive Maintenance, e.g.…”

“…The latter has attracted increasing attention in recent years due to its significance in Predictive Maintenance, e.g. for accurate Remaining Useful Life (RUL) prediction and the capability to consider both time-varying dynamics and unit-to-unit variability, the latter stemming from variations in operational conditions and initial degradation levels (Zhu, Zuo & Cai, 2013;Letot et al, 2017;Pei et al, 2018). For instance, RUL estimation of an aircraft engine has been performed based on lifecycle and performance-deteriorated parameter data without failures (Zhu et al, 2013).…”

“…Zhang et al, 2018). Letot et al (2017) have related the Wiener degradation process to operational reliability and derived strategies for cost-optimized maintenance planning.…”