Jointly optimizing lot sizing and maintenance policy for a production system with two failure modes

This paper develops a cost rate function (CRF) to identify the optimum interval and frequency of inspection and restoration of aircraft's repairable components which are undergoing aging, and whose failures are hidden, i.e. are detectable by inspection or upon demand. The paper considers two prevalent strategies, namely Failure Finding Inspection (FFI), and a combination of FFI with restoration actions (FFI+Res), for both the “non-safety effect,” and the “safety effect” categories of hidden failures. As-bad-as-old (ABAO) inspection effectiveness, and as-good-as-new (AGAN) restoration effectiveness are considered. In case of repair due to findings by inspection, as-bad-as-old repair effectiveness is considered. The proposed method considers inspection and repair times, and takes into account the costs associated with inspection, repair, and restoration; and the potential losses due to the inability to use the aircraft (maintenance downtime). It also considers the cost associated with accidents caused by the occurrence of multiple failure. The approach used in this study for risk constraint optimization is based on the mean fraction of time during which the unit is not functioning within inspection intervals (MFDT), and the average interval unavailability behavior within the restoration period. In the case of an operational limit, when it is not possible to remove the unit for restoration, or one needs to use the unit longer than the expected operating time, the paper introduces an approach to analyzing the possibility of and conditions for providing an extension to the restoration interval that satisfies the risk constraints and the business requirements at the same time.

/pdf/cost-based-risk-analysis-to-identify-inspection-and-s6svpqay37.pdf

Cost Based Risk Analysis to Identify Inspection and Restoration Intervals of Hidden Failures Subject to Aging

Reliability analysis of k-out-of-n: F balanced systems with multiple functional sectors

The industry has entered on the Fourth Industrial Revolution, the so-called Industry 4.0, with global markets and strong competition, some traditional manufacturing firms are implementing new maintenance innovations and policies, based on digitalisation and data driven approach, but also based on servitisation. The implementation of these new equipment maintenance business models, could require new organisational approach at different levels. Different sorts of integration are arranged, in vertical with a flat structure of intelligent, flexible and autonomous units working integrated, in horizontal with a strong external and internal supply chain integration, and in transverse, with an integrated approach that link internal and external stakeholders. A new prescriptive maintenance business model for equipment exploiting digitalisation opportunities, including stakeholder relationship is proposed. Different perspectives such as organisational, innovation and sustainability have been adopted to discuss the implications of the proposal. The social value potentially gained as well as the alignment with the SDGs are discussed as well.

https://www.mdpi.com/2071-1050/13/1/216/pdf

New Business Models from Prescriptive Maintenance Strategies Aligned with Sustainable Development Goals

In response to the environmental issues triggered by global warming, worldwide companies gradually put the factor of carbon emission into the process of product lifecycle, developing green technology or adopting cleaner production aimed at sustainable development. Lean Six Sigma has advantages of cutting waste and facilitating process improvements as well as system analysis, helping enterprises create the overall business benefits in the value chain. Used in the renewable energy industry, it can promote the triple bottom line (TBL), the performance of sustainable production for corporate profit, social responsibility and environmental responsibility. Therefore, this work took the process performance of the electric scooter water-cooling green motor manufactured in Taiwan with the world’s highest density of scooters as a case study. The developed performance evaluation and improvement model for manufacturing scheduling and process quality achieved the goal of economic benefits of enhancing process ...

/pdf/lean-six-sigma-applied-to-process-performance-and-66py100tlo.pdf

Lean Six Sigma applied to process performance and improvement model for the development of electric scooter water-cooling green motor assembly

This article presents a real successful implementation of lean six sigma methodology to continuously improve the baggage flow in a baggage handling system (BHS), by identifying the causes of mishan...

Improving baggage flow in the baggage handling system at a UAE-based airline using lean Six Sigma tools

This paper develops a dynamic maintenance strategy for a system subject to aging and degradation. The influence of degradation level and aging on system failure rate is modeled in an additive way. Based on the observed degradation level at the inspection, repair or replacement is carried out upon the system. Previous researches assume that repair will always lead to an improvement in the health condition of the system. However, in our study, repair reduces the system age but on the other hand, increases the degradation level. Considering the two-fold influence of maintenance actions, we perform reliability analysis on system reliability as a first step. The evolution of system reliability serves as a foundation for establishing the maintenance model. The optimal maintenance strategy is achieved by minimizing the long-run cost rate in terms of the repair cycle. At each inspection, the parameters of the degradation processes are updated with maximum a posteriori estimation when a new observation arrives. The effectiveness of the proposed model is illustrated through a case study of locomotive wheel-sets. The maintenance model considers the influence of degradation and aging on system failure and dynamically determines the optimal inspection time, which is more flexible than traditional stationary maintenance strategies and can provide better performance in the field.

/pdf/a-dynamic-prescriptive-maintenance-model-considering-system-4x9k2ah416.pdf

A dynamic prescriptive maintenance model considering system aging and degradation

A prospective study of maintenance deviations using HFACS-ME

Software vulnerabilities trend over time has been proposed by various researchers and academicians in recent years. But none of them have considered operational coverage function in vulnerability d ...

https://onlinelibrary.wiley.com/doi/pdf/10.1002/qre.2380

Coverage‐based vulnerability discovery modeling to optimize disclosure time using multiattribute approach

The increasing pace of mechanization and automation of industries has enhanced the business risks associated with nonfunctioning of production units and other engineering systems. In general, such units and engineering systems are expected to function round the clock without failure. However, owing to design deficiencies or the influence of operational stresses, these systems are not always able to meet the users' requirements in terms of system performance. This is often attributed to poorly designed reliability and maintainability characteristics, combined with poor maintenance and product support strategies. If the designed reliability and maintainability characteristics are poor and the maintenance organization is unable to meet the requirements, this may result in a poor availability performance. Even though high reliability is desirable to reduce the costs of maintenance and maintenance preparedness, the benefits of improved maintainability should not be ignored in achieving the required availability performance. Availability is the most commonly used measure of the state of plant and systems all over the world.



In this chapter, a brief discussion on the concepts of availability and maintainability is presented with some examples.


Keywords:

availability performance;
reliability performance;
maintainability performance;
risk;
safety;
maintenance support

Uday Kumar

Papers

Improving baggage flow in the baggage handling system at a UAE-based airline using lean Six Sigma tools

A dynamic prescriptive maintenance model considering system aging and degradation

A prospective study of maintenance deviations using HFACS-ME

Coverage‐based vulnerability discovery modeling to optimize disclosure time using multiattribute approach

Availability and Maintainability