Optimal Two Dimensional Preventive Maintenance Policy Based on Asymmetric Copula Function

For some kinds of products, the consumers have strict requirements to the reliability of these products in the based warranty period. Then the manufacturer is inclined to provide the two-dimensional preventive maintenance policy to take the usage degree of the product into account. As a result, two-dimensional preventive maintenance policy in the warranty period has recently obtained increasing attention from manufacturers and consumers. In this paper, we focused on the optimization of based warranty cost and proposed a new expected based warranty cost model considering the two-dimensional imperfect preventive maintenance policy from the perspective of the manufacture. Asymmetric copula function was applied to modeling the failure function of the product. And the optimal two-dimensional preventive maintenance period was obtained by minimizing based warranty cost. At last, numerical examples are given to illustrate the proposed models, of which the results prove the model effective and validate

Modeling Spare Parts Demands Forecast under Two-Dimensional Preventive Maintenance Policy

In maintenance practice, there is such a situation where the spare parts replacement should be carried out at the scheduling time of calendar or usage for whichever comes first. The issue of two-dimensional preventive maintenance usually was not addressed by traditional methods, and at present, few studies were focused on this very topic. Based on these considerations, this paper presented the two-dimensional preventive policy where replacements of spare parts are based on both calendar time and usage time. A novel model was developed to forecast spare parts demands under two-dimensional preventive maintenance policy, and a discrete algorithm was presented for solving the mathematical model. A case study was given to demonstrate its applicability and validity, and it was showed that the presented model can be used to forecast spare parts demands as well as to optimize spare parts and preventive maintenance jointly

A Review of Optimization Models and Techniques for Maintenance Decision Support Systems in Small and Medium Industries

The research is based on the fact that decision support systems (DSSs) is needed for maintenance process in commonly industries. Many maintenance functions with varieties optimization models and techniques have been proposed for solving the problems. The aim of this research was to identify those optimization models and techniques to conduct maintenance decision support system in small and medium industries (SMIs). A systematic literature review was performed to gather relevant information. The results shown several trends related in the fields area. Next, the research direction has been suggested to develop the systems

Warranty menu design for a two-dimensional warranty

Fierce competitions in the commercial product market have forced manufacturers to provide customer-friendly warranties with a view to achieving higher customer satisfaction and increasing the market share. This study proposes a strategy that offers customers a two-dimensional warranty menu with a number of warranty choices, called a flexible warranty policy. We investigate the design of a flexible two-dimensional warranty policy that contains a number of rectangular regions. This warranty policy is obtained by dividing customers into several groups according to their use rates and providing each group a germane warranty region. Consumers choose a favorable one from the menu according to their usage behaviors. Evidently, this flexible warranty policy is attractive to users of different usage behaviors, and thus, it gives the manufacturer a good position in advertising the product. When consumers are unaware about their use rates upon purchase, we consider a fixed two-dimensional warranty policy with a stair-case warranty region and show that it is equivalent to the flexible policy. Such an equivalence reveals the inherent relationship between the rectangular warranty policy, the L-shape warranty policy, the step-stair warranty policy and the iso-probability of failure warranty policy that were extensively discussed in the literature

A unified methodology of maintenance management for repairable systems based on optimal stopping theory

This dissertation focuses on the study of maintenance management for repairable systems based on optimal stopping theory. From reliability engineering’s point of view, all systems are subject to deterioration with age and usage. System deterioration can take various forms, including wear, fatigue, fracture, cracking, breaking, corrosion, erosion and instability, any of which may ultimately cause the system to fail to perform its required function. Consequently, controlling system deterioration through maintenance and thus controlling the risk of system failure becomes beneficial or even necessary. Decision makers constantly face two fundamental problems with respect to system maintenance. One is whether or when preventive maintenance should be performed in order to avoid costly failures. The other problem is how to make the choice among different maintenance actions in response to a system failure. The whole purpose of maintenance management is to keep the system in good working condition at a reasonably low cost, thus the tradeoff between cost and condition plays a central role in the study of maintenance management, which demands rigorous optimization. The agenda of this research is to develop a unified methodology for modeling and optimization of maintenance systems. A general modeling framework with six classifying criteria is to be developed to formulate and analyze a wide range of maintenance systems which include many existing models in the literature. A unified optimization procedure is developed based on optimal stopping, semi-martingale, and lambda-maximization techniques to solve these models contained in the framework. A comprehensive model is proposed and solved in this general framework using the developed procedure which incorporates many other models as special cases. Policy comparison and policy optimality are studied to offer further insights. Along the theoretical development, numerical examples are provided to illustrate the applicability of the methodology. The main contribution of this research is that the unified modeling framework and systematic optimization procedure structurize the pool of models and policies, weed out non-optimal policies, and establish a theoretical foundation for further development

Prediction of Warranty Costs

Disertační práce se zabývá problematikou záručních nákladů a jejich predikce při poskytování jednorozměrných a zejména dvourozměrných záruk za jakost. Práce je zaměřena na návrh prakticky použitelných metod a postupů, které umožní dodavatelům a výrobcům získat informace nezbytné pro racionální rozhodování při poskytování záruk za jakost u složitých produktů již v počátečních etapách jejich životního cyklu. V úvodu práce je přehledně shrnut a zhodnocen současný stav řešené problematiky. V první stěžejní části práce jsou analyzovány možnosti predikce záručních nákladů u složitých produktů při použití jednorozměrných a zejména dvourozměrných záruk za jakost. Tato část práce obsahuje podrobný rozbor možností predikce bezporuchovosti systémů a prvků. V návaznosti je navržen způsob začlenění predikce záručních nákladů do metody FMEA/FMECA. V druhé stěžejní části práce je navržen postup, který umožňuje stanovit okamžik ukončení záruční doby při použití dvourozměrné záruky, když nejsou k dispozici dostatečné informace z reklamačních řízení. Tato část práce je doplněna praktickou aplikací navrženého postupu. Ve třetí stěžejní části je charakterizován časový vývoj záručních nákladů a souvisejících ukazatelů a navržen způsob predikce jejich časového vývoje. V této části práce je také navržen způsob průběžného sledování a vyhodnocování záručních nákladů a souvisejících ukazatelů.The thesis deals with warranty costs and their prediction when providing one-dimensional and two-dimensional warranties. This thesis focuses on the presentation of practically applied methods and procedures which enable suppliers and manufacturers to get the information necessary for rational decision making while providing warranties for complex products as early as in the initial stages of their life cycle. The thesis starts with a concise summary and evaluation of a present state of the issue. In the first part of the thesis the possibilities of warranty costs prediction for complex products are analyzed when using one-dimensional and namely two-dimensional quality warranties. In this part there is a detailed analysis of different possibilities when predicting systems and items reliability. Next, there is introduced the way of integrating warranty costs prediction into the FMEA/FMECA method. In the second part of the thesis there is specified the procedure for determining the moment of warranty period termination using two-dimensional warranty in case sufficient data from complaint procedure is not available. In the third part the time development of warranty costs and related measures are determined, and the way of prediction of their time development is suggested. The way of continuous monitoring, and evaluating warranty costs and related measures are also introduced in this part of the thesis.

Planejamento operacional de cadeias de suprimento de peças de reposição integrado com sistemas inteligentes de manutenção

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Produção, Florianópolis, 2014A falta de peças de reposição e a consequente ineficiência da manutenção acarretam baixa disponibilidade de equipamentos, prejudicando o nível de serviços e aumentando os custos de produção no setor industrial. A demanda de peças de reposição é esporádica e errática, o que dificulta sua previsão com métodos e ferramentas estatísticas disponíveis. Nesse sentido, o uso de Sistemas Inteligentes de Manutenção (IMS) tem sido estudado para apoiar o processo de previsão de falhas em equipamentos e, dessa forma, contribuir para a disponibilidade e competitividade de sistemas produtivos. Nesse contexto, o presente trabalho propõe um método, o qual tem por objetivo integrar informações providas por Sistemas Inteligentes de Manutenção ao planejamento operacional da cadeia de suprimentos de peças de reposição. Os resultados obtidos indicam que o método desenvolvido é capaz de gerar redução dos custos e assegurar níveis de serviços pré-determinados.Abstract: The lack of spare parts and inefficient maintenance lead to low availability of equipment, damaging the service level and increasing costs of production in the industrial sector. Spare parts demand is sporadic and erratic, impairing its prediction with available statistical tools. The use of Intelligent Maintenance Systems (IMS) has been studied to support the process of predicting equipment failures and thus contributing to more competitive productive systems. In this context, this study proposes a method, which aims to integrate information provided by Intelligent Maintenance Systems into the operational planning of spare parts supply chain. Obtained results indicate that the developed method is able to generate spare parts supply chain's cost reduction, while ensuring pre-determined service levels

Architecting Fail-Safe Supply Chains / Networks

Disruptions are large-scale stochastic events that rarely happen but have a major effect on supply networks’ topology. Some examples include: air traffic being suspended due to weather or terrorism, labor unions strike, sanctions imposed or lifted, company mergers, etc. Variations are small-scale stochastic events that frequently happen but only have a trivial effect on the efficiency of flow planning in supply networks. Some examples include: fluctuations in market demands (e.g. demand is always stochastic in competitive markets) and performance of production facilities (e.g. there is not any perfect production system in reality). A fail-safe supply network is one that mitigates the impact of variations and disruptions and provides an acceptable level of service. This is achieved by keeping connectivity in its topology against disruptions (structurally fail-safe) and coordinating the flow through the facilities against variations (operationally fail-safe). In this talk, I will show that to have a structurally fail-safe supply network, its topology should be robust against disruptions by positioning mitigation strategies and be resilient in executing these strategies. Considering “Flexibility” as a risk mitigation strategy, I answer the question “What are the best flexibility levels and flexibility speeds for facilities in structurally fail-safe supply networks?” Also, I will show that to have an operationally fail-safe supply network, its flow dynamics should be reliable against demand- and supply-side variations. In the presence of these variations, I answer the question “What is the most profitable flow dynamics throughout a supply network that is reliable against variations?” The method is verified using data from an engine maker. Findings include: i) there is a tradeoff between robustness and resilience in profit-based supply networks; ii) this tradeoff is more stable in larger supply networks with higher product supply quantities; and iii) supply networks with higher reliability in their flow planning require more flexibilities to be robust. Finally, I will touch upon possible extensions of the work into non-profit relief networks for disaster management