book is special as not many books on Repairable System Reliability are available in the literature on reliability engineering. All the three authors of this book come from the reputed academic institutes of technology in India, but have also have had rich experience of working on field projects of practical importance. Incidentally, the two of the authors, namely, Rajiv Nandan Rai and Sanjay Kumar Chaturvedi are the postgraduate and doctorate, respectively, of the first Centre of Reliability Engineering established in India by the series Editor in 1983 at the Indian institute of Technology, at Kharagpur. Rajiv Nandan Rai has also served with the Indian Air Force and has had about 20 years of industrial experience in military aviation, which is reflected in the treatment of the subject.
Actually, the research in repairable systems reliability is limited and very few textbooks are available on the subject. The available textbooks generally provide coverage of non-homogeneous Poisson process (NHPP) where the repair effectiveness index (REI) is considered one. Few more textbooks provide treatment of non-parametric reliability analysis of repairable systems. However, this book aims to provide a comprehensive framework for the analysis of repairable systems considering both the non-parametric and parametric estimation of the failure data. The book also provides discussion of generalized renewal process (GRP) based arithmetic reduction of age (ARA) models along with its applications to repairable systems data from aviation industry.
Repair actions in military aviation may not fall under ‘as good as new (AGAN)’ and ‘as bad as old (ABAO)’ assumptions which often find limited uses in practical applications. But actual situation could lie somewhere between the two. A repairable system may end up in one of the five likely states subsequent to a repair: (i) as good as new, (ii) as bad as old, (iii) better than old but worse than new, (iv) better than new, and lastly, (v) worse than old. Existing probabilistic models used in repairable system analysis, such as the perfect renewal process (PRP) and the non-homogeneous Poisson process (NHPP), account for the first two states. In the concept of imperfect repair, the repair actions are unable to bring the system to as good as new state, but can transit to a stage that is somewhere between new and that of one preceding to a failure. Because of the requirement to have more precise analyses and predictions, the GRP can be of great interest to reduce the modelling ambiguity resulting from the above repair assumptions. The authors have discussed to a great extent various possibilities under repair-ability environment and applied them to physical systems. The book also summarizes the models and approaches available in the literature on the analysis of repairable system reliability.
It is expected the book will be very useful to all those who are designing or maintaining repairable systems.
Krishna B. Misra Series Editor
Preface
Conventionally, a repair action usually is assumed to renew a system to its “as good as new” condition. This assumption is very unrealistic for probabilistic modeling and leads to major distortions in statistical analysis. Most of the reliability literature is directed toward non-repairable systems, that is, systems that fail are discarded. This book is mainly dedicated toward providing coverage to the reliability modeling and analysis of repairable systems that are repaired and not replaced when they fail.
During his journey in the military organization, the first author realized that most of the industries desire to equip its scientists, engineers, and managers with the knowledge of reliability concepts and applications but have not been able to succeed completely. Repairable systems reliability analysis is an area where the research work is quite limited and very few text books are available. The available text books are also limited in providing a coverage only up to the concepts of non-homogeneous Poisson process (NHPP) where the repair effectiveness index (REI) is considered one. Few more textbooks provide knowledge only on non-parametric reliability analysis on repairable systems.
This book provides a comprehensive framework for the modeling and analysis of repairable systems considering both the non-parametric and parametric estimation of the failure data. The book provides due exposure to the generalized renewal process (GRP)–based arithmetic reduction of age (ARA) models along with its applications to repairable systems data from aviation industry. The book also covers various multi-criteria decision making (MCDM) techniques, integrated with repairable systems reliability analysis models to provide a much better insight into imperfect repair and maintenance data analysis. A complete chapter on an integrated framework for procurement process is added which will of a great assistance to the readers in enhancing the potential of their respective organization. It is intended to be useful for senior undergraduate, graduate, and post-graduate students in engineering schools as also for professional engineers, reliability administrators, and managers.
This book has primarily emerged from the industrial experience and research work of the authors. A number of illustrations have been included to make the subject pellucid and vivid even to the readers who are new to this area. Besides, various examples have been provided to showcase the applicability of presented models and methodologies, besides, to assist the readers in applying the concepts presented in the book.
The concepts of random variable and commonly used discrete and continuous probability distributions can readily be seen in various available texts that deal with reliability analysis of non-reparable systems. The reliability literature is in plenty to cover such aspects in reliability data analysis where the failure times are modeled by appropriate life distributions. Hence, the readers are advised to refer to any such text book on non-repairable systems reliability analysis for a better comprehension of this book.
Chapter 1 presents various terminologies pertaining to repairable systems followed by the description of repair concepts and repair categories.
The mean cumulative function (MCF)–based graphical and non-parametric methods for reparable systems are simple yet powerful option available to analyze the fleet/system events recurrence behavior and their recurrence rate. Chapter 2 is dedicated to MCF-based non-parametric analysis through examples with a case study of remotely operated vehicle (ROV).
The renewal and homogeneous Poisson processes (HPPs) followed by an exhaustive description of NHPP are covered in Chapter 3 along with solved examples. Thereafter, the chapter brings out a detailed description of ARA and ARI models along with their applicability in maintenance. The chapter also derives the maximum likelihood estimators (MLEs) for Kijima virtual age models with the help of GRP. The models are demonstrated with the help of suitable examples.
Chapter 4 provides various goodness-of-fit (GOF) tests for repairable systems and their applications with examples.
Chapter 5 presents various reliability and availability-based maintenance models for repairable systems. This chapter introduces the concept of high failure rate component (HFRC)–based thresholds and provides maintenance models by considering the “Black Box” (BB) approach followed by the failure mode (FM) approach. All the models are well-supported with examples.
This book presents modified failure modes and analysis (FMEA) model in Chapter 6. This model is based on the concept of REI propounded by Kijima and is best applicable to the repairable systems reliability analysis.
Chapter 7 provides an integrated approach for weapon procurement systems for military aviation. The combined applications of MCDM tools like AHP, ANP, and optimization techniques can be seen in this chapter. This model can be used for other industries procurement policy as well.
Chapter 8 is aimed at reducing the overhaul time of a repairable equipment