Repairable Systems Reliability Analysis. Rajiv Nandan Rai

Repairable Systems Reliability Analysis

Repairable Systems Reliability Analysis - Rajiv Nandan Rai

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Types of repair Figure 1.2 Various techniques for reliability analysis Figure 2.1 A MCF example Figure 2.2 An improving system Figure 2.3 A stable system Figure 2.4 A deteriorating system Figure 2.5 History and distribution of failures observed at age t Figure 2.6 MCF plot of Example 2.2 Figure 2.7 Graphical plots of Example 2.3 Figure 2.8 MCF with confidence bounds of Example 2.2 data Figure 2.9 MCF plot of Example 2.4 Figure 2.10 A ROV. (Image taken from: https://www.pinterest.com/pin/552676185495210644/?nic=1) Figure 2.11 MCF by combining all failure modes Figure 2.12 Event plot for each system Figure 2.13 MCF plot of each system Figure 2.14 Grouping of systems based on performance behavior Figure 2.15 Event plot of all three groups Figure 2.16 MCF plot of all three groups Figure 3.1 Bathtub-shaped intensity function Figure 3.2 Conditional probability of occurrence of failures Figure 3.3 Photograph of an aero engine Figure 3.4 Intensity function plot for Example 3.1 Figure 3.5 Intensity function plot for Example 3.2 Figure 3.6 Intensity function plot for Example 3.3 Figure 3.7 Availability plot for Example 3.3 Figure 5.1 Reliability-based HFRC threshold Figure 5.2 Availability-based threshold for HFRC Figure 5.3 Flying task vs. availability Figure 6.1 q vs. F(vi | vi–1) for FM1 Figure 6.2 q vs. F(vi | vi–1) for FM2 Figure 6.3 q vs. F(vi | vi–1) for FM3 Figure 7.1 Overview of the approach Figure 7.2 Evaluation of alternatives through ANP Figure 7.3 Evaluation of APE through AHP Figure 8.1 Overview of Chapter 8 Figure 8.2 Propagation of variability between workstations in series Figure 8.3 Work flow/work stations for engine overhaul line Figure 8.4 Work flow/work stations for LPCR blades Figure 8.5 Work flow/work stations for CCOC Figure 8.6 Work flow/work stations for LPTR blades repair

      1.1 Introduction

      A system is a collection of mutually related items, assembled to perform one or more intended functions. Any system majorly consists of (i) items as the operating parts, (ii) attributes as the properties of items, and (iii) the link between items and attributes as interrelationships. A system is not only expected to perform its specified function(s) under its operating conditions and constraints but also expected to meet specified requirements, referred as performance and attributes. The system exhibits certain behavioural pattern that can never ever be exhibited by any of its constituent items or their subsets. The items of a system may themselves be systems, and every system may be part of a larger system in a hierarchy. Each system has a purpose for which items, attributes, and relationships have been organized. Everything else that remains outside the boundaries of system is considered as environment from where a system receives input (in the form of material, energy, and/or information) and makes output to the environment which might be in different form as that of the input it had received. Internally, the items communicate through input and output wherein output(s) of one items(s) becomes the input(s) to others. The inherent ability of an item/system to perform required function(s) with specified performance and attributes when it is utilized as specified is known as functionability [1]. This definition differentiates between the terms functionality and functionability where former is purely related to the function performed whereas latter also takes into considerations the level of performance achieved.

      Despite the system is functionable at the beginning of its operational life, we are fully aware that even after using the perfect design, best technology available for its production or the materials from which it is made, certain irreversible changes are bound to occur due to the actions of various interacting and superimposing processes, such as corrosion, deformations, distortions, overheating, fatigue, or similar. These interacting processes are the main reason behind the change in the output characteristics of the system. The deviation of these characteristics from the specifications constitutes a failure. The failure of a system, therefore, can be defined as an event whose occurrence results in either loss of ability to perform required function(s) or loss of ability to satisfy the specified requirements (i.e., performance and/or attributes). Regardless of the reason of occurrence of this change, a failure causes system to transit from a state of functioning to a state of failure or state of unacceptable performance. For many systems, a transition to the unsatisfactory or failure state means retirement. Engineering systems of this type are known as non-maintained or non-reparable system because it is impossible to restore their functionability within reasonable time, means, and resources. For example, a missile is a non-repairable system once launched. Other examples of non-repairable systems include

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