Reliability analysis with suspended items

Bartlett, Harold John Gregory (1998) Reliability analysis with suspended items. PhD thesis, Queensland University of Technology.

Abstract

Reliability analysis has several important engineering applications. Designers and operators of equipment are often interested in the probability of the equipment operating successfully to a given age - this probability is known as the equipment's reliability at that age. Reliability information is also important to those charged with maintaining an item of equipment, as it enables them to model and evaluate alternative maintenance policies for the equipment. In each case, information on failures and survivals of a typical sample of items is used to estimate the required probabilities as a function of the item's age, this process being one of many applications of the statistical techniques known as distribution fitting. In most engineering applications, the estimation procedure must deal with samples containing survivors (suspensions or censorings); this thesis focuses on several graphical estimation methods that are widely used for analysing such samples. Although these methods have been current for many years, they share a common shortcoming: none of them is continuously sensitive to changes in the ages of the suspensions, and we show that the resulting reliability estimates are therefore more pessimistic than necessary. We use a simple example to show that the existing graphical methods take no account of any service recorded by suspensions beyond their respective previous failures, and that this behaviour is inconsistent with one's intuitive expectations. In the course of this thesis, we demonstrate that the existing methods are only justified under restricted conditions. We present several improved methods and demonstrate that each of them overcomes the problem described above, while reducing to one of the existing methods where this is justified. Each of the improved methods thus provides a realistic set of reliability estimates for general (unrestricted) censored samples. Several related variations on these improved methods are also presented and justified. - i

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ID Code: 36043
Item Type: QUT Thesis (PhD)
Supervisor: Pettitt, Anthony N.
Additional Information: Presented to the School of Mechanical and Manufacturing and Medical Engineering, Queensland University of Technology.
Keywords: Reliability (Engineering) Graphic methods, Distribution (Probability theory), System failures (Engineering) Graphic methods, reliability analysis, reliability estimation, probability distribution, distribution fitting, censored samples, multiple censoring, censored item, suspension, suspended item, graphical methods, thesis, doctoral
Institution: Queensland University of Technology
Copyright Owner: Copyright Harold John Gregory Bartlett
Deposited On: 22 Sep 2010 13:04
Last Modified: 08 Dec 2015 23:48

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