FUZZY LOGIC APPLICATIONS IN RELIABILITY ENGINEERING

Abstract

It is well known that conventional reliability analysis using probabilities has been found to be inadequate to handle uncertainity of failure data and modelling. To overcome this problem the concept of fuzzy probability has been used in the evaluation of reliability of systems. It has been amply demonstrated that the fuzzy set theory can be conveniently used for system reliability evaluation, particularly when there exists uncertainity in the failure data. In reality, even though one may use the best data collection procedures, failure data uncertainity always exists. In the presented work a concept of possibility of failure i.e. fuzzy set defined on probability of failure i.e. fuzzy set defined on probability space is used to evaluate system reliability. The notion of the possibility of failure is more predictive than that of the probability of failure, the latter is a limiting case of the former. In the presented approach a fuzzy-set analysis is made for various system structures viz. fault tree, event trees etc. Such analysis can not be made by hand calculations due to complexity of trees. Hence a computer algorithm is developed for each case