Fuzzy fault tree analysis of the marine diesel engine Jacket water cooling system

Abstract

This article presents a case study of fuzzy Fault Tree Analysis (FTA) method application to study of the reliability of Jacket cooling water system of a marine diesel engine. Due to the uncontrollable working conditions such as ship mobility, states of loading and weather conditions, it is difficult to get the exact value of failure probability of the basic components including in the system. To overcome the over and under estimation of the failure probability of basic events as well as the probability of the undesired event of FTA, fuzzy set theory is applied in FTA. Fuzzy failure rate of the system is calculated by fuzzy numbers and fuzzy operators. The result of the FTA is given by fuzzy probability which can compensate the vagueness or uncertainty of probability of basic events and engineering errors. Not only the reliability of the jacket water cooling system but also the importance measure of the basic events of cooling system are analyzed by fuzzy FTA method. Fuzzy probability ranking method and Graded Mean Integration Representation (GMIR) distance method are proposed to use in calculation of the fuzzy importance measures of the components of the system. From this study, it can be concluded that the jacket water cooling system analyzed is highly reliable and the basic event of the failure of the supply air is the most critically important component in the major of events in the system.