On the maintenance concept for a technical system : a framework for design

Abstract

This study aims at setting forth a framework that is intended to be useful in the systematization of the design of the maintenance concept for a technical system in an using organization.The maintenance concept, essentially, is the set of ordered maintenance rules prescribing what maintenance should be carried out when.On the one hand, such a framework permits to fit in already available but fragmentary research results, thus identifying the lacunae in knowledge requiring further research.On the other hand, it can be used as an instrument, in actual design of a maintenance concept for a technical system to be introduced in an organization, or to evaluate existing maintenance concepts.The introductio.n in chapter I shows the relevance of the maintenance concept with respect to maintenance control.Chapter 2 presents a discussion of the aspects of the technical , system and of the using organization that have to be accounted for in a framework for maintenance concept design.In chapter 3, the literature dealing with the question "what maintenance should be carried out when" is reviewed.The contributions are classified into a mathematical approach and an engineering approach.In the mathematical approach, the problem is considerably simplified in order to be able to obtain optimal maintenance policies.In the engineering approach, the real problem is considered, aiming at a satisficing solution.In chapter 4, a framework for the fundamental design process of the maintenance concept is presented.A fundamental approach is concerned with the way in which ideally the maintenance concept should be designed.The approach is decomposed into the following four phases: X -technical system analysis; -elementary maintenance generation; -combinatorial maintenance generatio.n;-maintenance concept determination.Teahniaat system analysis supplies that information about the technical system which is required in the subsequent phases in maintenance concept design.Failure behaviour analysis identifies the process-failure combinations, i.e. the failures of the technical system unambiguously related to their underlying physical processes.Failure consequence analysis concentrates on determining the consequences of the process-failure combinations identified.Hardware structure analysis deals with the replaceability and accessibility of the parts of the technical system.Elementary maintenanae generation aims at relating a set of alternative elementary maintenance rules to each process-failure combination distinguished, on the basis of its behaviour and taking into account its consequences and the constraints imposed by the using organization.An elementary maintenance rule is a directive prescribing a maintenance operation and when it should be carried out.With respect to a process-failure combination, it concentrates on the effectiveness of the categories of maintenance activation distinguished i.e.: failure based maintenance; -use based maintenance; -condition based maintenance.Further, it deals with the effectiveness of maintenance operations.This is considered to be a technical problem outside the scope of this study, as it requires knowledge and understanding of the physical processes underlying failure, of expected technical consequences of failure and of maintenance technology.