Computer aided reliability prediction
This thesis describes a project, sponsored by the Admiralty Surface Weapons Establishment (A.S.W.E), whose objective is to investigate the use of Computer-Aided Design (C.A.D) methods in reliability engineering and, in particular, in reliability prediction. The project evolved as a result of continuous interaction with users whose requirements and comments have assisted in the definition of the project specification which in turn, implied the method of computation (Monte Carlo analysis) and the form of the implementation (a modularly structured program). The project produced a CAD method which aimed to provide: i) a means of predicting the reliability of complex hetero-geneous systems and an aid to estimate their spares requirements in an efficient way. ii) software which is easily extendable, modifiable and, while oriented towards the ICL 1900 range of computers, optimally portable. iii) a mode of documentation which permits the use of the program by reliability engineers who have no previous computing experience. In order to fulfil these requirements it was necessary to incorporate a number of novel features which includes: i) the use of hierarchical structures as a means of modelling the reliability of large and complex systems. ii) the introduction of a modelling device in the form of a controlled switch which allows the modelling of a wide range of dependent failure and repair mechanisms. iii) the transformation of any type of failure and repair distribution into a uniform data structure which permits the easy and efficient handling of any type of distribution function. iv) the use of modular programming and program documentation as a means of providing the necessary efficiency, flexibility and user- accessability. This thesis includes the description of the CAD method and illustrates it by means of a number of examples. Further, it discusses some of the problems of using this method to predict the reliability of mechanical engineering systems. The use of the program by A.S.W.E. contractors and Polytechnic students is described by reference to diverse design examples. Further areas of research and development in relation to the project are given. To assist the reader who may not be equally familiar with the standard terminologies of reliability engineering, statistics and computing used in this thesis, a set of selected definitions is included in one of the appendices.