Integrated reliability analysis system (IRAS)

Abstract

This paper will introduce a computer aided reliability analysis system, IRAS, which is a Unix‐based software package. It provides the following features: a model builder, failure mode effect and criticality analysis (FMECA), fault tree synthesis and analysis (FTA) and real time fault location (RTFL). 1. The model builder allows the creation of reliability models for production systems, which are able to reflect the initiation and propagation of serious deviations outside the production and performance tolerances. The modelling procedure allows hierarchical modelling. 2. The failure mode effect and criticality analysis (FMECA) option uses the causal trees and cause‐consequence diagrams that are created automatically from the IRAS model data base. The trees can be analysed by the user and the basic events can be grouped according to their criticality, probability and severity. 3. The fault tree analysis and synthesis (FTA) option enables the graphical analysis of fault trees. The generated tree can be trimmed automatically or by the user. It is also possible to extract the minimal cut‐set from the complete tree. 4. RTFL enables the fast detection of the most probable fault locations in the system, during the continuous measuring of sensors of the production system and comparing the signals with the expected values of the stored operational vector. It alarms the user in case of serious deviations, thus reducing the out of work stage of the system by making quicker and more efficient reaction of the maintenance facility operators. The failure searching time reduction results in lower maintenance cost.