Handbook of Reliability, Availability, Maintainability and Safety in Engineering Design - Part 66 studies the combination of various methods of designing for reliability, availability, maintainability and safety, as well as the latest techniques in probability and possibility modelling, mathematical algorithmic modelling, evolutionary algorithmic modelling, symbolic logic modelling, artificial intelligence modelling, and object-oriented computer modelling, in a logically structured approach to determining the integrity of engineering design. . | 634 5 Safety and Risk in Engineering Design .V t C t is obtained by multiplying the of the random variables together EzN t EzC t EzN t C t where N t and C t are independent. Cause-Consequence Analysis for Safety Systems Design Cause-consequence analysis for safety systems design is fundamentally a combinatorial symbolic logic technique utilising the symbolic logic of fault-tree analysis FTA reliability block diagramming RBD and event tree analysis ETA . Each of these techniques has unique advantages and disadvantages. In most complex safety systems designs it is beneficial to construct a model using one technique then transform that model into the domain of another technique to exploit the advantages of both. Fault trees are generated in the failure domain reliability diagrams are generated in the success domain and event trees are generated in both the success and failure domains. Methodology to transform any one of the above models into the other two by translating equivalent logic from the success to failure or failure to success domains is considered later. Probabilities are propagated throughout the logic models to determine the probability that a system will fail . its risk or the probability that a system will operate successfully . its reliability. Probability data may be derived from available empirical data or if quantitative data are not available then subjective probability estimates may be used. Cause-consequence analysis for safety systems design explores the system s responses to an initiating deviation from predetermined norms such as the limits of safe operating parameters and enables evaluation of the probabilities of unfavourable outcomes at each of a number of mutually exclusive loss levels depending upon the extent of deviation from these norms. The deviation beyond a set limit is designated an event. The analysis thenbegins with an initiating event and performs a forward bottom-up analysis using ETA. This technique .
