TABLE OF CONTENTS Given the failure rate of a component and an operational time interval (mission time), one can calculate the reliability of that component. If the component is repairable and the restore rate is estimated, the steady state availability of the component can be calculated. If the failure rates, proof test interval, proof test coverage, and component lifetime are known, one can calculate the average probability of failure.
But the problem is usually much more complicated. Real problems involve systems of many components. Many of these systems have "redundancy" designed into the system in order to maintain successful system operation even when a component fails. How does one calculate reliability or availability of these complex systems?
Several different modeling techniques have been developed. In this chapter block diagrams (also called network modeling), fault trees, and Markov models are presented in a simple introductory way. More advanced and realistic modeling techniques are covered in later chapters.
A systematic approach to model building should be used regardless of the modeling technique (Ref. [1], Chapter 13, page 307). The following steps should be included in one form or another.
Define "what is the intended function?" One must effectively define what components are included in the model. This is normally done by defining failure and excluding components not needed to achieve the desired function.
Obtain failure rate and failure mode data for each component in the system and create a checklist of all components with their failure modes.
Understand how the...
