Reliability Engineering

17System Reliability Modeling

To design, analyze, and evaluate the reliability and maintainability characteristics of a system, there must be an understanding of the system's relationships to all the subsystems, assemblies, and components. Many times, this can be accomplished through logical and mathematical models of the system that show the functional relationships among all the components, the subsystems, and the overall system. The reliability of the system is a function of the reliabilities of its components and building blocks.

17.1 Reliability Block Diagram

Engineering analysis of the system has to be conducted in order to develop a reliability model. The engineering analysis consists of the following steps:

1. Develop a functional block diagram of the system based on physical principles governing the operations of the system.
2. Develop the logical and topological relationships between functional elements of the system.
3. Determine the extent to which a system can operate in a degraded state, based on performance evaluation studies.
4. Define the spare and repair strategies (for maintenance systems).

Based on the preceding analysis, a reliability block diagram is developed, which can be used to calculate various measures of reliability and maintainability. The reliability block diagram (RBD) is a pictorial way of showing the success or failure combinations for a system. A system reliability block diagram presents a logical relationship of the system, subsystems, and components. Some ...