R&M of Systems With Exponential Time Densities

Expressions for availability, restore rate, failure rate, mean time to first failure, and reliability function are developed for some combinations of series and parallel units. The conditions and assumptions which apply to the derivations are given, and reliability parameters are described and their relationships and meanings are discussed. Time dependent availability is discussed to indicate the time required for the system to reach a steady state condition. A detailed discussion is given for the derivation of steady state availability, failure rate, and restore rate for two unlike parallel and two unlike series units, and results are generalized to n units. An example illustrates the derivation of mean time to first failure. Examples are worked to illustrate the method of calculating the reliability parameters for systems of series and parallel units.