System Reliability Mathmatical Modeling

The reliability mathematical model of a system is the basis of all reliability predictions, optimization, apportionment, and virtually all other system reliability analyses. Because of the importance of the math model, maximum care should be taken in its construction. A system reliability model is defined here as a probability expression which represents the actual system configuration such that when the reliabilities of the system elements are known along with certain other mission parameter values, the expression can be used to calculate the overall system mission reliability. The complexity of the model structure depends upon the complexity of the system it represents and upon the degree of accuracy used in approximating the actual system configuration. The well known series model, wherein the system reliability is given by the product of all the constituent element reliabilities is the simplest type. The accuracy of the series model will generally tend to be very high if the failure of any constituent element will cause the failure of the system of interest. However, more complex model types are required in order to accurately represent a system containing a relatively large number of alternate paths or modes of operation