Optimal redundancy allocation for systems considering common-cause failures

The redundancy allocation problem is formulated with the objective of maximizing system reliability in the presence of common cause failures. These types of failures can be described as events that cause simultaneous failure of multiple components due to a common cause. The redundancy allocation problem involves the optimal selection of redundancy levels and combination of components to maximize reliability given cost and weight constraints. This new problem formulation offers several distinct benefits compared to traditional problem formulations. For some systems, recognition of common cause failure events is necessary so that the overall system reliability estimation, and the associated design, correspond to the true system reliability behavior in a more realistic way. This research study represents one of the first efforts to analyze the mixing of components, together with the inclusion of common cause failure events, to develop optimal solutions to the redundancy allocation problem. A non-linear optimization model is presented. Solutions to an illustrative problem are obtained to demonstrate consideration of common cause failures will lead to different and preferred "optimal" design strategies.