The Use of Decomposition in the Optimal Design of Reliable Systems

The optimal design problem is to minimize the cost of a system of independent components subject to a lower bound constraint on the system reliability, and upper and lower bounds on the component reliabilities. This problem can be extremely difficult to solve for an arbitrary system, but for the rather general class of S-P systems, the optimal design problem can often be solved via a decomposition of the system structure. From this decomposition there arises a sequence of parallel and series optimal design subproblems that are parametric in the lower bound on the subsystem reliability. Given appropriate assumptions about the input data, these parallel and series subproblems can be easily solved. However, since the parametric solution of one subproblem is typically used as part of the data for a higher-level subproblem, the behavior of these parametric solutions must be investigated. We give conditions that ensure that the overall optimal design problem can be solved.