Optimization of System Reliability via Redundancy and/or Design Considerations

The two traditional methods used in improving the reliability of a multi-stage system are examined. The first method is the creation of redundancy in system components, whereas the second method consists of overdesigning the system components. An Integrated Reliability Optimization Model that includes both of these two methods for improving the reliability of a system is presented. It is shown that under certain assumptions the integrated model reduces to a Redundancy Optimization Model and under certain other assumptions reduces to a Design Optimization Model. Several methods that have been previously suggested for obtaining solutions to the Integrated Optimization Model are reviewed and a generalized solution procedure for such a model is presented. This solution procedure involves the successive solution of two subproblems a number of times. The first subproblem is a design optimization problem that is solved by the Davidon-Fletcher-Powell optimization algorithm. The second subproblem is a reliability redundancy optimization problem that is solved with the heuristic approach of Aggarwal, et al.