Development of multiple cycle coupling suspension in the optimization of complex systems

The design of complex engineering systems requires an initial decomposition of the system into sub-systems. These systems are linked together by couplings, which represent output data transference from one sub-system to another. Because complex engineering systems can have hundreds or thousands of such couplings, the optimization of these systems is often quite difficult, if not impossible. To reduce the optimization time, it becomes important that a system designer have the ability to select couplings that have little effect on the solution accuracy, and temporarily remove them. Previous coupling strength analysis methods have not related the effect of a coupling's removal for multiple cycles to solution accuracy. The method presented here identifies weak couplings based on their relationship to the objective function and constraints in the overall system optimization problem. The couplings are then suspended for multiple cycles of the multidisciplinary design optimization process. Discussion of the application of this new method follows, as well as implementation on a decomposed analytical problem. The method significantly reduces the number of subsystem analyses required to optimize the decomposed problem by suspending couplings for multiple design cycles. As a result of the system reduction, considerable computational saving are made without introducing significant error into the results of the optimization. The trade-offs between computational savings and solution accuracy are also shown and discussed.