Multi-disciplinary optimization (MDO) methods have become mature as software applications have been developed and distributed in Nordic countries and elsewhere. Typically, engineers formulate concept design problems using multiple system-level responses to allow simultaneous optimization along a Pareto trade-off frontier. These tools make use of trade-off graphs depicting each design concept as a point in a scatter plot, to observe the frontier versus dominated solutions. Often lost is the practical design engineering considerations of the equipment components that compose the system. In particular, there are operational performance limits of the equipment components, usually expressed as safety margins. In an MDO formulation, these margins are often modelled with fixed constraint limits. With optimization, the MDO search can then often drive these constraints active in the considered Pareto optimal solutions. That is, MDO methods can potentially drive a designer toward aggressive risky concepts on equipment margins. Hence, our research questions may be formulated as follows: May margin constraints be mapped or converted to system level objective functions and effectively traded-off against system level requirements? If so, would this approach enable more robust design concepts? In this work, we formulate a MDO problem allowing design performance requirements to be traded off against component performance limits. This will facilitate feasible design configurations that are not only high performing at a systems level, but are also more robust to design margin considerations. We have shown that overall improved designs can be generated when trading off performance limits slightly but greatly increasing the constraint margin safety margins. We do this by considering a family of Pareto frontiers at several levels of constraint margin limits. This highlights the relative sensitivity of component limits with performance levels, by adjusting either the performance requirements or engineering margins.
