Collaborative optimization of systems involving discrete design at the discipline level

The multidisciplinary design optimization technique known as collaborative optimization is applied to two example problems to illustrate the flexibility that the technique extends to disciplinary design teams. In the first problem, disciplinary design variables are discrete-valued representing the cross-sectional dimensions of standardized shapes for structural members in a frame. In the second problem, discrete disciplinary design variables are used to represent the choice between different structural configurations of a truss tower. In both problems, disciplinary design was performed by the non-gradient-based strategy, exhaustive search. Nevertheless, system-level optimization was performed by a gradient-based strategy using simple formulas for the necessary gradients.