Comparison of multidisciplinary design optimization codes for conceptual and preliminary wing design

The results produced by t two multidisciplinary design optimization program s for the analysis and optimum design of a benchmark regional aircraft wing are compared. One of the programs uses a simple beam model and is suitable for conceptual design whereas the other uses a three-dimensional finite el ement model and is suitable fur preliminary design. Results for stress, dis placement, vibration and Butter analyses of the initial design configuratio n show good agreement, as do those far optimization with stress and flutter constraints. However optimization fur a set of limiting wing twist displac ements caused by aileron loading shows a 20% difference in design variable mass between the two models, with the preliminary design model producing th e lower mass design. This can be explained by the ability of the detailed f inite element model to allow for chordwise variation in skin thickness and chordwise bending effects. Furthermore, the deflection constraints used are obtained from a similar finite element model that has been optimized for a ileron efficiency and therefore present particular problems when using the beam model, which does not allow far such chordwise variation.