Robust Structural Design for Active Aeroelastic Wing with Aerodynamic Uncertainties

A multidisciplinary design study for Active Aeroelastic Wing technology considering the uncertainty in maneuver loads estimated by linear aerodynamic theory is presented. The study makes use of a design of experiments/response surface methodology and modal-based structural optimization to construct deterministic relationships between wing structural weight and control laws design, based on linear aerodynamics. CFD Navier-Stokes analysis is then used to define typical differences between rigid aerodynamic loads as predicted by nonlinear and linear theory. These differences are then used to define aerodynamic uncertainties in a probabilistic manner, which are propagated, through Latin Hypercube Sampling and modal-based static aeroelastic analysis, to a response function that represents the magnitude of structural redesign. Structural designs then are sought that are both low weight and whose performance is relatively invariant in the presence of load uncertainty. The motivation for this study is derived by the frequent inability to accurately represent maneuver loads on an aircraft structure, which often requires redesign (sometimes major) late in the design process as loads predictions become more accurate.