Fuel burn Minimization Including Dynamic Aeroelastic Constraint for Free-flying Vehicle Under Geometrically Nonlinear Deformations

In recent times aircraft designs are moving towards configurations featuring higher aspect ratios with the objective of improving aerodynamic performances. As a consequence, geometrically nonlinear deformations become increasingly prevalent, posing additional challenges in the evaluation of aeroelastic stability when accounting for a flutter constraint in a design optimization process. To address this we implemented a nonlinear flutter constraint in a multidisciplinary design optimization of aircraft, instead of a linear one that is currently the standard in this kind of study. The framework developed for this work performs gradient-based optimization of fuel burn considering aggregated constraints. In particular, aeroelastic quantities are computed employing a low-order geometrically nonlinear beam model (making stability considerations tractable for an optimization process) for the wing and differentiated via AD in reverse mode. The implementation is demonstrated with a sample optimization problem featuring a BWB aircraft.