A Computational Method for Structurally Nonlinear Joined Wings Based on Modal Derivatives

Past studies showed that the overconstrained nature of Joined Wings and the strong structural geometric nonlinearities make difficult the use of standard packages of aeroelastic solvers (usually modally reduced and frequency domain based) which have been effectively adopted by the industry for decades. We present here a study on the reduction of the computational cost in presence structural nonlinear effects that cannot be neglected in Joined Wings, even at small angles of attack and attached flow. In particular, a reduced order model is achieved with a basis constituted by vibration modes augmented with the corresponding modal derivatives. The results can be considered excellent when compared to the full order reference solution. However, a convergence test showed that the required number of vectors is relatively high and the basis needs to be often updated to achieve the best performance. More investigations will be necessary for an effective use in the industry and complicate dynamic problems involving the unsteadiness of the aerodynamics.