Antonio B. Guimaraes Neto

DOI Number: N/A

Conference number: IFASD-2019-043

An analysis of the flight dynamics of flexible aircraft having high-aspect-ratio wings shows that, even if the elastic deformations are not large enough to incur structural-dynamic geometrical nonlinearities, important aerodynamic effects can arise that are geometrically nonlinear in essence. For instance, the dihedral effect of the deformed wing is usually significantly different from that of the undeformed one, leading to unacceptable inaccuracies when analyzing the aircraft response to side gusts. Classical approaches to the aeroelastic modeling of flexible aircraft, using geometrically-linear finite elements, the vortexor doublet-lattice methods, and linear or surface spline interpolation techniques, are unable to represent aerodynamic geometrical nonlinearities, because all the aeroelastic model matrices are calculated a priori for the undeformed aircraft and remain unchanged in the analysis. However, numerical experimentation indicates that, if small deformations occur, then the aerodynamic geometrical nonlinearities can be approximately modeled with an on-line update of the spline matrices to take into account the instantaneous deformed normal directions, without the need to perform the much costlier aerodynamic mesh deformation. This paper aims at the derivation of the equations for the modified generalized aerodynamic forces and at the validation of the proposed method in both static and dynamic conditions.

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In Categories: Aeroelastic Design Applications, IFASD 2019
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