Structural and Aerodynamic Models in Nonlinear Flight Dynamics of Very Flexible Aircraft

摘要

An evaluation of computational models is carried out for ight dynamics simulations on low-speed aircraft withnvery-flexible high-aspect ratio wings. Structural dynamic models include displacement-based, strain-based, andnintrinsic (first-order) geometrically-nonlinear composite beams, while thin-strip and vortex lattice methods arenconsidered for the unsteady aerodynamics. It is first shown that all different beam finite element models (previouslynderived in the literature fromdifferent assumptions) can be consistently obtained froma single set of equations. Thisnapproach has been used to expand existing strain-based models to include shear effects. Comparisons are made innterms of numerical efficiency and simplicity of integration in flexible aircraft flight dynamics studies. On thenstructural modeling, it was found that intrinsic solutions can be several times faster than conventional ones fornaircraft-type geometries. For the aerodynamic modeling, thin-strip models based on indicial airfoil response arenfound to perform well in situations dominated by small amplitude dynamics around large quasi-static wingndeflections, while large-amplitude wing dynamics require three-dimensional descriptions (e.g. vortex lattice).