The recently developed Parametric Flutter Margin method is expanded to perform efficient sensitivity studies where linear and nonlinear flutter characteristics are calculated for changes in selected parameters. Two approaches are suggested: one for structural, aerodynamic or control parameters that can be formulated as single-input-single-output (SISO) feedback loops, and one for parameters that require multiple-input-multiple-output (MIMO) realization. The SISO analysis is based on frequency response functions, with the formulation aims at tracking the important flutter mechanisms, and is arranged such that the sensitivity to different parameters, over large variation ranges, may be based on the same set of response functions. The MIMO analysis is similarly effective, but is based on eigensolutions that indicate the parametric changes needed to obtain flutter. Three numerical examples using a generic transport aircraft model are presented, where sensitivity with respect to stiffness and mass variations were studied. The SISO and MIMO approaches are also applied for calculating damping and frequency variations with velocity that may be used as traditional V-g plots in aeroelastic design and certification tasks. The results demonstrate excellent agreement with those obtained by separate MSC/NASTRAN's p-k solutions and nonlinear time marching simulations.
展开▼
