Aeroelastic Analysis of a Composite Material Delta Wing in Low Subsonic Flow

An experimental and computational study of the flutter and limit cycle oscillations of a three-layer carbon-fiber composite material 45 deg delta wing is presented. The computational aeroelastic model uses a set of nonlinear structural dynamics (modal) equations that are coupled to a vortex-lattice aerodynamic model. The nonlinear modal equations for the structure are formulated using a system identification methodology. To reduce the computational time needed in the computation of the strain energy needed to construct the reduced-order structural dynamics model, a new algorithm that uses a Smolyak sparse-grid technique is proposed to perform the sampling of strain energy data used for generation of the equations of motion. Experiments and computations are performed, and compared, for a number of layup configuration angles. The qualitative agreement between experimental flutter and limit cycle results is good, with both sets of results displaying similar trends with respect to variations in layup angle and a nondimensional parameter, which gives a measure of the bending torsion coupling in the laminate.