Aeroelastic response and stability analysis of composite rotor blades in forward flight

The aeroelastic phenomena of a composite rotor blade are investigated using a finite element method. The aeroelastic equations of motion of the rotor blade are formulated using a large deflection-type beam model that has no artificial restrictions on the magnitudes of displacements and rotations due to the degree of nonlinearity. The sectional elastic constants of a composite box beam including warping deformations are determined from the refined cross-sectional finite element method. The nonlinear, periodic blade steady response is obtained using a time finite element method on full finite element equation. The aeroelastic stability of a rotor blade is investigated by linearizing the dynamics of the rotor blade about the nonlinear equilibrium position. Numerical results of the steady equilibrium deflections and the aeroelastic modal damping are presented for various configurations of composite rotor blades and are compared with those obtained from a previously published modal analysis using a moderate deflection-type beam theory.