Composite rotor blade design optimization for vibration reduction with aeroelastic constraints

The paper presents an analytical study of the helicopter rotor vibratory load reduction design optimization with aeroelastic stability constraints. The composite rotor blade is modeled by beam type finite elements, and warping deformation is taken into consideration for 2-dimension analysis, while the one-dimension nonlinear differential equations of blade motion are formulated via Hamilton's principle. The rotor hub vibratory loads is chosen as the objective function, while rotor blade section construction parameter, composite material ply structure and blade tip swept angle as the design variables, and autorotation inertia, natural frequency and aeroelastic stability as the constraints. A 3-bladed rotor is designed , as an example, based on the vibratory hub load reduction optimization process with swept tip angle and composite material. The calculating results show a 24.9%-33% reduction of 3/rev hub loads in comparison with the base-line rotor.