Helicopter rotor-fuselage aeroelasticity modeling and solution using the partition-iteration method

This paper seeks to outline a novel coupled helicopter rotor-fuselage model and a new partition-iteration solution philosophy to predict structural response and rotor blade vibration loads. Based on a two-dimensional quasi-steady aerodynamics model, non-inertial coordinates and beam element with five nodes and 15 degrees of freedom (dofs) are first used to establish the aeroelastic differential equations of rotor blade vibration motion to describe exactly various inhomogeneities of the rotor blade including the longitudinal variation of its axial force. Three rigid body freedoms are subsequently allowed at the root of the rotor blade to describe the different hub connections, through which, the mixed truss girder-beam model of the fuselage structure is combined with the aeroelastic model of the rotor blade and the helicopter coupled rotor-fuselage model is established. The new partition-iteration solving philosophy is developed to allow solution of the periodic response of the nonlinear coupled multi-freedom dynamic system. Finally, the new model and its solution were used to compute some vibration loads of a helicopter model, and the obtained results have a good agreement with those of previous works.