Parametric Modeling Of Composite Rotor Blades And The Rotor Dynamics Optimized Method Research

The reduction of the vibration level is one of the most critical problems during the developmentof the helicopter.The dynamic optimization technique is a method to reduce the rotor blade vibratoryloads by the dynamic response design, and the lower vibration level of the airframe can also be givenby the method.The dynamic optimization technique, which is an effective and least costing method, isan important development direction for the helicopter dynamic design and investigation at present.In this paper, based on the rotor blade parametric model, the dynamic optimization method anddesign method for the reduction of vibration are proposed.Some key problems related to methodshave been investigated, and the detailed work of the thesis is presented as following:(1) A model, which is an effective description for the typical rotor blade section, is presented torealize the parametrical modeling of blade aerodynamic shape, internal structural components andphysical characteristics.The automatic meshing method for finite element analysis of the typicalcomposite rotor blade section, properties, is also introduced.The composite box beam and SA-365composite blade are taken as the examples to investigate the blade section property, and the finecorrelation aomong the predicted results, analytical results from the related reference andexperimental data verifies the the parametric method presented in thesis.(2) The nonlinear dynamic model and the calculated method for dynamic response and sectionalvibratory loads are presented to investigate the rotor dynamic optimization.Firstly, based on theHodges moderated deflection rotating beam theory, the fully flap-lag-torsion coupled blade nonlinearcontrol equations are derived.Then, based on the prescribed airloads, three different predictionmethods, which are nonlinear steady-state balance calculation method, steady-state cycle responsecalculation method, as well as the mixed integral method between modaland force., are applied topredict rotor blade vibratory loads.Finally, the nonlinear static deformation, dynamic behaviors andblade sectional vibratory loads are computed and compared with (flight) test data of Princeton beam,three different blade models and SA349/2blade loads, and the methods are effectively verified by thegood agreement between predicted results and test data.(3) The design method for the modal modification to reduce the vibratory loads is developed, andthe multi-objective optimization strategy about the rotor dynamics design is also proposed.Finally,one model rotor and SA349/2rotor are applied to proceed the dynamic optimization with the methodpresented previously, and results show that the vibration level is lowered evidently, the scheme for the optimization is feasible and rotor dynamic optimization method is effectively verified.