Aeroelastic analysis of bearingless rotors with a composite flexbeam

Lim, In-Gyu; Lee, In

doi:10.1016/j.compstruct.2008.06.007

Cited by 9 publications

(3 citation statements)

References 28 publications

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“…Lim and Lee [114] discretized the composite flexible beam into beam elements in order to investigate the effects of the arbitrarily large displacement and rotation. The number of DOF of FEM descretization is much higher than that of the former method, which means it will cost more computational time for each time step.…”

Section: Discretization To 1d Equivalent Beam Modelmentioning

confidence: 99%

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Zhang

Huang

2011

Front. Energy

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Aeroelasticity has become a critical issue for Multi-Megawatt wind turbine due to the longer and more flexible blade. In this paper, the development of aeroelasticity and aeroelastic codes for wind turbine is reviewed and the aeroelastic models for wind turbine blade are described, based on which, the current research focuses for large scale wind turbine are discussed, including instability problems for onshore and offshore wind turbines, effects of complex inflow, nonlinear effects of large blade deflection, smart structure technologies, and aerohydroelasticity. Finally, the future development of aeroelastic code for large scale wind turbine: aeroservoelasticity and smart rotor control; nonlinear aeroelasticity due to large blade deflection; full-scale 3D computational fluid dynamics (CFD) solution for dynamics; and aerohydroelasticity are presented.

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Section: Discretization To 1d Equivalent Beam Modelmentioning

confidence: 99%

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Zhang

Huang

2011

Front. Energy

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“…The analysis showed that the non-classical couplings affect the aeroelastic stabilities, and therefore must be considered in general purpose analysis. Lim and Lee [27] studied the aeroelastic analysis of bearingless rotor blades considering a composite flexbeam by using a large deflection beam theory. They showed that the bending-torsional coupling of the composite layup could change the stability of the lag mode.…”

Section: Introductionmentioning

confidence: 99%

The effect of a movable mass on the aeroelastic stability of composite hingeless rotor blades in hover

Amoozgar

Shaw

Zhang

et al. 2019

Journal of Fluids and Structures

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In this paper, the aeroelastic stability of a composite hingeless rotor blade with a chordwise movable mass is investigated. The point mass is located near the tip of the blade and its chordwise location is variable with respect to the elastic axis and can be moved during the flight. This movable mass is added to the blade to actuate the blade twist during flight. By actuating the mass in the chord direction of the blade during the flight, a bending moment which is the result of the centrifugal force of the mass and its offset is induced on the blade. This bending moment induces twist in the blade, due to bend-twist coupling in the composite lamination. The blade is modelled by using the geometrically exact fully intrinsic beam equations along with the variational asymptotic beam sectional analysis. The aerodynamic loads are simulated by using the two-dimensional strip theory combined with a uniform inflow. The nonlinear partial differential aeroelastic equations are discretized by a time-space scheme, and the converged results are compared with those reported in the literature and a very good match is observed. The results show that by positioning the mass near the tip of the blade, and also by using the ply angle of about 30 degree in this configuration, the highest possible twist change is achieved when the mass moves from the leading edge to the trailing edge of the blade. Moreover, the spanwise location of the mass slightly changes the stability boundaries, while the chordwise movement significantly affects the aeroelastic instability.

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“…An aeroelastic analysis of bearingless rotors is investigated using large deflection beam theory in hover and forward flight. The sectional elastic constants of a composite flex beam, including the warping deformations, are determined from a refined cross-sectional finite element method (Lim and Lee 2009). A new finite element model based on the coupled displacement field and the tapering functions of the beam is formulated for transverse vibrations of rotating Timoshenko beams of equal strength (Yardimoglu 2010).…”

Section: Introductionmentioning

confidence: 99%

Preparation of bi-polar membranes and their application to hypochlorite production

Kim¹,

Cho²,

Rhim³

et al. 2015

Membr. Water Treat.

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Flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. This includes aircraft, helicopter blades, engine rotors, buildings and bridges. Flutter occurs as a result of interactions between aerodynamic, stiffness and inertia forces on a structure. The conventional method for designing a rotor blade to be free from flutter instability throughout the helicopter's flight regime is to design the blade so that the aerodynamic center (AC), elastic axis (EA) and center of gravity (CG) are coincident and located at the quarterchord. While this assures freedom from flutter, it adds constraints on rotor blade design which are not usually followed in fixed wing design. Periodic Structures have been in the focus of research for their useful characteristics and ability to attenuate vibration in frequency bands called "stop-bands". A periodic structure consists of cells which differ in material or geometry. As vibration waves travel along the structure and face the cell boundaries, some waves pass and some are reflected back, which may cause destructive interference with the succeeding waves. In this work, we analyze the flutter characteristics of a helicopter blades with a periodic change in their sandwich material using a finite element structural model. Results shows great improvements in the flutter forward speed of the rotating blade obtained by using periodic design and increasing the number of periodic cells.

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Aeroelastic analysis of bearingless rotors with a composite flexbeam

Cited by 9 publications

References 28 publications

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

Review of aeroelasticity for wind turbine: Current status, research focus and future perspectives

The effect of a movable mass on the aeroelastic stability of composite hingeless rotor blades in hover

Preparation of bi-polar membranes and their application to hypochlorite production

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