Effect of Modeling Techniques in the Coupled Rotor-Body Vibration Analysis

Vellaichamy, Senthilvel; Chopra, Inderjit

doi:10.2514/6.1993-1360

Cited by 10 publications

(4 citation statements)

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“…14,22,23 Such orderingschemes have been also used in other similar studies involving coupled rotor/ exible fuselage dynamics. 15,16 The ordering scheme is based on the assumption that…”

Section: Rotor Modelmentioning

confidence: 99%

“…Other studies have represented the coupled rotor/ exible fuselage model by a one-dimensional beam, where the beam itself is modeled using a number of discrete beamtype nite elements. 15,16 Again, the important role of nonstructural masses in accurately simulating the frequency content of the coupled rotor/ exible fuselage system was not addressed in Refs. 15 and 16.…”

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confidence: 98%

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Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

2000

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A re ned coupled rotor/ exible fuselage aeroelastic response model is developed for vibration reduction studies based on active control of structural response (ACSR). The structural model is capable of representing exible, hingeless rotors combined with a exible fuselage, and a rigid platform combined with the actuators required for modeling the ACSR system and is combined with a free wake model. The in uence of rotor/fuselage coupling and improved aerodynamics on the vibratory hub loads is investigated. Nomenclature A= beam cross-sectional area a NbC , a Nb S = cosine and sine parts of acceleration at various fuselage locations a z = fuselage vertical acceleration at various locations C d0 = blade drag coef cient C O , C I , C NW = matrices of induced velocity in uence coef cients C W = helicopter coef cient of weight c = blade chord D = wake distortion E = Young's modulus of elasticity E I y , E I z = blade bending stiffnesses in ap and lead-lag= blade aerodynamic, gravitational, and inertial forces F b0 , F bnc , F bns = Fourier coef cients of blade equations of motion F e0 , F enc , F ens = Fourier coef cients of elastic fuselage equations of motion F fus = total fuselage forces F NbC , F Nb S = cosine and sine parts of rotor hub forces F r0 , F rnc , F rns = Fourier coef cients of fuselage rigid body equations of motion F T , M T = tail rotor thrust and moment F x , F y , F z = vibratory hub shear components F 0 , M 0 = constant part of rotor hub loads f C d f = fuselage equivalent at plate drag area G J = blade torsional stiffness [I ] = fuselage inertia tensor I p = polar moment of inertia I x , I y , I z = fuselage beam cross-sectional principal moment of inertia J = beam torsional constant L = Lagrangian M = fuselage total mass M A b , M G b , M I b = blade aerodynamic, gravitational, and inertial moment M fus = total fuselage moments M Nb C , M Nb S = cosine and sine parts of hub moments M ns = nonstructural consistent mass matrix M x , M y , M z = vibratory hub moment components m b = blade mass distribution per unit length N = matrix of shape functions for calculation of nonstructural mass matrix N b = number of blades N H , N el , N rg = number of harmonics retained in Fourier expansion of blade, fuselage elastic, and rigid body degrees of freedom Q i = fuselage generalized force q = response vector q b , q e , q r = vectors of blade, fuselage elastic, and rigid body degrees of freedom q b0 , q bnc , q bns = Fourier coef cients of blade response q e0 , q enc , q ens = Fourier coef cients of fuselage elastic response q r0 , q rnc , q rns = Fourier coef cients of fuselage rigid body response R = rotor radius R x , R y , R z = fuselage rigid body translational degrees of freedom R 0 = fuselage center of mass position in inertial frame r b = position of rotor blade point r w = position of wake element r 0 = undeformed position of fuselage point with respect to the fuselage center of mass in fuselage reference frame r 0 = deformation of fuselage point in fuselage reference frame T = kinetic energy U e = e...

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“…14,22,23 Such orderingschemes have been also used in other similar studies involving coupled rotor/ exible fuselage dynamics. 15,16 The ordering scheme is based on the assumption that…”

Section: Rotor Modelmentioning

confidence: 99%

mentioning

confidence: 98%

Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

2000

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“…However aerodynamic force is ignored in this model. Vellaichamy and Chopra [10] presented a coupled rotor-fuselage analysis using elastic blade and flexible fuselage modeling (stick model). Chiu [11] and Yeo [12] developed coupled rotor/flexible fuselage model for vibration reduction studies using 3-D fuselage.…”

Section: Introductionmentioning

confidence: 99%

A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body

Cheng¹,

Zhu²,

Feng³

et al. 2016

MATEC Web Conf.

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Abstract. To develop a coupled rotor/flexible fuselage model for vibration reduction studies, the equation of coupled rotor-fuselage is set up based on the theory of multi-body dynamics, and the dynamic analysis model is established with the software MSC.ADMAS and MSC.NASTRAN. The frequencies and vibration acceleration responses of the system are calculated with the model of coupled rotor-fuselage, and the results are compared with those of uncoupled modeling method. Analysis results showed that compared with uncoupled model, the dynamic characteristic obtained by the model of coupled rotor-fuselage are some different. The intrinsic frequency of rotor is increased with the increase of rotational velocities. The results also show that the flying speed has obvious influence on the vibration acceleration responses of the fuselage. The vibration acceleration response in the vertical direction is much higher at the low speed and high speed flight conditions.

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“…At present, there are significant contributions to the literature of improving the mathematical modeling and analysis of rotorcraft. A coupled rotor/fuselage based on FEM [31] and FEM-transfer matrix method [32], finite element multibody system [33,34], coupled rotor/fuselage analysis based on elastic blade/flexible fuselage modeling (stick model) [35], and coupled rotor/flexible fuselage model for vibration reduction studies using 3D frame models [36] and using software MSC.ADMAS and MSC. NASTRAN [37] are discussed in detail.…”

mentioning

confidence: 99%

Flapwise Vibration Computations of Coupled Helicopter Rotor/Fuselage: Application of Multibody System Dynamics

et al. 2018

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Natural vibration characteristics of rotating blades are of fundamental importance from the viewpoint of maneuvering, blade life, vibration levels, aeroelastic, and stability. Helicopters may have serious resonant vibration problems when the excitation frequencies are equal to some multiple of the rotational speed. To ensure that conditions susceptible to resonance do not exist within the range of operating speeds, it is necessary that the natural frequencies and mode shapes be determined accurately. On one hand, as the complexity of multibody systems and the methods used for their design and control increases, the need for more elegant formulations of the equations of motion becomes an issue of paramount importance. On the other hand, although processor speed has increased dramatically over the last decade, development of computationally efficient algorithms is still a major issue in multibody dynamics. The transfer matrix method for multibody systems (MSTMM) accounts for both aspects. Based on many advantages of MSTMM in studying multibody system dynamics, a scenario of dynamics coupling between the flexible twin blade rotor and flexible fuselage of a typical helicopter model is proposed. The dynamical model of the coupled system, its topological figure, the overall transfer equation, and the characteristics equation are developed. The flapwise vibrations characteristics are carried out to obtain uncoupled/coupled twin blade/fuselage system natural modes and frequencies as a function of rotor speed. Examples are performed to validate with those published in the literature and produced by Workbench ANSYS.

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Effect of Modeling Techniques in the Coupled Rotor-Body Vibration Analysis

Cited by 10 publications

References 0 publications

Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

Coupled Helicopter Rotor/Flexible Fuselage Aeroelastic Model for Control of Structural Response

A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body

Flapwise Vibration Computations of Coupled Helicopter Rotor/Fuselage: Application of Multibody System Dynamics

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