Dynamic Instability of Beams Under Tip Follower Forces Using Geometrically Exact, Fully Intrinsic Equations

Amoozgar, Mohammadreza; Shahverdi, Hossein

doi:10.1590/1679-78253010

Cited by 11 publications

(4 citation statements)

References 46 publications

(44 reference statements)

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“…The overall dynamics of the composite hingeless rotor blade is simulated by the geometrically exact fully intrinsic beam equations [30], which has been used successfully to model beam-like structures [31][32][33][34][35]. These equations…”

Section: Formulationmentioning

confidence: 99%

Lag-twist coupling sensitivity and design for a composite blade cross-section with D-spar

Amoozgar

Shaw

Zhang

et al. 2019

Aerospace Science and Technology

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In this paper, the effect of various parameters of a specific rotor blade cross-section on the effectiveness of a twist morphing concept is investigated. Then, by considering different constraints, a cross-section consistent with this morphing concept with high lag-twist coupling and low extension-twist, is developed. This lag bending-torsion coupling is used to change the twist of the blade during the flight, while the high values of extension-twist coupling is avoided. To this end, a concentrated mass is added to the blade, where its chordwise location varies in flight. When the mass moves in the chordwise direction, a local lag bending is introduced into the blade. This in-plane bending moment then changes the blade twist distribution through lag-twist coupling induced through stiffness tailoring in the blade cross-section. Therefore, this coupling plays an important role in this morphing concept. The one-dimensional dynamics of the blade is modelled by using the geometrically exact fully intrinsic bean equations while the 2D crosssectional stiffness values are determined by using the VABS software. First, a blade which resembles the BO-105 main rotor blade in the fundamental frequencies is designed. Then, the effect of various parameters of the crosssection on the fundamental frequencies, the lag-twist coupling, and the extension-twist coupling are determined. It is found that the skin of the spar has the highest contribution to both the extension-twist and the lag-twist coupling. Finally, a cross-section compatible with the proposed morphing concept is designed and it is demonstrated that the twist of the blade may be changed significantly.

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Section: Formulationmentioning

confidence: 99%

Lag-twist coupling sensitivity and design for a composite blade cross-section with D-spar

Amoozgar

Shaw

Zhang

et al. 2019

Aerospace Science and Technology

View full text Add to dashboard Cite

show abstract

“…They found that the GDQ method can obtain more accurate results with a lesser computational cost than the traditional finite element method. Based on GDQ method, they also analyzed the dynamic stability of the beam under following forces [30] and the aeroelastic stability of the hingeless rotor [31]. Tashaorian et al [16] used the GDQ method for the spatial discretization of non-local fully intrinsic equations.…”

Section: Introductionmentioning

confidence: 99%

Differential Quadrature Method for Fully Intrinsic Equations of Geometrically Exact Beams

Chen

Liu

2022

Aerospace

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In this paper, a differential quadrature method of high-order precision (DQ−Pade), which is equivalent to the generalized Pade approximation for approximating the end of a time or spatial interval, is used to solve nonlinear fully intrinsic equations of beams. The equations are a set of first-order differential equations with respect to time and space, and the explicit unknowns of the equations involve only forces, moments, velocity and angular velocity, without displacements and rotations. Based on the DQ−Pade method, the spatial and temporal discrete forms of fully intrinsic equations were derived. To verify the effectiveness and applicability of the proposed method for discretizing the fully intrinsic equations, different examples available in the literatures were considered. It was found that when using the DQ−Pade method, the solutions of the intrinsic beam equations are obviously superior to those found by some other usual algorithms in efficiency and computational accuracy.

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“…The stability of cantilever beams subjected to uniformly distributed non-conservatives was investigated by Fazelzadeh and Kazemi-Lari [5]. Amoozgar and Shahverdi [6] studied the effect of non-conservative forces on the dynamic stability of isotropic blades using exact beam theory. They showed that the blade rotating speed and direction of the force significantly change the dynamic behavior of the blade.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Non-Conservative Compressive Force on the Vibration of Rotating Composite Blades

2020

Self Cite

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This paper investigates the effectiveness of a resonance avoidance concept for composite rotor blades featuring extension–twist elastic coupling. The concept uses a tendon, attached to the tip of the blade, to apply a proper amount of compressive force to tune the vibration behavior of the blade actively. The tendon is simulated by applying a non-conservative axial compressive force applied to the blade tip. The main load carrying part of the structure is the composite spar box, which has an antisymmetric layup configuration. The nonlinear dynamic behavior of the composite blade is modelled by using the geometrically exact fully intrinsic beam equations. The resulting nonlinear differential equations are discretized using a time–space scheme, and the stationary and rotating frequencies of the blade are obtained. It is observed that the proposed resonance avoidance mechanism is effective for tuning the vibration behavior of composite blades. The applied compressive force can shift the frequencies and the location at which the frequency veering take place. Furthermore, the compressive force can also cause the composite blade to get unstable depending on the layup ply angle. Finally, the results, highlighting the importance of compressive force and ply angle on the dynamic behavior of composite blades, are presented and discussed.

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Dynamic Instability of Beams Under Tip Follower Forces Using Geometrically Exact, Fully Intrinsic Equations

Cited by 11 publications

References 46 publications

Lag-twist coupling sensitivity and design for a composite blade cross-section with D-spar

Lag-twist coupling sensitivity and design for a composite blade cross-section with D-spar

Differential Quadrature Method for Fully Intrinsic Equations of Geometrically Exact Beams

The Effect of Non-Conservative Compressive Force on the Vibration of Rotating Composite Blades

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