Open Access
Differential equations of motion for combined flapwise bending, chordwise bending, and torsion of twisted nonuniform rotor blades
John C. Houbolt,George W Brooks +1 more
TLDR
In this article, the differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper.Abstract:
The differential equations of motion for the lateral and torsional deformations of twisted rotating beams are developed for application to helicopter rotor and propeller blades. No assumption is made regarding the coincidence of the neutral, elastic, and mass axes, and the generality is such that previous theories involving various simplifications are contained as subcases to the theory presented in this paper. Special attention is given the terms which are not included in previous theories. These terms are largely coupling-type terms associated with the centrifugal forces. Methods of solution of the equations of motion are indicated by selected examples.read more
Citations
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Journal ArticleDOI
Evaluation of Some Flight Safety Aspects of the Single-Engine, Unloaded Rotor, Winged Helicopter
Proceedings ArticleDOI
Entomopter Manoeuvrability Enhancement by Deformations Control of Flexible Flapping Wings
TL;DR: In this article, the authors developed aero-elastic analysis for a flexible wing for an imposed harmonic flapping motion about the root chord of the wing, which was used to find the average lift and thrust of a wing of known aerodynamic and structural properties.
Natural frequency of rotating beams using non-rotating modes
R. G. Loewy,N. Khader +1 more
TL;DR: In this paper, a Lagrangian approach is formulated for predicting the rotating natural frequencies of a beam from the nonrotating modes and frequencies, using the first two non-rotating mode shapes in one case and the first four such modes in the other case.
Journal ArticleDOI
Transonic aeroelasticity analysis for rotor blades
TL;DR: In this paper, a numerical method is presented for calculating the unsteady transonic rotor flow with aeroelasticity effects, where the blade structural dynamic equations based on beam theory were formulated by FEM and were solved in the time domain, instead of the frequency domain.
Improved methods of vibration analysis of pretwisted, airfoil blades
K. B. Subrahmanyam,K. R. V. Kaza +1 more
TL;DR: In this paper, the effects of asymmetry and pretwist on natural frequencies and mode shapes are investigated and the relative merits, convergence properties and accuracies of all four methods are studied and discussed.
References
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Book
Theory of elasticity
TL;DR: The theory of the slipline field is used in this article to solve the problem of stable and non-stressed problems in plane strains in a plane-strain scenario.
Simplified Procedures and Charts for the Rapid Estimation of Bending Frequencies of Rotating Beams
TL;DR: In this paper, a Rayleigh energy approach utilizing the bending mode of the nonrotating beam in the determination of the bending frequency of the rotating beam was presented, which is evaluated and is found to give good practical results for helicopter blades.