Open Access
Natural frequency of rotating beams using non-rotating modes
R. G. Loewy,N. Khader +1 more
TLDR
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.Abstract:
A Lagrangian approach is formulated for predicting the rotating natural frequencies of a beam from the nonrotating modes and frequencies. Using the first two nonrotating mode shapes in one case and the first four such modes in the other case the frequencies of the rotating modes are calculated for a short tapered beam and a typical helicopter blade, respectively. In each case the beam is represented by lumped parameters. The number of mass points representing the beam and the accuracy of the calculated slopes of the nonrotating mode shapes at those points are both shown to affect the accuracy of the resulting frequencies, but the number of stations is shown to be more important.read more
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Structural dynamics of rotating bladed-disk assemblies coupled with flexible shaft motions
R. G. Loewy,Naim Khader +1 more
TL;DR: In this article, a structural dynamics approach is employed to couple the motions of a flexible bladed disk to a rotating flexible shaft, and the analysis accounts for flexible disk displacements which are transverse to the plane of rotation, and radial as well as tangential, and also accounts for rigid disk translations along, and rotations about, axes normal to the undeformed shaft axes.
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Determination of vibration characteristics of multiple-load-path blades by a modified Galerkin's method
D.M. Lauzon,V. R. Murthy +1 more
TL;DR: In this paper, a modified Galerkin's method is developed to determine the natural vibration characteristics of multiple-load-path rotor blades, which follows parallel to the CAMRAD program procedure for a single load-path-blade.
References
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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
TL;DR: 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.
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Free-Vibration Analysis of Rotating Beams by a Variable-Order Finite-Element Method
TL;DR: In this article, the free vibration of rotating beams is analyzed by means of a finite-element method of variable order, where the displacement is assumed to be analytic within an element and thus can be approximated to any degree of accuracy desired by a complete power series.
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Vibrations of Rotating Cantilever Blading: Theoretical Approaches to the Frequency Problem Based on Energy Methods
TL;DR: In this paper, a theoretical expression for the work done due to centrifugal effects when a rotating cantilever blade executes small vibrations is derived, based on previously derived expressions for the stationary blade.
Nonlinear flap-lag-axial equations of a rotating beam with arbitrary precone angle
TL;DR: In this paper, the second-degree nonlinear equations of motion for the coupled flapwise bending, lagwise bending and axial extension of an untwisted, torsionally rigid, nonuniform, rotating beam having an arbitrary angle of precone with the plane perpendicular to the axis of rotation are derived using Hamilton's principle.
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Application of the finite element method to rotary-wing aeroelasticity.
Peretz P. Friedmann,F. K. Straub +1 more
TL;DR: In this paper, a finite element method for the spatial discretization of the dynamic equations of equilibrium governing rotary-wing aeroelastic problems is presented, based on weighted Galerkin residuals.