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On forward and backward precession of rotors

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Summary

A study of the excitation of backward and forward precessional motion of rotors is presented. It is shown that if the rotor is supported in bearings with rotational symmetry, a rotating unbalance of the shaft cannot excite backward precessions, but if the bearings have even the slightest anisotropy, backward synchronous precessions are excited just as in the case of forward precessional motions. However, internal damping forces have a marked effect in reducing the amplitudes of the backward precessions.

A rotating unbalanced non-uniform continuous circular shaft supported by anisotropic flexible bearings is studied. The governing equations of motion are derived taking into account the effects of transverse shear, gyroscopic moments, and internal and external damping.

Übersicht

Es wird die Erregung der gleich- und gegen-läufigen Präzessionen von Rotoren untersucht. Es wird gezeigt, daß bei Rotoren in rotationssymmetrischen Lagern eine Unsymmetrie der Welle keine gegenläufigen Präzessionea verursachen kann. Bei der geringsten Anisotropie der Lagerung werden jedoch synchrone gegenläufige Präzessionen in derselben Weise wie die gleichläufigen Präzessionen erregt. Allerdings werden die gegenläufigen Präzessionen durch innere Dämpfungskräfte stärker reduziert.

Es wird weiterhin eine unwuchtige Welle mit nicht-konstantem Kreisquerschnitt untersucht, die in anisotropen, nachgiebigen Lagern gelagert ist. Die Bewegungsgleichungen werden für diesen Fall unter Berücksichtigung der Querkräfte, der Kreiselmomente und der inneren und äußeren Dämpfung abgeleitet.

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Authors and Affiliations

  1. Department of Solid Mechanics, The Technical University of Denmark, DK-2800, Lyngby, Denmark

    P. T. Pedersen

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  1. P. T. Pedersen
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Additional information

The author is indebted to Professor Frithiof I. Niordson for many valuable comments on the present paper.

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Pedersen, P.T. On forward and backward precession of rotors. Ing. arch 42, 26–41 (1972). https://doi.org/10.1007/BF00533283

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  • DOI: https://doi.org/10.1007/BF00533283

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