Abstract

The new method of the forced resonance vibrations construction in mechanical systems with internal resonance is represented. According to this approach, the generalized theory of non-linear normal vibration modes by Shaw and Pierre, the modified Rauscher method and the harmonic balance method are combined with a new iterative computation procedure.The proposed approach is used in analysis of the single-disk rotor system with the isotropic-elastic shaft and the non-linear supports of Duffing type. Gyroscopic effects, asymmetrical disposition of the disk on the shaft and internal resonance are also taken into account. The NNM approach allows reducing the 8-DOF problem of the rotor dynamics to the 2-DOF non-linear system for each non-linear normal mode. Both the model of massless supports and the model of supports with inertial effects are considered. It is shown that in last case all resonance regimes are separated into two different kinds. First kind corresponds to cyclic symmetric trajectories in a system's configuration space; the second kind corresponds to centrally symmetric ones. Regimes of the first kind can be evaluated by the use of the simplified mathematical model proposed in this work. Simplified model consists only of four generalized coordinates instead of the eight initial ones.

Highlights

  • Non-linear normal vibrations modes (NNMs) are a generalization of the normal vibrations in linear systems

  • Two principal concepts of nonlinear normal vibrations modes were developed by Kauderer and Rosenberg (NNMs in conservative systems) and by Shaw and Pierre (NNMs in dissipative systems)

  • Results obtained by the NNMs method, the harmonic balance method, and the verifying numerical simulation, are compared

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Summary

Introduction

Non-linear normal vibrations modes (NNMs) are a generalization of the normal vibrations in linear systems. The non-linear normal modes (NNMs) are constructed here for the rotor systems with the internal resonance This situation is always realized in the rotor dynamics with the isotropic-elastic shaft and the isotropic-elastic supports. The procedure described is intended to obtain solutions describing forced near-resonance steady-state vibrations of mechanical systems It is iterative and combines the NNMs, Rauscher, and harmonic balance methods. Note that the NNMs are constructed in the form of polynomials of the third degree

Principal model of the rotor dynamics
Forced vibration modes of the rotor on massless supports
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Use of the model having half dimension
Simplification of the NNMs determination
Conclusions
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