Simulation of rotor’s axial rub-impact in full degrees of freedom
Zhenwei Yuan a,b,*, Fulei Chu a, Rujiang Hao a
a Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China
b School of Chemical Engineering, Zhengzhou University, Zhengzhou 450002, China
Received 1 October 2005; received in revised form 16 July 2006; accepted 19 July 2006
Abstract
Axial rub-impact problem scarcely discussed in the previous literature is investigated based on a full-degree-of-freedom
Jeffcott rotor. An axial rub-impact force model corresponding to all the six degrees of freedom is developed according to
Coulomb’s friction law. A rotordynamic model of a rotor with unbalances and axial rub-impact is established using
Lagrangian equation, with the integration of the axial rub-impact force model into it. The dynamic responses are obtained
using ODE solvers in MATLAB. The dynamic behaviors of the rotor are demonstrated by means of waveforms, frequency
spectrums, orbit trails, Poincare maps, and bifurcation diagrams. It is concluded that the dynamic behaviors of axial rubimpact
are quite distinct from those of radial ones, and that the dynamic behaviors of axial vibration are essential to the
diagnostics of axial rub-impact. In addition, an internal bending–torsion coupling phenomenon is disclosed.
 2006 Elsevier Ltd. All rights reserved.