Influence of torsion on a rub-impact Jeffcott rotor system

Aimed at a Jeffcott rotor system with rigid support, rub-impact force and moment are described, based on Coulomb friction model. And the nonlinear differential equations of coupled bending and torsional vibration of a rubbing rotor is established.. Then, the numerical analysis is accomplished. The data generated,are displayed graphically and explained with the aid of the theory of modem nonlinear dynamics. The influence of torsion on rub-impact rotor is studied, in details, and the important differences of system response of two motions, one is with torsion and the other without torsion, are given. By the bifurcation diagrams of the change of rotating speed, it is discovered that there are apparent differences between two motions. They all possess complex chaotic motions and bifurcation phenomena besides periodic and quasi-periodic vibrations, but the paths to enter and leave the complex motions are different. By the bifurcation diagrams of the change of torsional damping coefficient, it is discovered that the motion is strongly influenced by the torsional damping coefficient. With the increase of the coefficient, the characteristics of the system change complexly. Nonlinear vibration characteristics revealed in this paper are of great significance to the condition monitoring and diagnosis of the rotor system.