Abstract
This paper presents a finite element model of a rotor system with pedestal looseness stemming from a loosened bolt and analyzes the effects of the looseness parameters on its dynamic characteristics. When the displacement of the pedestal is less than or equal to the looseness clearance, the motion of the rotor varies from period-one through period-two and period-three to period-five with the decreasing of stiffness of the non-loosened bolts. The similar bifurcation phenomenon can be also observed during the increasing process of the rotational speed. But the rotor motion is from period-six through period-three to period-four with the decreasing of the foundation stiffness. When the stiffness of the foundation is small and the displacement of pedestal is greater than the looseness clearance, the response of the rotor exhibits period-one and high order harmonic components with the decreasing of looseness clearance, such as 2X, 3X etc. However, when the stiffness of the foundation is great, the spectrum of the response of the rotor will be from combined frequency components to the continuous spectrum with the decreasing of the looseness clearance.
Highlights
In a rotor-bearing system, the loosened bolt of the pedestal will reduce pedestal stiffness, mechanical damping, which results in violent vibration of the whole system
This paper investigates the dynamic characteristics of a rotor system with pedestal looseness
In the following we investigate the dynamic characteristics of rotor system with pedestal looseness when yb δ1
Summary
In a rotor-bearing system, the loosened bolt of the pedestal will reduce pedestal stiffness, mechanical damping, which results in violent vibration of the whole system. Goldman and Muszynska [3] proposed the bilinear model of a rotating machine with one loose pedestal Their numeric results showed the synchronous and subsynchronous fractional components of the response, which were verified by the experiments. Chu and Tang [5] analyzed vibration characteristics of a rotor-bearing system with pedestal looseness by building a non-linear mathematical model. Stability of these periodic solutions was discussed by using the shooting method and the Floquet theory.
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