Background: When an unbalanced flexible rotor passes through its critical speed, it is very
easy to result in great vibration amplitude, even the destruction of rotor and bearings. Therefore, it is
significant for high-speed rotating machines to reduce the vibration amplitude of flexible rotor. Various
patents have been discussed in this article.
Objective: The purpose of this study is to find out the amplitude reduction method and simulate the
feasibility of flexible rotor passing through critical speed.
Methods: On the basis of the model of single disk rotor system with eccentric mass, a novel method is
presented to reduce the vibration amplitude passing through critical speed by modulating the acceleration
and stiffness simultaneously. Firstly, the amplitude characteristic of a flexible rotor with different
acceleration and supporting stiffness was investigated. Then, the method of changing the stiffness during
variable acceleration was carried out by numerical simulation based on Newmark algorithm. Furthermore,
the strain energy of rotor and input power were also analyzed by using the method of simultaneous
modulation of acceleration and stiffness.
Results: The simulation results revealed that the simultaneous modulation of acceleration and stiffness
could reduce the vibration amplitude of rotor effectively, which was reduced by 44% and 13%,
comparing with the single variable acceleration and the single variation of stiffness, respectively.
Moreover, the variation tendency of total energy was similar to that of the rotor amplitude, which could
be controlled at a very small level. The input power was mainly dependent on the acceleration, but had
very little to do with the stiffness.
Conclusion: The method was suitable for the model of single disk rotor system, and it could also be
applied to complex rotor systems, which was very useful for the security of high speed rotating machine.