The nonlinear bending stiffness of a rod-fastened rotor varies with the applied loads to significantly influence the dynamic characteristics. In this paper
cubic and bi-linear models are both adopted to perform a comparative analysis on the nonlinear dynamic characteristics of a rod-fastened rotor system. First
the bending stiffness of the rod-fastened rotor system with two disks is obtained using a 3D FEM model. Then
a cubic stiffness model is applied to approximate the nonlinear stiffness
and subsequently the corresponding governing equation is derived. The harmonic balance method(HBM)and iterative optimization method based on Broyden algorithm are adopted to get the steady-state response. Besides
the influences of different parameters on rotor dynamics are further investigated. Finally
a bilinear stiffness model is utilized to conduct the comparative analysis on the dynamic response of the rod-fastened rotor system. The results show that both models can be used to demonstrate the amplitude jump behavior of the rotor system. However
these two models have different explanations on amplitude jump
so that the dynamic characteristics are different near the unstable region
and the cubic model has a more abundant nonlinear behavior than that of the bi-linear model. The results also show that
by adjusting the nonlinear system parameters
the position of the unstable region in the amplitude-frequency response curve can be changed
thereby effectively preventing the rotor system from operating in an unstable frequency region.
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references
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