An experimental rotor rig was developed to investigate nonlinear vibration characteristics of rotor bearing system with coupling fault of rub-impact and oil whirl. It was found that when the effect of oil film force on a rub-impact rotor system is comparatively weak, the rotor/stator rub-impact will cause the system to give rise to sub- and super-harmonic vibration components. In a rub-impact rotor system with oil whirl fault, super-harmonic vibration components were excited, when rotor/stator rub-impact happens before oil film whirl because of small rotor/stator clearance. When the rotor/stator clearance is comparatively large, the rub-impact happens after oil film whirl, and the effect of rub-impact on the rotor system will be very weak.
The vibration characteristics of the structure are important parameters of structural design if want to accurately grasp the vibration characteristics of the structure, the testing methods must be proper. At the present time, pulsation, free vibration, vibrating load are the common methods, This article adopts pulsation, knocking, initial displacement, white noise sweeping, and simple harmonic waves knocking to test the vibration characteristics of the structure and studies the characteristics of those testing methods.
When agricultural machines are operated on pavements, the lug excitation force occurring on a rolling agricultural tire is primary cause of the vibration. Therefore, it is important to investigate the lug excitation force in order to clarify the vibration generation mechanism. In our previous study, it is considered that the dynamic behavior of a rolling agricultural tire is influenced by the vibration characteristics of the tire. Further, only the rigid modes among the natural modes could affect the rolling tire behavior. So, we modeled the tire as a circular rigid ring supported on an elastic foundation with contact model. This rigid ring model can be valid to investigate the lug excitation force, while it is necessary to measure forces acting on tire shaft in order to estimate the lug excitation force. In this study, the test equipment is modified to measure tire shaft forces at rolling, by improved supporting structure equipped with 6-component force transducers and the shaft force characteristics are investigated. It is confirmed that the vibration characteristics of the tire influence the shaft force characteristics.
The vibration characteristics of the transformer winding calculation and experimental research