Dynamic Behavior Of Rotor-bearing System Research Articles

Experimental investigation of dynamic behavior of rotor-bearing system with nitrile rubber support

Nitrile rubber (NBR) as a vibration absorber of lower elasticity modulus has a considerable contribution in the effective damping. Three kinds of journal bearings (general journal bearings, journal bearings supported on circular nitrile rubber, journal bearings supported on radial nitrile rubber) were designed and manufactured. Experiments were carried out to investigate vibration and stability of the rotor-bearing system with the above bearings. Oil whirl and the onset of instability of the system was analyzed and compared. The experimental results show that there is a significant decrease in the acceleration amplitude of the bearings embedded with nitrile rubber compared to general journal bearings. In addition, the journal bearings supported on radial nitrile rubber have better vibration damping effect than journal bearings supported on circular nitrile rubber, for there is no obvious oil whirl and asynchronous vibration, which can be verified by waterfall plots and continuous wavelet transform spectrograms. Results demonstrated that vibration energy dissipated by viscous absorbers indeed contributes to improving dynamics stability of the rotor-bearing system.

Experimental Analysis of Rotor-Bearing System for Fault Detection

Rotating system is a main part in any industry. The design of such systems in modern engineering is towards lower weight operating at super critical speed for longer periods of time. In actual working condition, faults are unavoidable due to the error in manufacturing; faults may develop in the system due to the operating conditions such as heat generation, unbalance, wear, misalignment, looseness etc. In this study, dynamic behavior of rotor-bearing system is studied. This model mainly represents the driving unit at industrial machine applications. Disc at the model can be considered as gear or pulley, etc .at the transmission line. Experimental vibration analyses in vertical direction of the system are implemented. Vibration monitoring with Run up measurement analysis and Spectrum graphs are used to diagnose the excessive vibration source. It is seen that vibration at the rotor-bearing system not only one faults but also combination of several faults such as unbalance, wear, misalignment, looseness, etc. A non- destructive evaluation method for left & right bearing is used to diagnose the undue vibration source before it become critical.

Robust optimal design of the FDBs in a HDD to reduce NRRO and RRO

This research proposes a robust optimal design methodology of the FDBs in a HDD to reduce RRO and NRRO. The critical mass, which determines the dynamic behavior of rotor-bearing system, was selected as an objective function, and the constraint equations were the friction torque of the FDBs, and the stiffness and damping coefficients related with under-damped vibration modes. Ten major design variables of the FDBs were chosen in this optimization problem. The steady-state whirl radius and the shock response at half-speed whirl of the rotating rigid spindle-bearing system were evaluated as RRO and NRRO, respectively. RRO and NRRO of the optimal design were compared with those of conventional one, and it showed that the proposed method could effectively reduce RRO and NRRO.