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Vibratory synchronization transmission of two exciters in a super-resonant vibrating system
Xueliang Zhang,Bang-chun Wen,Chunyu Zhao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6
In this study, vibratory synchronization transmission (VST) of two exciters is investigated in a super-resonant vibrating system to saveenergy. First, the frequency capture equation of two exciters (FCETE) is deduced by the average method of small parameters. The criterionof VST being the equivalent effective residual torque of motor with power supply should be smaller or equal to the frequency capturetorque of the system by setting the disturbance parameters of angular velocities in FCETE to zero. The stability criterion of synchronousstates is derived by complying with the generalized Lyapunov equations. Lastly, experiment and computing simulation on VST areconducted. The VST regime of two exciters is discussed in detail from coupling characteristic, current change, visual picture, phase relation,and direct verification of parameters, respectively by comparison and analyses of corresponding data. Results indicate that the keyfactor in VST implementation is the torque of frequency capture, which serves as the ‘vehicle’ in transferring energy. Thus, the distancebetween rotational centre of each exciter and mass centre of the rigid frame should be far enough to enhance the ability of VST and ensureenergy saving. The theory, experiment, and computing simulation prove that the theoretical approach used in this study is useful and feasible.
A tunable dynamic vibration absorber for unbalanced rotor system
Hongliang Yao,Tongzhao Wang,Bang-chun Wen,Baijun Qiu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
A tunable dynamic vibration absorber for unbalanced rotor system which is made up of coil springs and magnetic spring is presented. The structure of the absorber is introduced and the stiffness tuning mechanism of the magnetic spring is explained. A finite element model of the rotor-absorber system was built and the influencing factors to the appearance of the absorber were studied numerically. Finally, experiments were carried out to verify the numerical results, and PID control strategy was tested. The numerical and experimental results show that the present absorber is effective for vibration suppression of an unbalanced rotor system, and the control strategy is effective.
Effects of different coupling models of a helical gear system on vibration characteristics
Qibin Wang,Zhanwei Li,Hui Ma,Bang-chun Wen 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5
Time-varying mesh stiffness (TVMS) and the dynamic coupling between the helical gears have a great influence on the vibration characteristics of a helical gear rotor system. Considering the effects of TVMS and adopting two coupling models (lateral-torsional coupling model and lateral-torsional-axial-swing coupling model), the dynamic behavior of a helical gear system was studied. First, an analytical model was used to analyze TVMS of a helical gear pair where the helical tooth is simulated by many spur tooth slices along the direction of the tooth width and the mesh stiffness of each slice is calculated using the energy method. Then, considering the effects of the TVMS excitation, the finite element model of a helical gear rotor system was established. Gear mesh was simulated by the above-mentioned two coupling models to investigate the effects of coupling forms on the system vibration characteristics. The strain energy was used to distinguish the dominant mode and dominant shaft of a gear system in natural characteristics analysis. The results show that the full coupling model can analyze accurately the vibration characteristics of the system and the axial and swing motions cannot be ignored in vibration analysis. Finally, the effects of helix angle on TVMS and vibration responses of a helical gear system were also studied.
Prediction method for steady-state response of local rubbing blade-rotor systems
Qian Zhao,Hongliang Yao,Qi Xu,Bang-chun Wen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.4
Blade-rotor systems frequently encounter the problem of blade-to-case rubbing, which affects their safety and stability. Numericalsimulation can be used to predict the steady-state response of these systems. However, such simulation is frequently computationallyexpensive because of the high dimensions of the dynamic model of a blade-rotor system. To overcome this problem, a new method thatcombines the receptance-based dimension-reduction approach with the incremental harmonic balance (IHB) method is presented in thisstudy. First, a dynamic model of a blade-rotor system is developed using the finite element method, and the number of dimensions of themodel is reduced by the receptance method. Subsequently, the steady-state response is obtained by the improved IHB method to convenientlymanage the large number of super-harmonic components of the local rubbing system. Finally, the precision and efficiency of theproposed method is verified by comparing its results with those obtained by the Newmark-b method. The proposed method is found to beefficient in analyzing local rubbing blade-rotor systems with high dimensions, local nonlinearities, and rich super-harmonics.
Vibration control of rotor system by ultrasonic excited limiter
Hongliang Yao,Qian Zhao,Hao Wu,Bang-chun Wen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
We propose a novel method with an ultrasonically excited structure as a vibration limiter to control the vibration of rotor systems. Thefriction between the rotor and the limiter is significantly reduced by ultrasonic lubrication, thereby preventing the occurrence of rubbinginducedthermal bowing, which is commonly observed in traditional vibration limiters. In our study, the friction reduction mechanism ofthe ultrasonically excited vibration limiter was first examined based on tribology theory and Hertz contact theory. The vibration controleffects and the alleviation of thermal bowing were then investigated by numerical simulation. Finally, vibration control experiments wereperformed on a Bentley test rig with the ultrasonically excited vibration limiter. The consistency between theoretical and experimentalresults confirmed the effectiveness of the proposed method.