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RISS 인기검색어
- 검색키워드
- 저자 : Zhencai Zhu (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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A novel energy regeneration system for emulsion pump tests
Li Yilei,Zhu Zhencai,Chen Guoan,Cao Guohua 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4
A novel energy regeneration system based on cylinders and a rectifier valve for emulsion pump tests is presented and studied. The overall structure and working principles of this system are introduced. Both simulation and experiments are carried out to investigate the energy regeneration feasibility and capability of this novel system. The simulation and experimental results validate that this system is able to save energy and satisfy the test requirement. The energy recovery coefficient and overall energy regeneration coefficient of the test bench are 0.785 and 0.214, respectively. Measures to improve these two coefficients are also given accordingly after analysis of power loss. This novel system brings a new method of energy regeneration for emulsion pump tests.
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Nonlinear dynamic response of cable-suspended systems under swinging and heaving motion
Guohua Cao,Naige Wang,Lei Wang,Zhencai Zhu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
In order to enhance the fidelity, convenient and flexibility of swinging motion, the structure of incompletely restrained cablesuspended system controlled by two drums was proposed, and the dynamic response of the system under swinging and heaving motion were investigated in this paper. The cables are spatially discretized using the assumed modes method and the system equations of motion are derived by Lagrange equations of the first kind. Based on geometric boundary conditions and linear complementary theory, the differential algebraic equations are transformed to a set of classical difference equations. Nonlinear dynamic behavior occurs under certain range of rotational velocity and frequency. The results show that asynchronous motion of suspension platform is easily caused imbalance for cable tension. Dynamic response of different swing frequencies were obtained via power frequency analysis, which could be used in the selection of the working frequency of the swing motion. The work will contribute to a better understanding of the swing frequency, cable tension and posture with dynamic characteristics of unilateral geometric and kinematic constraints in this system, and it is also useful to investigate the accuracy and reliability of instruments in future.
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Nonlinear dynamics of rub-impact on a rotor-rubber bearing system with the Stribeck friction model
Chunli Hua,Zhushi Rao,Na Ta,Zhencai Zhu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
Recent experiments on rotor-bearing systems have revealed that three or four different responses may occur when the rubbing occurs. In the present study, a mathematical model is established to investigate the dynamic characteristics of a rotor-rubber bearing system. Theadvantage of this model is demonstrated in the nonlinear stiffness of the rubber bearing and the Stribeck friction model, which generatesfriction force depending on the relative velocity. Through numerical calculation, the effects of rotational speed, the decaying factor, thestiffness coefficient, the nonlinear stiffness coefficient, and the imbalance coefficient on the responses of the rotor-rubber bearing systemare investigated in detail using bifurcation diagrams, orbits of the rotor center, phase plane portraits, Poincaré maps, and amplitude spectra. The obtained numerical simulation results improve understanding on the dynamical characteristics of rub-impact on a rotor-rubberbearing system, such as periodic no-rubbing motion, periodic annular rubbing motion, period-multiplying motion, quasi-periodic motion,dry whip, and the jump phenomenon. These results can be effectively used to diagnose rub-impact faults and instabilities in such rotorsystems. This study may contribute to further understanding on the nonlinear dynamical behavior of rub-impact on rotor-bearing systemswith nonlinear stiffness from the rubber bearing and the Stribeck friction model.
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Coupled bending and torsional vibration of a rotor system with nonlinear friction
Chunli Hua,Guohua Cao,Zhushi Rao,Na Ta,Zhencai Zhu 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6
Unacceptable vibrations induced by the nonlinear friction in a rotor system seriously affect the health and reliability of the rotating machinery. To find out the basic excitation mechanism and characteristics of the vibrations, a coupled bending and torsional nonlinear dynamic model of rotor system with nonlinear friction is presented. The dynamic friction characteristic is described with a Stribeck curve, which generates nonlinear friction related to relative velocity. The motion equations of unbalance rotor system are established by the Lagrangian approach. Through numerical calculation, the coupled vibration characteristics of a rotor system under nonlinear friction are well investigated. The influence of main system parameters on the behaviors of the system is discussed. The bifurcation diagrams, waterfall plots, the times series, orbit trails, phase plane portraits and Poincaré maps are obtained to analyze dynamic characteristics of the rotor system and the results reveal multiform complex nonlinear dynamic responses of rotor system under rubbing. These analysis results of the present paper can effectively provide a theoretical reference for structural design of rotor systems and be used to diagnose selfexcited vibration faults in this kind of rotor systems. The present research could contribute to further understanding on the self-excited vibration and the bending and torsional coupling vibration of the rotor systems with Stribeck friction model.
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