Vibration Dissipation Characteristics of Symmetrical Piezoelectric Networks With Passive Branches

2012 ◽  
Author(s):  
Yu Fan ◽  
Lin Li
Keyword(s):  
Dynamic Models ◽  
Vibration Suppression ◽  
Vibration Reduction ◽  
Design Guidelines ◽  
Connection Form ◽  
Network Connection ◽  
Lumped Parameter ◽  
The Given ◽  
Parameter Approach ◽  
Better Than

In this paper, a new vibration reduction approach by means of symmetric piezoelectric network is proposed, combining energy harvesting and vibration reduction. The system could be constructed by several individual structures with identical mechanical parameters, such as blades of rotor machinery. Two basic forms of network-connection are studied, in which dissipation of both mechanical and electric field is considered. Dynamic models are established by the Lumped Parameter approach and Kirchhoff’s Circuit Theorem, and the normalizing process is used to make the models more general. Subsequently, the modal information and harmonic response of piezoelectric networks with an arbitrary number of components are obtained. Based on the dynamic characteristics of piezoelectric networks, the mechanism of vibration-suppression behavior of such systems is studied. Design guidelines of these vibration reduction systems are established via parameter studies. Eventually, the optimized parameters of each network-connection form are obtained analytically. It is shown that the symmetric piezoelectric network can suppress the response of the given frequency to zero, and also perform better than pure passive piezoelectric shunts in resonant frequency band.

Research on Suppressing Vibration of Mistuning Cyclic-Periodic Structure

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengcheng Deng ◽  
Lin Li ◽  
Chao Li
Keyword(s):  
Periodic Structure ◽  
Vibration Suppression ◽  
Vibration Reduction ◽  
Element Model ◽  
Lumped Parameter Model ◽  
Modal Assurance Criterion ◽  
Suppression Effect ◽  
Lumped Parameter ◽  
Two Systems ◽  
Aero Engines

Abstract This paper deals with the cyclic-periodic structure with piezoelectric shunt circuits or a parallel piezoelectric network. The objective is to obtain the vibration suppression effect of them on the cylic-periodic structure. The background of the research is about vibration reduction of bladed disks in aero-engines, and the system is simulated by a lumped parameter model. The tuned and mistuned dynamic equations of the system are derived. The method of equivalent blisk model (EBM) is used to identify the lumped parameters of a finite element model, which is related to the experimental model. Then the Modified Modal Assurance Criterion (MMAC) is used to evaluate the vibration suppression ability of shunt circuits and the network. The numerical results show that both of these two systems can control vibration well, even the mechanical and electrical mistuning level are up to 10 %, and there is an optimal resistance which can be used to design the system to get a good performance of vibration suppression. An experiment is performed to validate the analytical results. The experimental results demonstrate that the ability of vibration suppression for both two systems are almost the same, but the piezo-network has an advantage in vibration delocalization of the mistuned system.

Sinai and Exodus: Two Grounds for Hope in the Jewish Tradition

1978 ◽  
Vol 14 (3) ◽  
pp. 373-387
Author(s):  
David Hartman
Keyword(s):  
Jewish Tradition ◽  
Look Ahead ◽  
The World ◽  
The Future ◽  
Sole Criterion ◽  
The Given ◽  
Better Than

Hope is a category of transcedence, by means of which a man does not permit what he senses and experiences to be the sole criterion of what is possible. It is the belief or the conviction that present reality (what I see) does not exhaust the potentialities of the given data. Hope opens the present to the future; it enables a man to look ahead, to break the fixity of what he observes, and to perceive the world as open-textured. The categories of possibility and of transcendence interweave a closely stitched fabric - hope says that tomorrow can be better than today.

scholarly journals Evaluation of passive autocatalytic recombiners operation efficiency by means of the lumped parameter approach

Nukleonika ◽  
2015 ◽  
Vol 60 (2) ◽  
pp. 339-345 ◽  
Author(s):  
Tomasz Bury
Keyword(s):  
Hydrogen Generation ◽  
Cooling System ◽  
Component Mixture ◽  
Pressurized Water ◽  
Water Reactor ◽  
Safety Issues ◽  
Loss Of Coolant Accident ◽  
Lumped Parameter ◽  
Core Cooling ◽  
Parameter Approach

Abstract The problem of hydrogen behavior in containment buildings of nuclear reactors belongs to thermal-hydraulic area. Taking into account the size of systems under consideration and, first of all, safety issues, such type of analyses cannot be done by means of full-scale experiments. Therefore, mathematical modeling and numerical simulations are widely used for these purposes. A lumped parameter approach based code HEPCAL has been elaborated in the Institute of Thermal Technology of the Silesian University of Technology for simulations of pressurized water reactor containment transient response. The VVER-440/213 and European pressurised water reactor (EPR) reactors containments are the subjects of analysis within the framework of this paper. Simulations have been realized for the loss-of-coolant accident scenarios with emergency core cooling system failure. These scenarios include core overheating and hydrogen generation. Passive autocatalytic recombiners installed for removal of hydrogen has been taken into account. The operational efficiency of the hydrogen removal system has been evaluated by comparing with an actual hydrogen concentration and flammability limit. This limit has been determined for the three-component mixture of air, steam and hydrogen. Some problems related to the lumped parameter approach application have been also identified.

The Influence of Variable-Speed Waveforms on Vibration Suppression in Time-Varying Speed Cutting

2013 ◽  
Vol 690-693 ◽  
pp. 2514-2518
Author(s):  
Juan Cong ◽  
Yun Wang ◽  
Wei Na Yu
Keyword(s):  
Wave Speed ◽  
Vibration Suppression ◽  
Sine Wave ◽  
Time Varying ◽  
Variable Speed ◽  
Suppression Effect ◽  
Speed Variation ◽  
Input And Output ◽  
System Input ◽  
Better Than

Through the research on the change of system input and output energy in time-varying speed cutting, the influence of variable-speed waveforms on vibration suppression effect in time-varying speed cutting is quantitatively analyzed in this paper. A conclusion can be drawn that sine wave speed variation is better than triangle wave speed variation in vibration suppression.

The role of third windows on human sound transmission of forward and reverse stimulations: A lumped-parameter approach

2020 ◽  
Vol 147 (3) ◽  
pp. 1478-1490 ◽  
Author(s):  
Lin Xue ◽  
Houguang Liu ◽  
Wenbo Wang ◽  
Jianhua Yang ◽  
Yu Zhao ◽  
...  
Keyword(s):  
Sound Transmission ◽  
Lumped Parameter ◽  
Parameter Approach

Stirling Thermocompressor: Lumped Parameter Modeling and Experimental Impact of Displacer Motion Profile on Work Output

2019 ◽  
Author(s):  
Seth Thomas ◽  
Eric J. Barth
Keyword(s):  
Experimental Validation ◽  
Model Parameters ◽  
Work Output ◽  
System Dynamics Model ◽  
Dynamics Model ◽  
Lumped Parameter ◽  
Stirling Engines ◽  
Simplified Modeling ◽  
Parameter Approach ◽  
Motion Profile

Abstract The thermocompressor, a little-known class of Stirling devices that efficiently compresses gas, presents new challenges for modeling and experimental validation. In modeling, traditional analytic assumptions about displacer motion are limiting. In experimental verification, few devices have actually been built and tested. In this paper, the authors test the feasibility of a lumped-parameter approach for predicting the performance of Stirling thermocompressors subject to different displacer motion profiles. Since the displacer of a thermocompressor can be controlled independently, unlike kinematic Stirling engines or dynamic Stirling engines, and has a large influence on output power and efficiency of the device, it is crucial that this is well captured by a system dynamics model for control. Key model parameters are simulated and results are experimentally verified on one of the few, if only, experimental thermocompressor platforms in the world. Conclusions are drawn regarding simplified modeling of the regenerator’s effectiveness and the effects on device work output by varying the displacer piston’s motion profile using different waveforms.

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