Modelling and Performance of an Experimental Active Vibration Isolator

1995 ◽  
Vol 117 (3A) ◽  
pp. 272-278 ◽  
Author(s):  
L. R. Miller ◽  
M. Ahmadian ◽  
C. M. Nobles ◽  
D. A. Swanson
Keyword(s):  
Transfer Functions ◽  
Dynamic Stiffness ◽  
Graph Model ◽  
Electromagnetic Actuator ◽  
Vibration Isolator ◽  
Bond Graphs ◽  
Inertia Effects ◽  
Active Vibration ◽  
And Performance ◽  
Insight Into

The performance of an active vibration isolator consisting of a fluid mount and an electromagnetic actuator is discussed. The electromagnetic actuator augments the inertia effects of the fluid mount to reduce the dynamic stiffness of the mount at the vibrational disturbance frequencies of the engine. The active isolator is modeled using bond graphs. Dynamic stiffness, blocked force, and free displacement transfer functions are developed from the bond graph model to gain insight into the active mount’s performance. A mount effectiveness analysis shows that reducing the mount’s dynamic stiffness results in better dynamic isolation. Numerical simulations along with laboratory testing of the active isolator are used to evaluate the performance of the mount. A simple laboratory experiment shows that an active mount can be controlled to have a dynamic stiffness that is 100 times (40 dB) lower than a passive mount, without sacrificing static stiffness.

Design and experimental validation of a vibration isolator with high-static low-dynamic stiffness and operating point variable property

2021 ◽  
pp. 107754632199052
Author(s):  
Zhenhua Zhou ◽  
Minrui Zhou ◽  
Zhihui Dai ◽  
Xin Liu ◽  
Zhanhui Li
Keyword(s):  
Experimental Validation ◽  
Dynamic Stiffness ◽  
Negative Stiffness ◽  
Vibration Isolator ◽  
Coil Spring ◽  
Variable Property ◽  
Leaf Springs ◽  
Stiffness Characteristic ◽  
Vibration Transmissibility ◽  
And Performance

Vibration isolator with high-static low-dynamic stiffness property has been researched extensively, but the isolator’s stability and performance will be deteriorated with the operation point variation. In this article, a vibration isolator that operation point can be variable was proposed, and it was constructed by combining a coil spring and flexible leaf springs with a negative stiffness magnet spring in parallel. Unlike previous studies, this article focuses on the realization of the high-static low-dynamic stiffness characteristic of the isolator, and the operation point of the vibration isolator can be varied in a certain range. The effects of configuration parameters on the negative stiffness are investigated in detail. Furthermore, the designing procedure to realize the linear negative stiffness with the expected magnitude and range was also developed. A prototype was installed and the vibration transmissibility of the system at different operation points was measured, the experimental results indicated that the isolator can be kept stable in different operation points, and the performance does not deteriorate with the variation of the operation point. The effectiveness of the designing procedure of the realization of linear negative stiffness with the expected magnitude and range and the variable of the operation point of the isolator was validated.

An insight into the effect of calcination conditions on catalytic cracking of toluene over 3Fe8Ni/palygorskite: Catalysts characterization and performance

Fuel ◽  
2017 ◽  
Vol 190 ◽  
pp. 47-57 ◽  
Author(s):  
Xuehua Zou ◽  
Tianhu Chen ◽  
Haibo Liu ◽  
Ping Zhang ◽  
Zhiyuan Ma ◽  
...  
Keyword(s):  
Catalytic Cracking ◽  
And Performance ◽  
Insight Into

A novel active vibration isolator applied for micro-gyro by array of deposited electrodes

2009 ◽  
Vol 15 (7) ◽  
pp. 1017-1026
Author(s):  
Nan-Chyuan Tsai ◽  
Chung-Yang Sue ◽  
Bing-Hong Liou
Keyword(s):  
Vibration Isolator ◽  
Active Vibration

An Increase in Accuracy of Robotic Milling

2017 ◽  
Vol 865 ◽  
pp. 450-456 ◽  
Author(s):  
Yu.V. Ilyukhin ◽  
Ruslan Kolesnichenko
Keyword(s):  
Computer Simulation ◽  
Impedance Control ◽  
Dynamic Stiffness ◽  
Milling Process ◽  
Motor Drives ◽  
Theoretical Research ◽  
Robotic Milling ◽  
Servo Drives ◽  
And Performance ◽  
Increase In Accuracy

The results of the theoretical research and the computer simulation, aimed at increase in accuracy of robotic milling, are presented in the article. An analysis of the mathematical models of the system «technological robot – milling process» is conducted. The prospects of the usage of precision geared dual motor servo drives and trajectory-impedance control systems are underlined. A computer research of the tool movement accuracy during the robotic cylindrical up-milling process, depending on path velocity of the milling cutter and rated value of the cutting depth, has been carried out. Two types of manipulators have been considered: a manipulator with traditional geared servo drives with one motor and a manipulator with the suggested precision dual motor drives. In order to measure accuracy of movements during the computer simulation process a deviation of the tool, normal to the desired trajectory of its movement, has been defined. The results testify the facts that dual motor servo drives allow us to significantly increase dynamic stiffness of technological robots and they promote increasing accuracy and performance of robotic milling.

Design of a Miniaturized Pneumatic Vibration Isolator With High-Static-Low-Dynamic Stiffness

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Yuhu Shan ◽  
Wenjiang Wu ◽  
Xuedong Chen
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Structure Design ◽  
Negative Stiffness ◽  
Vibration Isolator ◽  
Load Bearing Capacity ◽  
Compact Structure ◽  
Chamber Volume ◽  
Isolation Systems ◽  
Magnetic Rings

In the ultraprecision vibration isolation systems, it is desirable for the isolator to have a larger load bearing capacity and a broader isolation bandwidth simultaneously. Generally, pneumatic spring can bear large load and achieve relatively low natural frequency by enlarging its chamber volume. However, the oversized isolator is inconvenient to use and might cause instability. To reduce the size, a miniaturized pneumatic vibration isolator (MPVI) with high-static-low-dynamic stiffness (HSLDS) is developed in this paper. The volume of proposed isolator is minimized by a compact structure design that combines two magnetic rings in parallel with the pneumatic spring. The two magnetic rings are arranged in the repulsive configuration and can be mounted into the chamber to provide the negative stiffness. Then dynamic model of the developed MPVI is built and the isolation performances are analyzed. Finally, experiments on the isolator with and without the magnetic rings are conducted. The final experimental results are consistent with the dynamical model and verify the effectiveness of the developed vibration isolator.

Bond Graph Sign Conventions

1975 ◽  
Vol 97 (2) ◽  
pp. 184-188 ◽  
Author(s):  
A. S. Perelson
Keyword(s):  
Graph Model ◽  
Bond Graph ◽  
Equivalence Classes ◽  
Parameter System ◽  
Bond Graphs ◽  
Lumped Parameter ◽  
Oriented Object

The lack of arbitrariness in the choice of bond graph sign conventions is established. It is shown that an unoriented bond graph may have no unique meaning and that with certain choices of orientation a bond graph may not correspond to any lumped parameter system constructed from the same set of elements. Network interpretations of these two facts are given. Defining a bond graph as an oriented object leads to the consideration of equivalence classes of oriented bond graphs which represent the same system. It is also shown that only changes in the orientation of bonds connecting 0-junctions and 1-junctions can lead to changes in the observable properties of a bond graph model.

scholarly journals Elucidation and refinement of synthetic receptor mechanisms

2020 ◽  
Author(s):  
Hailey I. Edelstein ◽  
Patrick S. Donahue ◽  
Joseph J. Muldoon ◽  
Anthony K. Kang ◽  
Taylor B. Dolberg ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Functional Performance ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Performance Characteristics ◽  
Therapeutic Gene ◽  
High Performing ◽  
Synthetic Receptor ◽  
And Performance ◽  
Insight Into

ABSTRACTSynthetic receptors are powerful tools for engineering mammalian cell-based devices. These biosensors enable cell-based therapies to perform complex tasks such as regulating therapeutic gene expression in response to sensing physiological cues. Although multiple synthetic receptor systems now exist, many aspects of receptor performance are poorly understood. In general, it would be useful to understand how receptor design choices influence performance characteristics. In this study, we examined the modular extracellular sensor architecture (MESA) and systematically evaluated previously unexamined design choices, yielding substantially improved receptors. A key finding that might extend to other receptor systems is that the choice of transmembrane domain (TMD) is important for generating high-performing receptors. To provide mechanistic insights, we adopted and employed a Förster resonance energy transfer (FRET)-based assay to elucidate how TMDs affect receptor complex formation and connected these observations to functional performance. To build further insight into these phenomena, we developed a library of new MESA receptors that sense an expanded set of ligands. Based upon these explorations, we conclude that TMDs affect signaling primarily by modulating intracellular domain geometry. Finally, to guide the design of future receptors, we propose general principles for linking design choices to biophysical mechanisms and performance characteristics.

On the Effects of Mistuning a Force-Excited System Containing a Quasi-Zero-Stiffness Vibration Isolator

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Ali Abolfathi ◽  
M. J. Brennan ◽  
T. P. Waters ◽  
B. Tang
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Vibration Isolators ◽  
Zero Dynamic ◽  
Low Frequency Vibration ◽  
Excited System ◽  
Better Than

Nonlinear isolators with high-static-low-dynamic-stiffness have received considerable attention in the recent literature due to their performance benefits compared to linear vibration isolators. A quasi-zero-stiffness (QZS) isolator is a particular case of this type of isolator, which has a zero dynamic stiffness at the static equilibrium position. These types of isolators can be used to achieve very low frequency vibration isolation, but a drawback is that they have purely hardening stiffness behavior. If something occurs to destroy the symmetry of the system, for example, by an additional static load being applied to the isolator during operation, or by the incorrect mass being suspended on the isolator, then the isolator behavior will change dramatically. The question is whether this will be detrimental to the performance of the isolator and this is addressed in this paper. The analysis in this paper shows that although the asymmetry will degrade the performance of the isolator compared to the perfectly tuned case, it will still perform better than the corresponding linear isolator provided that the amplitude of excitation is not too large.

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