scholarly journals Experimental Demonstration of Cryogenic Cooler Disturbance Attenuation Using the Non-Linear Passive Isolation System

2013 ◽  
Vol 56 (3) ◽  
pp. 121-128 ◽  
Author(s):  
Hyun-Ung OH ◽  
Kyung-Joo LEE ◽  
Hyang-Hee CHOI
Keyword(s):  
Disturbance Attenuation ◽  
Experimental Demonstration ◽  
Isolation System ◽  
Non Linear ◽  
Passive Isolation ◽  
Cryogenic Cooler

Virtual Skyhook Vibration Isolation System

2001 ◽  
Vol 124 (1) ◽  
pp. 63-67 ◽  
Author(s):  
Steve Griffin ◽  
Joel Gussy ◽  
Steven A. Lane ◽  
Benjamin K. Henderson ◽  
Dino Sciulli
Keyword(s):  
Vibration Isolation ◽  
Experimental Measurements ◽  
Simple Test ◽  
Experimental Demonstration ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Design And Implementation ◽  
At Resonance ◽  
Model Predictions ◽  
Passive Isolation

This work presents and demonstrates a passive isolation system that offers the performance of a skyhook damper, but without the need of an inertial reference. This “virtual skyhook” isolation system can be used to reduce the transmission of base excitations to a structure. An analysis of the concept is presented, and model predictions are compared to experimental measurements for a simple test structure. The results demonstrate that the proposed isolation system significantly attenuates transmissibility at resonance without the penalty of increased transmissibility at higher frequencies, which often limits the performance of passive approaches. Practical issues regarding the design and implementation of the virtual skyhook vibration isolation system are also presented and discussed. To the best of the authors’ knowledge, this is the first experimental demonstration of an entirely passive skyhook damper isolation system.

scholarly journals Experimental demonstration of 1.5Hz passive isolation system for precision optical payloads

2017 ◽  
Author(s):  
Guang-yuan Wang ◽  
Xiang Chen ◽  
Xin Guan ◽  
Dong-jing Cao ◽  
Shao-fan Tang ◽  
...  
Keyword(s):  
Experimental Demonstration ◽  
Isolation System ◽  
Passive Isolation

Experimental demonstration of non-linear model-based in-line control of pH

1992 ◽  
Vol 2 (3) ◽  
pp. 145-153 ◽  
Author(s):  
Suhas K. Mahuli ◽  
R. Russell Rhinehart ◽  
James B. Riggs
Keyword(s):  
Linear Model ◽  
Experimental Demonstration ◽  
Model Based ◽  
Non Linear

scholarly journals Low Cost Frictional Seismic Base-Isolation of Residential New Masonry Buildings in Developing Countries: A Small Masonry House Case Study

2017 ◽  
Vol 11 (1) ◽  
pp. 1026-1035 ◽  
Author(s):  
Ahmad Basshofi Habieb ◽  
Gabriele Milani ◽  
Tavio Tavio ◽  
Federico Milani
Keyword(s):  
Finite Element ◽  
Seismic Vulnerability ◽  
Base Isolation ◽  
Low Cost ◽  
Element Model ◽  
Shaking Table ◽  
Fe Model ◽  
Isolation System ◽  
Finite Element Software ◽  
Non Linear

Introduction:An advanced Finite Element model is presented to examine the performance of a low-cost friction based-isolation system in reducing the seismic vulnerability of low-class rural housings. This study, which is mainly numerical, adopts as benchmark an experimental investigation on a single story masonry system eventually isolated at the base and tested on a shaking table in India.Methods:Four friction isolation interfaces, namely, marble-marble, marble-high-density polyethylene, marble-rubber sheet, and marble-geosynthetic were involved. Those interfaces differ for the friction coefficient, which was experimentally obtained through the aforementioned research. The FE model adopted here is based on a macroscopic approach for masonry, which is assumed as an isotropic material exhibiting damage and softening. The Concrete damage plasticity (CDP) model, that is available in standard package of ABAQUS finite element software, is used to determine the non-linear behavior of the house under non-linear dynamic excitation.Results and Conclusion:The results of FE analyses show that the utilization of friction isolation systems could much decrease the acceleration response at roof level, with a very good agreement with the experimental data. It is also found that systems with marble-marble and marble-geosynthetic interfaces reduce the roof acceleration up to 50% comparing to the system without isolation. Another interesting result is that there was little damage appearing in systems with frictional isolation during numerical simulations. Meanwhile, a severe state of damage was clearly visible for the system without isolation.

A Study of Chaotic Motion on Non-Linear Vibration-Isolation System

2001 ◽  
Author(s):  
Qing Ouyang ◽  
Shi-Jian Zhu ◽  
Yin Shi
Keyword(s):  
Frequency Band ◽  
Chaotic Motion ◽  
Vibration Isolation ◽  
Physical Parameters ◽  
Linear Vibration ◽  
Chaotic State ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Broad Frequency Band ◽  
Non Linear

Abstract This paper deals with the vibration isolation efficiency of non-linear vibration-isolation system in a desired chaotic state. Numerical calculation shows that the response of a non-linear vibration system might have broad frequency band characterization, even though the excitation is a harmonic one if some physical parameters of the system is in certain value regimes, hence the force transferred to the supporting foundation from the isolated body will be a broad frequency band one. The practical experimental set was designed. In order to control the system in a desired chaotic state, the isolator must be a non-linear one with variable stiffness and damping. The chaotic motion of the system was identified through phase space reconstruction and spectral analysis based on the measured test data. The result shows that it is feasible to decrease the single line spectrum component significantly in the response by means of controlling chaotic vibration.

Sliding-Mode Control Algorithm for a Hard-Mounted Isolation System

2007 ◽  
Author(s):  
Yung-Peng Wang ◽  
Jen-Chieh Tsao
Keyword(s):  
Sliding Mode Control ◽  
Control Algorithm ◽  
Sliding Mode ◽  
Isolation System ◽  
Mode Control ◽  
Active Isolation ◽  
Ultra Precision ◽  
Passive Isolation ◽  
Isolation Systems ◽  
Isolation Performance

It is well known that the trend of current technology development is microscopic and ultra-precision, especially in the areas of semiconductor manufacturing, ultra-precision machining, MEMS, microbiology and nanotechnology. Hence, vibration becomes a significant problem in those fields. There are two types of vibration control techniques. One is passive isolation system; the other is active isolation system. Passive isolation system can provide better performance for higher frequencies. Active isolation system is used to improve the isolation performance for lower frequencies. However, passive isolation system has bad performance around the natural frequency. In addition, it cannot eliminate the effects of onboard disturbances. Therefore, active isolation system becomes the major technology in the applications of microvibration control for precision equipment. In practice, all active isolation systems are based upon a hybrid concept, combining a passive isolator for higher frequencies and a servo control system for lower frequencies. This combination allows for two significantly different configurations, which can be categorized as: soft-mounted isolation systems and hard-mounted isolation systems. The soft-mounted systems are inherently insensitive to resonance in the main structure below the isolators. Yet, they are sensitive to resonances in the isolated platform. The hard-mounted systems are extremely stiff and allows for large onboard disturbance forces without excessive motion. However, the major drawback with a hard-mounted system is that vibration isolation performance suffers from the passive-active compromise and is unable to come up to the optimal performance. In this paper, a sliding-mode control algorithm is developed for a hard-mounted isolation system with a piezoactuator. Based on the bounds of environmental vibrations and onboard disturbances, the sliding-mode control algorithm can make the hard-mounted isolation system achieve the optimal and robust performance of low vibration transmissibility and high stiffness. The results are verified by the numerical simulations.

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