Ultra-low frequency vertical vibration isolator based on LaCoste spring linkage

2014 ◽  
Vol 85 (10) ◽  
pp. 104502 ◽  
Author(s):  
G. Li ◽  
H. Hu ◽  
K. Wu ◽  
G. Wang ◽  
L. J. Wang
Keyword(s):  
Low Frequency ◽  
Vertical Vibration ◽  
Vibration Isolator

An active ultra-low frequency vertical vibration isolator

2016 ◽  
Author(s):  
G. Wang ◽  
H. Hu ◽  
K. Wu ◽  
G. Li ◽  
L. J. Wang
Keyword(s):  
Low Frequency ◽  
Vertical Vibration ◽  
Vibration Isolator

Novel Euler-LaCoste linkage as a very low frequency vertical vibration isolator

2012 ◽  
Vol 83 (8) ◽  
pp. 085108 ◽  
Author(s):  
M. A. Hosain ◽  
A. Sirr ◽  
L. Ju ◽  
D. G. Blair
Keyword(s):  
Low Frequency ◽  
Vertical Vibration ◽  
Vibration Isolator ◽  
Very Low Frequency

scholarly journals Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure

2016 ◽  
Vol 65 (20) ◽  
pp. 200702
Author(s):  
Wang Guan ◽  
Hu Hua ◽  
Wu Kang ◽  
Li Gang ◽  
Wang Li-Jun
Keyword(s):  
Low Frequency ◽  
Vertical Vibration ◽  
Vibration Isolator ◽  
Beam Structure ◽  
Two Stage

An Ultra-Low Frequency Active Vertical Vibration Isolator With Geometric Anti-Spring Structure

2017 ◽  
Author(s):  
Jiamin Yao ◽  
Kang Wu ◽  
Jin Qian ◽  
Guan Wang ◽  
Meiying Guo ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Low Frequency ◽  
Ground Vibration ◽  
Stage Structure ◽  
Target Object ◽  
Vertical Vibration ◽  
Vibration Isolator ◽  
Restoring Force ◽  
Second Stage ◽  
Allowable Load

Vibration isolators have been widely used to keep the target object from the ground vibration in order to improve the measurement accuracy. Nowadays, the ultra-low frequency vibration isolator based on a two-stage structure shows the best performance. Traditionally, vertically suspended springs are usually applied as the second-stage. As the requirement of the low stiffness, the springs need to be long, which brings the disadvantages of relatively large size and small allowable load. A novel ultra-low frequency active vertical vibration isolator is proposed in this paper, which applies geometric anti-spring (GAS) instead of the second-stage suspended springs. The isolated object (the second stage) is supported by GAS fixed on an inner frame (the first stage), and the inner frame is hung with supporting springs from the base of the vibration isolator. The inner frame is driven by a voice coil to track the motion of the isolated object according to the relative motion signal detected by a photoelectric detector. Ideally, GAS provides zero restoring force for the object, thus realizing a long natural resonance period. Experimental results show that the isolator can achieve a resonance period of 14.7 s, compared with a simulated result of 20.7 s. Therefore, it is accessible to reduce the isolator’s volume and increase the allowable load by replacing the traditional second-stage suspended springs with GAS, without harming the vibration isolation effect. Promisingly it will be applied in free-falling and atomic-interference absolute gravimeters, and other precise measurements.

scholarly journals Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3015 ◽  
Author(s):  
Jijian Lian ◽  
Hongzhen Wang ◽  
Haijun Wang
Keyword(s):  
Low Frequency ◽  
Field Tests ◽  
Vertical Vibration ◽  
Transmission Mechanism ◽  
Structural Vibration ◽  
Hydropower Station ◽  
Fe Model ◽  
Vibration Transmission ◽  
Underground Powerhouse ◽  
Mechanical Models

Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.

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