local resonance
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2022 ◽  
Vol 186 ◽  
pp. 108450
Author(s):  
Gen Li ◽  
Yan Chen ◽  
Weiting Chen ◽  
Jinming Liu ◽  
Huan He

2021 ◽  
pp. 107754632110598
Author(s):  
Hao Jin ◽  
Hongying Wang ◽  
Zheng Li ◽  
Xin Zhou

With the continuous increase of subway operating mileage, the problem of subway vibration has become more and more significant. Nowadays, the point-supported floating-slab track is recognized as the best method to control track vibration, which is mainly designed based on the mass-spring-damping theory. How to further improve the vibration control ability of the point-supported floating-slab track? In this paper, a new type of rubber point-supported floating slab track is designed based on the local resonance theory. Through calculation and dynamic test, it is obtained as follows: (1) The band gap of the point support structure by local resonance type depends on the two vertical vibration modes. (2) As the elastic modulus of the cladding layer increases, the bandwidth of the band gap of the corresponding structure increases significantly. (3) The increase of the vibrator density can increase the bandwidth, while reducing the start and stop frequencies, which is beneficial to attenuate the resonance of the floating-slab track. (4) The cushion material parameters of point support structure by local resonance type 2 will not affect the band gap. The increase in sleeve density will reduce the band gap, which is not conducive to vibration reduction. Local resonance type floating-slab track will be the development direction of track vibration-reduction measures in the future.


2021 ◽  
Vol 184 ◽  
pp. 108353
Author(s):  
Muhammad ◽  
Sayed Iftikhar Hussain ◽  
C.W. Lim
Keyword(s):  

2021 ◽  
Vol 140 (5) ◽  
pp. 455-462
Author(s):  
Han Zhang ◽  
Pengxiang Hao ◽  
Yang Gao ◽  
Yong Cheng ◽  
Guangzeng Li ◽  
...  

Author(s):  
Marea Mitchell

While mermaids have been found all around the world, their literary and cultural representations are traditionally associated with Europe. Recently attention has been paid to the particular resonance of mer-folk narratives in specifically Australian contexts. Hayward, Floyd, Snell, Organ and Callaway have drawn attention to examples of mer-worlds that directly intersect with and comment on Australian environments. Beginning in the late 19th Century, predominantly women writers relocate mermen and mermaids to explore relationships between land and sea, city and bush that have local resonance for young readers. These stories are often accompanied by rich illustrations designed to appeal to young imaginations. This note comments on three writers whose work relates mer-cultures to Australia: J.M Whitfield, Pixie O’Harris and Harriet Stephens, along with their illustrators, G.W Lambert, Ida Rentoul Outhwaite and O’Harris herself.


2021 ◽  
Vol 42 (11) ◽  
pp. 1555-1570
Author(s):  
Chenxu Qiang ◽  
Yuxin Hao ◽  
Wei Zhang ◽  
Jinqiang Li ◽  
Shaowu Yang ◽  
...  

AbstractThe concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural vibration reduction. In this paper, a novel sandwich-like plate model with local resonator to acquire specific low-frequency bandgaps is proposed. The core layer of the present local resonator is composed by the simply supported overhanging beam, linear spring and mass block, and well connected with the upper and lower surface panels. The simply supported overhanging beam is free at right end, and an additional linear spring is added at the left end. The wave equation is established based on the Hamilton principle, and the bending wave bandgap is further obtained. The theoretical results are verified by the COMSOL finite element software. The bandgaps and vibration characteristics of the local resonance sandwich-like plate are studied in detail. The factors which could have effects on the bandgap characteristics, such as the structural damping, mass of vibrator, position of vibrator, bending stiffness of the beam, and the boundary conditions of the sandwich-like plates, are analyzed. The result shows that the stopband is determined by the natural frequency of the resonator, the mass ratio of the resonator, and the surface panel. It shows that the width of bandgap is greatly affected by the damping ratio of the resonator. Finally, it can also be found that the boundary conditions can affect the isolation efficiency.


Author(s):  
Qiang Yi ◽  
Caiyou Zhao ◽  
Ping Wang

To overcome the ill-conditioned matrix problem of the traditional transfer matrix method, the Floquet transform method and supercell technology are used to study the defect states of the periodic track structure. By solving the equations of the supercell directly, the propagation characteristics of elastic waves in the track structure with defects are analyzed. The existence of defects destroys the periodicity of track structure, thus resulting in the formation of defect states within the band gaps. Moreover, the elastic wave is localized near the defect position at the frequency of the defect state. The formation mechanism of the defect state in track structure can be explained by the local resonance at the defect. With the expansion of the defect range, the number of local resonance modes that can be formed near the defect increases, thus generating multiple defect states. Furthermore, the defect state enhances the vibration of the structure adjacent to the defect. Therefore, the vibration transmission coefficient in a finite-length range can be used to detect the defect characteristics in the track structure, and the defect degree can be evaluated by the peak frequency of the vibration transmission coefficient within the band gap.


2021 ◽  
Vol 165 ◽  
pp. 107969
Author(s):  
Minghui Zhang ◽  
Chao Hu ◽  
Chengzhen Yin ◽  
Qing-Hua Qin ◽  
Jianshan Wang

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