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Symmetry
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The Study of Low Frequency Vibration and Noise Reduction
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The Study of Low Frequency Vibration and Noise Reduction

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 8406

Special Issue Editor

Dr. Nansha Gao

E-Mail Website
Guest Editor
School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China
Interests: noise and vibration reduction; acoustic metamaterial; underwater absorption/insulation; composite porous metastructure
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Vibration and noise control is a very practical research field for a long time. In the past decade, many control methods and new materials and structures have emerged to solve the problem of low-frequency vibration and noise. For example, acoustic black holes are used to control bending waves in thin plates, acoustic metamaterials are used to achieve low-frequency broadband sound absorption and low-frequency high sound insulation, and elastic metasurfaces are used to control elastic wave transmission. The continuous exploration in this field not only enriches the basic theory of vibration and noise but also plays a huge application potential in related products in industry. This Special Issue welcomes researchers to contribute to the field of vibration and noise control, including control methods, structures, materials, and the discovery of new physical mechanisms. Vibration and noise control is a very practical research field. Because the length of low-frequency acoustic wave and elastic wave are too large for the structure size, the control of low-frequency internal vibration and noise has been a very challenging and hot research topic. Natural materials and some classical structures have been unable to meet the increasing comfort requirements. In the past decade, many control methods and new materials and structures have been developed to solve the problem of low-frequency vibration and noise. For example, acoustic black holes are used to control bending waves in thin plates, acoustic metamaterials are used to achieve low-frequency broadband sound absorption and low-frequency high sound insulation, and elastic metasurfaces are used to control elastic wave transmission. The continuous exploration in this field not only enriches the basic theory of vibration and noise but also promotes the development of physics, materials science, and other disciplines, and also has significant application potential in related industrial products. This Special Issue welcomes contributions from researchers in the field of vibration and noise control, including vibration and noise control methods, new structures, new materials, new physical mechanisms, and new experimental methods.

Dr. Nansha Gao
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • metamaterials
  • vibration and noise reduction
  • acoustic black hole
  • fluctuation control
  • control methods

Published Papers (4 papers)

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Research

23 pages, 13398 KiB  
Article
Analysis of Sound Absorption Characteristics of Acoustic Ducts with Periodic Additional Multi-Local Resonant Cavities
by Junyi Liu, Ting Wang and Meixia Chen
Symmetry 2021, 13(12), 2233; https://doi.org/10.3390/sym13122233 - 23 Nov 2021
Cited by 3 | Viewed by 1799
Abstract
With the aim of applying various Helmholtz resonant cavities to achieve low-frequency sound absorption structures, a pipe structure with periodic, additional, symmetrical, multi-local resonant cavities is proposed. A thin plate with additional mass is placed in the cylindrical Helmholtz resonant cavity structure to [...] Read more.
With the aim of applying various Helmholtz resonant cavities to achieve low-frequency sound absorption structures, a pipe structure with periodic, additional, symmetrical, multi-local resonant cavities is proposed. A thin plate with additional mass is placed in the cylindrical Helmholtz resonant cavity structure to form a symmetric resonant cavity structure and achieve multi-local resonance. The simulation results show that the periodic structure proposed in this paper can produce multiple, high acoustic transmission loss peaks and multiple lower broadband sound absorption frequency bands in the low-frequency range. In this paper, this idea is also extended to the Helmholtz resonant cavity embedded with multiple additional mass plates. The results show that the periodic arrangement of the multi-local resonant symmetric cavity inserted into multiple plates with mass can significantly increase its transmission loss and show a better performance on low-frequency sound absorption characteristics. Full article
(This article belongs to the Special Issue The Study of Low Frequency Vibration and Noise Reduction)
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16 pages, 2015 KiB  
Article
Analysis of Free Vibration Characteristics of Cylindrical Shells with Finite Submerged Depth Based on Energy Variational Principle
by Rui Nie, Tianyun Li, Xiang Zhu and Cheng Zhang
Symmetry 2021, 13(11), 2162; https://doi.org/10.3390/sym13112162 - 11 Nov 2021
Cited by 1 | Viewed by 1630
Abstract
Based on the principle of energy variation, a calculation model for the free vibration characteristics of a cylindrical shell with a finite submerged depth considering the influence of the free liquid surface is established in this paper. First, the Euler beam function is [...] Read more.
Based on the principle of energy variation, a calculation model for the free vibration characteristics of a cylindrical shell with a finite submerged depth considering the influence of the free liquid surface is established in this paper. First, the Euler beam function is used instead of the shell axial displacement function to obtain the shell kinetic energy and potential energy. Then, by using the mirror image method, the analytical expression of the fluid velocity potential considering the free surface is obtained, and the flow field is added to the system energy functional in the form of fluid work. Then the energy functional is changed to obtain the shell–liquid coupled vibration equation. Solving the equation can obtain the natural frequencies and modes of the structure. The comparison with the finite element calculation results verifies the accuracy of the calculation model in this paper. The research on the influence of the free liquid surface shows that compared to the infinite domain, the free liquid surface destroys the symmetry of the entire system, resulting in a difference in the natural frequency of the positive and negative modes of the shell, and the circumferential mode shapes are no longer mutually uncoupled trigonometric functions. The existence of free liquid surface will also increase the natural frequency of the same order mode, and the closer to the free surface, the natural frequency is greater. As the immersion depth increases, the free vibration characteristics will quickly tend to the result of infinite domain. Additionally, when the immersion depth is equal to or greater than four times the radius of the shell structure, it can be considered that the free liquid surface has no effect. These law and phenomena have also been explained from the mechanism. The method in this paper provides a new analytical solution pattern for solving this type of problem. Full article
(This article belongs to the Special Issue The Study of Low Frequency Vibration and Noise Reduction)
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12 pages, 2932 KiB  
Article
Study on Low-Frequency Band Gap Characteristics of a New Helmholtz Type Phononic Crystal
by Dong-Hai Han, Jing-Bo Zhao, Guang-Jun Zhang and Hong Yao
Symmetry 2021, 13(8), 1379; https://doi.org/10.3390/sym13081379 - 29 Jul 2021
Cited by 10 | Viewed by 1657
Abstract
In order to solve the problem of low-frequency noise of aircraft cabins, this paper presents a new Helmholtz type phononic crystal with a two-dimensional symmetric structure. Under the condition of the lattice constant of 62 mm, the lower limit of the first band [...] Read more.
In order to solve the problem of low-frequency noise of aircraft cabins, this paper presents a new Helmholtz type phononic crystal with a two-dimensional symmetric structure. Under the condition of the lattice constant of 62 mm, the lower limit of the first band gap is about 12 Hz, and the width is more than 10 Hz, thus the symmetric structure has distinct sound insulation ability in the low-frequency range. Firstly, the cause of the low-frequency band gap is analyzed by using the sound pressure field, and the range of band gaps is calculated by using the finite element method and the spring-oscillator model. Although the research shows that the finite element calculation results are basically consistent with the theoretical calculation, there are still some errors, and the reasons for the errors are analyzed. Secondly, the finite element method and equivalent model method are used to explore the influence of parameters of the symmetric structure on the first band gap. The result shows that the upper limit of the first band gap decreases with the increase of the lattice constant and the wedge height and increases with the increase of the length of wedge base; the lower limit of the band gap decreases with the increase of the wedge height and length of wedge base and is independent of the change of lattice constant, which further reveals the essence of the band gap formation and verifies the accuracy of the equivalent model. This study provides some theoretical support for low-frequency noise control and broadens the design idea of symmetric phononic crystal. Full article
(This article belongs to the Special Issue The Study of Low Frequency Vibration and Noise Reduction)
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15 pages, 2948 KiB  
Article
Stability Design of Air Vibration Isolation Device for a High Power Density Main Engine
by Jingmin Zhao, Wenjun Bu, Liang Shi and Zechao Hu
Symmetry 2021, 13(7), 1244; https://doi.org/10.3390/sym13071244 - 10 Jul 2021
Cited by 1 | Viewed by 1605
Abstract
In order to improve the alignment stability of the air vibration isolation device of a high-powered main engine, we established a mechanical model for the air vibration isolation system and analyzed the alignment deviation of the device and the vibration decoupling conditions of [...] Read more.
In order to improve the alignment stability of the air vibration isolation device of a high-powered main engine, we established a mechanical model for the air vibration isolation system and analyzed the alignment deviation of the device and the vibration decoupling conditions of the system. Additionally, an optimized design method for the dual-direction support of the air vibration isolators positioned symmetrically on the main engine was proposed. The resultant design showed that when compared to the conventional inclined support of air springs for the main engines onboard ships, the dual-direction support design proposed in this paper for air vibration isolation could eliminate the adverse effect of the output torque reaction on the alignment of the main engine and decouple the system to reduce the number of peaks in the frequency response of vertical force transmission. The optimized design could effectively improve the alignment performance of the device for tilted or swinging operating conditions and maintain the good alignment stability of the device when a single vertical support air spring fails. A single vertical support air spring failure mainly affects the stability of the main engine under the reaction of the output torque, especially the air springs arranged in the corner, while the air springs arranged in the middle have no effect. The optimized design could also improve the vibration isolation performance. This is important for the design of air spring vibration isolation devices for high power density main engines. Full article
(This article belongs to the Special Issue The Study of Low Frequency Vibration and Noise Reduction)
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