Editorial

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4 pages, 142 KiB

Open AccessEditorial

State-of-the-Art on Vibro-Acoustics of Structures

by Tai Yan Kam

Appl. Sci. 2020, 10(8), 2867; https://0-doi-org.brum.beds.ac.uk/10.3390/app10082867 - 21 Apr 2020

Cited by 2 | Viewed by 1546

Abstract

Structures when subjected to time varying loads will vibrate and generate acoustic waves [...] Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

Research

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12 pages, 4596 KiB

Open AccessArticle

Parallel Load-Bearing and Damping System Design and Test for Satellite Vibration Suppression

by Shenyan Chen, Zihan Yang, Minxiao Ying, Yanwu Zheng, Yanjie Liu and Zhongwen Pan

Appl. Sci. 2020, 10(4), 1548; https://0-doi-org.brum.beds.ac.uk/10.3390/app10041548 - 24 Feb 2020

Cited by 7 | Viewed by 2800

Abstract

The traditional series-type satellite vibration suppression scheme significantly decreases satellite frequency, which leads to difficulty in controlling the amplitude. In the present work, a new parallel viscous damping scheme is adopted on the Payload Adaptor Fitting (PAF), which aims to integrate a load-bearing [...] Read more.

The traditional series-type satellite vibration suppression scheme significantly decreases satellite frequency, which leads to difficulty in controlling the amplitude. In the present work, a new parallel viscous damping scheme is adopted on the Payload Adaptor Fitting (PAF), which aims to integrate a load-bearing design and vibration reduction. The vibration amplitude and weight are the most important design requirements of the damping system. The Finite Element (FE) model of PAF was established. Through a series of analyses, the appropriate number and coefficient of dampers were determined. The damping force was calculated according to the damping coefficient and the relative velocity between the two ends of the damper. Based on the damping force and the installation dimensions, the damping rod was designed. The force–velocity test was carried out on the damping rod prototype, which showed its performance satisfies the requirements. With the topology optimization and sizing optimization technology, the light-weight supports were designed and manufactured. One damping rod and two supports were assembled as one set of dampers. Eight sets of dampers were installed on the PAF. Vibration tests were conducted on the damping state PAF. The results showed that the proposed system is effective at suppressing vibration and maintaining stiffness simultaneously. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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16 pages, 1979 KiB

Open AccessArticle

Robust Adaptive Control for an Aircraft Landing Gear Equipped with a Magnetorheological Damper

by Quoc Viet Luong, Dae-Sung Jang and Jai-Hyuk Hwang

Appl. Sci. 2020, 10(4), 1459; https://0-doi-org.brum.beds.ac.uk/10.3390/app10041459 - 21 Feb 2020

Cited by 26 | Viewed by 4806

Abstract

A landing gear of an aircraft is required to function at touchdown in different landing scenarios with parametric uncertainties. A typical passive damper in a landing gear has limited performance in differing landing scenarios, which can be overcome with magnetorheological (MR) dampers. An [...] Read more.

A landing gear of an aircraft is required to function at touchdown in different landing scenarios with parametric uncertainties. A typical passive damper in a landing gear has limited performance in differing landing scenarios, which can be overcome with magnetorheological (MR) dampers. An MR damper is a semi-active system that can adjust damping force by changing the amount of electric current applied to it. This paper proposes a new robust controller based on model reference sliding mode control and adaptive hybrid control to improve the efficiency of absorbing landing impact energy, not only considering the variables of aircraft weight and sink speed but also managing uncertainties, such as ambient temperature and passive damping coefficient. To verify the effectiveness of the proposed controller, comparative numerical simulations were performed with a passive damper, a skyhook controller, and the proposed controller under various landing scenarios. The simulation results show that the proposed controller improves the total energy absorber efficiency by up to 10% higher than that of the skyhook controller. In addition, the proposed controller is demonstrated to have better adaptability and robustness than the other control algorithms in the differing landing scenarios and parametric uncertainties. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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21 pages, 5356 KiB

Open AccessArticle

Effects of Acoustic Black Hole Parameters and Damping Layer on Sound Insulation Performance of ABH Circular Plate

by Xiaofei Du, Dacheng Huang, Qidi Fu and Jianrun Zhang

Appl. Sci. 2019, 9(24), 5366; https://0-doi-org.brum.beds.ac.uk/10.3390/app9245366 - 09 Dec 2019

Cited by 18 | Viewed by 3492

Abstract

The acoustic black hole (ABH) can be utilized to achieve aggregation of flexural wave in structures with the feature that the thickness gradually reduced to zero with a power exponent no less than 2. The above characteristics could be applied in vibration reduction, [...] Read more.

The acoustic black hole (ABH) can be utilized to achieve aggregation of flexural wave in structures with the feature that the thickness gradually reduced to zero with a power exponent no less than 2. The above characteristics could be applied in vibration reduction, noise attenuation or improving sound insulation. Previous literatures on vibration and acoustic characteristics of ABH structures mainly focus on the structural response under mechanical force excitation, while the transmission loss (TL) of circular plates embedded with two-dimensional ABHs investigated in this paper is a vibro-acoustic coupling procedure under excitation of diffuse sound field. Series of vibro-acoustic coupling finite element models (FEM) for TL analysis of ABH circular plates were established by automatic matched layer (AML) method in this paper and an experimental platform for measuring TLs of ABH circular plates and uniform plates was constructed. The accuracy of the FEM analysis was verified by experimental measurements. To systematically analyze the influence mechanism of parameters of the ABH on TLs of ABH circular plates, the effects of diameter, orientation, number, and truncation thickness of ABHs on TLs of ABH circular plates were further studied. The effect of the damping layer on TLs of circular plates embedded with 1 and 19 ABHs was also analyzed and it reveals that the influence of damping layer mainly concentrates on the first-order resonance frequency and damping-controlled region of the plate, and at some frequencies, the greater the damping layer thickness, the worse the sound insulation performance, despite that the modal damping loss factor has been increased in the whole frequency domain. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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14 pages, 14099 KiB

Open AccessArticle

Vibro-Acoustic Numerical Simulation for Analyzing Floor Noise of a Multi-Unit Residential Structure

by Sangki Park

Appl. Sci. 2019, 9(20), 4289; https://0-doi-org.brum.beds.ac.uk/10.3390/app9204289 - 12 Oct 2019

Cited by 1 | Viewed by 4093

Abstract

In South Korea, the construction of new multi-unit residential structures has been continuously increasing in order to accommodate multiple households in single structures. However, the presence of walls and floors shared with neighbors makes these structures exceptionally vulnerable to floor noise transmission when [...] Read more.

In South Korea, the construction of new multi-unit residential structures has been continuously increasing in order to accommodate multiple households in single structures. However, the presence of walls and floors shared with neighbors makes these structures exceptionally vulnerable to floor noise transmission when the noise of everyday life occurs. In particular, South Korea has many social problems associated with such floor noise, which require the utmost attention and immediate resolution. In this study, a 17-story structure was selected as a test structure. Field measurements were carried out. A numerical model for the 17-story structure was developed in order to perform a vibro-acoustic analysis. The validation of the numerical model comparing with the field measurement data results shows a good agreement. Finally, it is concluded that numerical analysis can be applied to resolve floor noise problems arising in multi-unit residential structures. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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25 pages, 4342 KiB

Open AccessArticle

Vibro-Acoustic Performance of a Sandwich Plate with Periodically Inserted Resonators

by Zhiwei Guo, Jie Pan and Meiping Sheng

Appl. Sci. 2019, 9(18), 3651; https://0-doi-org.brum.beds.ac.uk/10.3390/app9183651 - 04 Sep 2019

Cited by 12 | Viewed by 2865

Abstract

The vibro-acoustic performance of a sandwich plate with periodic locally resonant (LR) units is examined in this paper, with specific focus on the effect of periodic resonators on the average radiation efficiency and the acoustic radiation to the far field. In order to [...] Read more.

The vibro-acoustic performance of a sandwich plate with periodic locally resonant (LR) units is examined in this paper, with specific focus on the effect of periodic resonators on the average radiation efficiency and the acoustic radiation to the far field. In order to assess the radiation performance, the band-gap properties of an infinite periodic structure and the vibrational response of a finite periodic structure are first studied with closed-form solutions. Subsequently, the acoustic radiation efficiency of the LR sandwich plate is obtained using the concepts of modal radiation. It is shown that the acoustic radiation power can be reduced significantly, not only in the band-gap but also at frequencies close below the band-gap, due to either the decrease in radiation efficiency or the decrease in the vibration response. Thus, the periodic resonators provide a broader attenuation band for the purposes of noise reduction than for vibration reduction. However, for frequencies close above the band-gap, the acoustic performance became worse, owing to the increase in acoustic radiation efficiency. Fortunately, the increased sound radiation above the band-gap can be reduced by adding a small damping to the resonator, which further broadens the attenuation frequency band. The reason for the variation of acoustic radiation efficiency is also studied and can be physically explained by the effective mass of an LR unit, where increased mass corresponds to decreased radiation efficiency and decreased mass corresponds to increased radiation efficiency. Thus, the effective mass can be a useful parameter for designers to estimate which frequency component will be acoustically reduced or acoustically enhanced in a practical design. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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18 pages, 4411 KiB

Open AccessArticle

Vibro-Acoustic Characterization of a Composite Structure Featuring an Innovative Phenolic Foam Core

by Massimo Fortini, Nicola Granzotto and Edoardo Alessio Piana

Appl. Sci. 2019, 9(7), 1276; https://0-doi-org.brum.beds.ac.uk/10.3390/app9071276 - 27 Mar 2019

Cited by 12 | Viewed by 3195

Abstract

Composite panels are being increasingly used in many applications because they can combine several interesting properties, such as high load-bearing capacity, low weight, and excellent thermal insulation. Different core materials can be used for composite sandwich panels, like polystyrene, mineral wool, polyurethane, glass [...] Read more.

Composite panels are being increasingly used in many applications because they can combine several interesting properties, such as high load-bearing capacity, low weight, and excellent thermal insulation. Different core materials can be used for composite sandwich panels, like polystyrene, mineral wool, polyurethane, glass wool, or rigid phenolic foam, which is considered the rigid plastic foam with the best fire-proof properties. During the research and development phase, the use of simulation tools is often required for the improvement of the mechanical behavior of the material. The aim of the paper is to characterize some vibro-acoustic parameters of a sandwich material with phenolic open-cell foam core. The sound transmission loss of the structure is calculated based on its flexural behavior, represented through a frequency-dependent “apparent” bending stiffness which is estimated by natural frequency vibration tests on beam specimens. The comparison between sound transmission loss predictions and measurements in sound transmission suites according to ISO 10140-2 is presented and discussed. Finally, the early-stage prediction potentiality of the mathematical model is investigated when only nominal information is available on the constituent layers, showing that particular attention should be paid to the modifications introduced by the manufacturing process. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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20 pages, 11424 KiB

Open AccessArticle

Experimental and Numerical Investigation of Resonance Characteristics of Novel Pumping Element Driven by Two Piezoelectric Bimorphs

by Yu-Chih Lin, Yu-Hsi Huang and Kwen-Wei Chu

Appl. Sci. 2019, 9(6), 1234; https://0-doi-org.brum.beds.ac.uk/10.3390/app9061234 - 24 Mar 2019

Cited by 6 | Viewed by 2652

Abstract

This paper describes the vibration characteristics of a dual-bimorph piezoelectric pumping element under fluid–structure coupling. Unlike the single bimorph used in most previous studies, the proposed device comprises two piezoelectric bimorphs within an acrylic housing. Amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) was used [...] Read more.

This paper describes the vibration characteristics of a dual-bimorph piezoelectric pumping element under fluid–structure coupling. Unlike the single bimorph used in most previous studies, the proposed device comprises two piezoelectric bimorphs within an acrylic housing. Amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) was used to examine the visible displacement fringes in order to elucidate the anti-phase as well as in-phase motions associated with vibration. Analysis was also conducted using impedance analysis and laser Doppler vibrometer (LDV) based on the measurement of point-wise displacement. The experimental results of resonant frequencies and the corresponding mode shapes are in good agreement with those obtained using finite element analysis. The gain of flow rate obtained by the anti-phase motion of the dual-bimorph pumping element is larger than both those obtained by in-phase motion and the single bimorph pumping element. This work greatly enhances our understanding of the vibration characteristics of piezoelectric pumping elements with two bimorphs, and provides a valuable reference for the further development of bionic pump designs. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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Review

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23 pages, 5959 KiB

Open AccessReview

Advances in Micromanipulation Actuated by Vibration-Induced Acoustic Waves and Streaming Flow

by Zhuo Chen, Xiaoming Liu, Masaru Kojima, Qiang Huang and Tatsuo Arai

Appl. Sci. 2020, 10(4), 1260; https://0-doi-org.brum.beds.ac.uk/10.3390/app10041260 - 13 Feb 2020

Cited by 23 | Viewed by 4583

Abstract

The use of vibration and acoustic characteristics for micromanipulation has been prevalent in recent years. Due to high biocompatibility, non-contact operation, and relatively low cost, the micromanipulation actuated by the vibration-induced acoustic wave and streaming flow has been widely applied in the sorting, [...] Read more.

The use of vibration and acoustic characteristics for micromanipulation has been prevalent in recent years. Due to high biocompatibility, non-contact operation, and relatively low cost, the micromanipulation actuated by the vibration-induced acoustic wave and streaming flow has been widely applied in the sorting, translating, rotating, and trapping of targets at the submicron and micron scales, especially particles and single cells. In this review, to facilitate subsequent research, we summarize the fundamental theories of manipulation driven by vibration-induced acoustic waves and streaming flow. These methods are divided into two types: actuated by the acoustic wave, and actuated by the steaming flow induced by vibrating geometric structures. Recently proposed representative vibroacoustic-driven micromanipulation methods are introduced and compared, and their advantages and disadvantages are summarized. Finally, prospects are presented based on our review of the recent advances and developing trends. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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30 pages, 8863 KiB

Open AccessReview

A Comprehensive Review of Acoustic Methods for Locating Underground Pipelines

by Ying Liu, Daryoush Habibi, Douglas Chai, Xiuming Wang, Hao Chen, Yan Gao and Shuaiyong Li

Appl. Sci. 2020, 10(3), 1031; https://0-doi-org.brum.beds.ac.uk/10.3390/app10031031 - 04 Feb 2020

Cited by 26 | Viewed by 6938

Abstract

Underground pipelines are vital means of transporting fluid resources like water, oil and gas. The process of locating buried pipelines of interest is an essential prerequisite for pipeline maintenance and repair. Acoustic pipe localization methods, as effective trenchless detection techniques, have been implemented [...] Read more.

Underground pipelines are vital means of transporting fluid resources like water, oil and gas. The process of locating buried pipelines of interest is an essential prerequisite for pipeline maintenance and repair. Acoustic pipe localization methods, as effective trenchless detection techniques, have been implemented in locating underground utilities and shown to be very promising in plastic pipeline localization. This paper presents a comprehensive review of current acoustic methods and recent advances in the localization of buried pipelines. Investigations are conducted from multiple perspectives including the wave propagation mechanism in buried pipe systems, the principles behind each method along with advantages and limitations, representative acoustic locators in commercial markets, the condition of buried pipes, as well as selection of preferred methods for locating pipelines based on the applicability of existing localization techniques. In addition, the key features of each method are summarized and suggestions for future work are proposed. Acoustic methods for locating underground pipelines have proven to be useful and effective supplements to existing localization techniques. It has been highlighted that the ability of acoustic methods to locate non-metallic objects should be of particular practical value. While this paper focuses on a specific application associated with pipeline localization, many acoustic methods are feasible across a wide range of underground infrastructures. Full article

(This article belongs to the Special Issue State-of-the-Art on Vibroacoustics and Sound Radiation Control of Structures)

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