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sound absorption coefficient optimization of gradient sintered metal fiber felts

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Science China(Technological Sciences) 2016年第5期59卷 699-708页

作者： MENG Han REN Shu Wei XIN Feng Xian LU Tian Jian MOE Key Laboratory for Multifunctional Materials and Structures Xi'an Jiaotong University State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University

An optimization method for sound absorption of gradient(multi-layered) sintered metal fiber felts is presented. The theoretical model based on dynamic flow resistivity is selected to calculate the sound absorption coefficient of the sintered metal fiber felts since it only requires three key morphological parameters: fiber diameter, porosity and layer thickness. The model predictions agree well with experimental measurements. Objective functions and constraint conditions are then set up to optimize separately the distribution of porosity, fiber diameter, and simultaneous porosity and fiber diameter in the metal fiber. The optimization problem for either a sole frequency or a pre-specified frequency range is solved using a genetic algorithm method. Acoustic performance comparison between optimized and non-optimized metal fibers is presented to confirm the effectiveness of the optimization method. Gradient sintered metal fiber felts hold great potential for noise control applications particularly when stringent restriction is placed on the total volume and/or weight of sound absorbing material allowed to use.

关键词： sound absorption optimization sintered metal fiber felts

sound absorption performance of natural fibers and their composites

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Science China(Technological Sciences) 2012年第8期55卷 2278-2283页

作者： YANG WeiDong LI Yan School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

This research aimed to study the sound absorption properties of natural fibers and their reinforced *** absorption coefficients of three types of natural fibers,i.e.,ramie,flax and jute fibers and their composites were measured by the two-microphone transfer function technique in the impedance *** results were compared with synthetic fibers and their *** was found that both natural fibers and their composites had superior capability of noise *** multi-scale and hollow lumen structures of natural fibers contributed to the high sound absorption ***,the sound absorption properties of these natural fibers were also calculated by the Delany-Bazley and Garai-Pompoli *** showed good agreement with the experimental *** was concluded that multi-functional composite materials can be made by natural fibers so that both the mechanical and acoustical functions can be achieved.

关键词： natural fiber reinforced composites sound absorption impedance tube

Light Electrospun Polyvinylpyrrolidone Blanket for Low Frequencies sound absorption

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Chinese Journal of Polymer Science 2018年第12期36卷 1368-1374页

作者： Joshua Avossa Francesco Brand Francesco Marulo Giuseppe Petrone Stefano Guido Giovanna Tomaiuolo Aniello Costantini Dipartimento di Ingegneria Chimica dei Materiali e della Produzione lndustriale (DICMaPI) Universitgt degli Studi di Napoli Federico II Napoli Italy Dipartimento di lngegneria Industriale (DII) Universita degli Studi di Napoli Federico II Napoli Italy

Light polymeric soundproofing materials （density = 63 kg/m3） of interest for the transportation industry were fabricated through electrospinning. Blankets of electrospun polyvinylpyrrolidone （average fiber diameter = （1.6 ± 0.5） or （2.8 ± 0.5） μm） were obtained by stacking disks of electrospun mats. The sound absorption coefficients were measured using the impedance tube instrument based on ASTM E1050 and ISO 10534-2. For a given set of disks （from a minimum of 6） the sound absorption coefficient changed with the frequency （in the range 200-1600 Hz） following a bell shape curve with a maximum （where the coefficient is greater than 0.9） that shifts to lower frequencies at higher piled disks number and greater fiber diameter. This work showed that electrospinning produced sound absorbers with reduced thickness （2-3 cm） and excellent sound-absorption properties in the low and medium frequency range.

关键词： Electrospinning Polyvinylpyrrolidone (PVP) sound absorption Impedance tube

Studies on the sound absorption and transmission loss performances of wood-based, natural and wastematerials

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Acta Mechanica Sinica 2021年第5期37卷 861-873,I0003页

作者： Hsiao Mun Lee Wensheng Luo Jinlong Xie Guilin Wen Heow Pueh Lee Center for Research on Leading Technology of Special Equipment School of Mechanical and Electrical EngineeringGuangzhou UniversityGuangzhou 510006China School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China Department of Mechanical Engineering National University of SingaporeSingapore 117575Singapore

The sound absorption and sound transmission loss performances of the natural woods,hard and soft processed woods with attachment of the various natural orwastematerials were investigated in the present study using impedance tube with American Society for Testing Material(ASTM)*** sound absorption performances of all natural and all hard processed woods were very *** was found that filter mat made by the coconut fibre was the best material for sound absorption improvement of the hard processed *** sound absorption performance of the soft processed wood(cork)was better than all natural and all hard processed *** all tested woods,it was found that the cork with attached tea bag made by corn fibre is the best selection for sound absorption *** transmission loss performances of all natural woods were *** effects of various materials on the transmission loss performances of all hard processed woods were not very *** cork with and without attachment of various materials,their transmission loss performances were not as good as the hard processed *** all tested woods,it was found that Pterocarpus soyauxii and Quercus spp.(natural woods)are the best woods to be used in those applications when prevention of sound transmission is *** is recommended that cork is the best wood to be used in those applications where sound absorption and prevention of sound transmission are needed at the same time due to its good sound absorption performance while its ability on prevention of the sound transmission is also acceptable.

关键词： sound absorption Transmission loss Wood-based material Natural material Waste material

Customisable sound absorption properties of functionally graded metallic foams

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Journal of Materials Science & Technology 2022年第13期108卷 196-207页

作者： Jun Wei Chua Xinwei Li Tao Li Beng Wah Chua Xiang Yu Wei Zhai Department of Mechanical Engineering National University of Singapore117575Singapore Agency for Science Technology and Research(A^(*)STAR)Singapore Institute of Manufacturing Technology138634Singapore Agency for Science Technology and Research(A^(*)STAR)Engineering MechanicsInstitute of High-Performance Computing1 Fusionopolis Way138632Singapore

In this study,functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method,with open-cell polyurethane foams as a *** products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle *** absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam *** graded foam of two distinct pore sizes,a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves,thereby aiding in graded foam *** increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound *** sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is *** sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound *** the same composition of foam with a fixed thickness proportion of pore sizes,one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical *** study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications.

关键词： Template replication method Functionally graded foam sound absorption Transfer matrix method Composite metal foam

Multifunctional aramid nanofibers reinforced RGO aerogels integrated with high-efciency microwave absorption, sound absorption and heat insulation performance

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Journal of Materials Science & Technology 2022年第35期130卷 166-175页

作者： Qian Liu Liang Tang Jinzhe Li Yao Chen Zhengkang Xu Jiatong Li Xinyu Chen Fanbin Meng Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Shenzhen Institute of Southwest Jiaotong University Shenzhen 518000China

Although lightweight and three-dimensional(3 D) graphene aerogels are highly desirable for microwave absorption(MA) due to their high porosity,specific surface area,and 3 D conductive network,it still remains a large challenge to construct a multifunctional application framework to quickly adapt to the complex practical environment,making it to be efficiently applied in a variety of complex ***,multifunctional aramid nanofibers(ANFs) reinforced reduced graphene oxide aerogels(RGO@ANF) have been achieved by in-situ gel reaction,freeze-drying,and thermal annealing *** introduced ANFs in RGO aerogels can prevent the graphene sheets from over-stacking and enhance the connectivity of cell walls,thus leading to excellent compression resistance,MA,sound absorption,and thermal insulation *** 70% strain,the maximum compressive stress of RGO@ANF aerogel reaches78.8 kPa,and reversible compressibility with reliable resistance to fatigue for 100 compressive cycles at20% ***,the RGO@ANF aerogel exhibit a minimum reflection loss(RL_(min)) of-56.5 dB and a maximum effective absorption bandwidth(EAB) of 7.0 GHz at a thickness of 2.8 mm,basically covering the X and Ku ***,the hybrid aerogel exhibited excellent sound absorption with an average absorption coefficient> 0.56 at 2-6 kHz and good thermal insulation performance with low thermal conductivity of about 49.18 mW *** integrated graphene aerogels with such multifunctional performances hold a great promise for applications such as MA,sound absorption,and heat insulation.

关键词： Graphene-based aerogels Reversible Compressibility Microwave absorptio Heat insulation sound absorption

The vibroacoustic response and sound absorption performance of multilayer, microperforated rib-stiffened plates

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Acta Mechanica Sinica 2017年第5期33卷 926-941页

作者： Haian Zhou Xiaoming Wang Huayong Wu Jianbing Meng School of Mechanical Engineering Shandong University of Technology School of Mechanical Engineering Dalian University of Technology School of Aeronautics Shandong Jiaotong University

The vibroacoustic response and sound absorption performance of a structure composed of multilayer plates and one rigid back wall are theoretically analyzed. In this structure, all plates are two-dimensional, microperforated, and periodically rib-stiffened. To investigate such a structural system, semianalytical models of one-layer and multilayer plate structures considering the vibration effects are first developed. Then approaches of the space harmonic method and Fourier transforms are applied to a one-layer plate, and finally the cascade connection method is utilized for a multilayer plate structure. Based on fundamental acoustic formulas, the vibroacoustic responses of microperforated stiffened plates are expressed as functions of a series of harmonic amplitudes of plate displacement, which are then solved by employing the numerical truncation method. Applying the inverse Fourier transform, wave propagation, and linear addition properties, the equations of the sound pressures and absorption coefficients for the one-layer and multilayer stiffened plates in physical space are finally derived. Using numerical examples, the effects of the most important physical parameters-for example, the perforation ratio of the plate, sound incident angles, and periodical rib spacing-on sound absorption performance are examined. Numerical results indicate that the sound absorption performance of the studied structure is effectively enhanced by the flexural vibration of the plate in water. Finally, the proposed approaches are validated by comparing the results of stiffened plates of the present work with solutions from previous studies.

关键词： sound absorption Multilayer Microperforated Rib-stiffened Flexural Vibration

Dynamic flow resistivity based model for sound absorption of multi-layer sintered fibrous metals

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Science China(Technological Sciences) 2014年第11期57卷 2096-2105页

作者： MENG Han AO QingBo TANG HuiPing XIN FengXian LU TianJian State Key Laboratory for Mechanical Structure Strength and Vibration School of Aerospace Xi'an Jiaotong University State Key Laboratory of Porous Metal Materials Northwest Institute for Nonferrous Metal Research

The sound absorbing performance of the sintered fibrous metallic materials is investigated by employing a dynamic flow resistivity based model,in which the porous material is modeled as randomly distributed parallel fibers specified by two basic physical parameters:fiber diameter and porosity.A self-consistent Brinkman approach is applied to the calculation of the dynamic resistivity of flow perpendicular to the cylindrical *** on the solved flow resistivity,the sound absorption of single layer fibrous material can be obtained by adopting the available empirical ***,the recursion formulas of surface impedance are applied to the calculation of the sound absorption coefficient of multi-layer fibrous *** measurements are conducted to validate the proposed model,with good agreement achieved between model predictions and tested *** calculations with the proposed model are subsequently performed to quantify the influences of fiber diameter,porosity and backed air gap on sound absorption of uniform(single-layer)fibrous *** show that the sound absorption increases with porosity at higher frequencies but decreases with porosity at lower *** sound absorption also decreases with fiber diameter at higher frequencies but increases at lower *** sound absorption resonance is shifted to lower frequencies with air *** multi-layer fibrous materials,gradient distributions of both fiber diameter and porosity are introduced and their effects on sound absorption are *** is found that increasing the porosity and fiber diameter variation improves sound absorption in the low frequency *** model provides the possibility to tailor the sound absorption capability of the sintered fibrous materials by optimizing the gradient distributions of key physical parameters.

关键词： sound absorption sintered fibrous material dynamic flow resistivity

sound absorption performance of acoustic metamaterials composed of double-layer honeycomb structure

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Journal of Central South University 2021年第9期28卷 2947-2960页

作者： WANG Da XIE Su-chao YANG Shi-chen LI Zhen Key Laboratory of Traffic Safety on Track of Ministry of Education Changsha 410075China Joint International Research Laboratory of Key Technology for Rail Traffic Safety Changsha 410075China School of Traffic&Transportation Engineering Central South UniversityChangsha 410075China National Innovation Center of Advanced Rail Transit Equipment Zhuzhou 412001China

The purpose of the research is to assess the sound absorption performance(SAP)of acoustic metamaterials made of double-layer Nomex honeycomb structures in which a micro-orifice corresponds to a honeycomb *** this purpose,the influences of structural parameters on the SAP of acoustic metamaterials were investigated by using experimental testing and a validated theoretical *** addition,the sandwich structure was optimized by the genetic *** research shows that the panel thickness and micro-orifice diameter mainly affect the second resonant frequency and second peak sound absorption coefficient(SAC)of the *** unit cell size is found to influence the first and second resonant frequencies and two peaks of the *** extremely low side-length of the honeycomb core decreases the SAP of the structure for low-frequency noise ***,the sandwich structure presents a better SAP when the diameter of micro-orifices on the front micro-perforated panel(MPP)exceeds that of the back *** sandwich structure shows better noise reduction performance after the optimization aiming at the noise frequency outside trains.

关键词： acoustic metamaterials sound absorption honeycomb sandwich panel micro-perforated panel