Acoustic characterization of membranes attached to sound absorbing base materials

The use of membranes attached to sound absorbing materials, with the aim of modifying its absorption properties, is quite a usual practice in acoustic conditioning applications. The behavior of the final composition formed by the sound absorbing base material and the attached membrane can serve to characterize the effect of the membrane, if the properties of the base material are known. This can be of great interest for several reasons. Firstly, the difficulty to characterize the materials separately, due to the thinness of the membranes. Secondly, the effect of the binding method used between the absorbing material and the membrane (glue, seams, etc.) can modify the properties of the membrane. This work presents a model that enables us to determine the acoustic impedance of the membranes from an initial analysis of the base material and a second analysis of the composition formed by the base material with the membrane. These analyses are carried out in an impedance tube by following the ISO 10534-2 standard and the results obtained allow modeling the attached membrane effect.

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Influence of Welding Process on the Microstructure of Carbon Steel and Stainless Steel Heterogeneous Welded Joints

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1138.31 ◽

2016 ◽

Vol 1138 ◽

pp. 31-36

Author(s):

Maria Cristina Dijmarescu ◽

Dumitru Titi Cicic ◽

Corneliu Rontescu ◽

Gheorhe Solomon

Keyword(s):

Chemical Composition ◽

Carbon Steel ◽

Structural Characterization ◽

Base Material ◽

Welding Process ◽

Cored Wire ◽

Base Materials ◽

Flux Cored Arc Welding ◽

Welded Seam

The reactions of the base material, during the welding process, consist in chemical composition, volume, structure and granulation changes. There are multiple problems which can occur by welding two steels with totally different chemical composition, i.e. carbon steel S235JR + AR and austenitic stainless X2CrNiMo17-12-2. The process used for making the heterogeneous joint was flux cored arc welding (FCAW), numerically coded 136. The paper presents the effects of welding through heat input, on the structural characterization of welded seam and heat affected zone. It also focuses on the structural characterization of the welded joint obtained using the flux cored wire T 23 12 L P C/M 1, and determining how the base materials participate at the formation of the welding joint.

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Diffusion Bonding of Ti6Al4V to Al2O3 Using Ni/Ti Reactive Multilayers

Metals ◽

10.3390/met11040655 ◽

2021 ◽

Vol 11 (4) ◽

pp. 655

Author(s):

Marcionilo Silva ◽

Ana S. Ramos ◽

M. Teresa Vieira ◽

Sónia Simões

Keyword(s):

Thin Films ◽

Diffusion Bonding ◽

Mechanical Characterization ◽

Base Material ◽

Microstructural Characterization ◽

Multilayer Thin Films ◽

X Ray ◽

Distribution Maps ◽

Base Materials

This paper aims to investigate the diffusion bonding of Ti6Al4V to Al2O3. The potential of the use of reactive nanolayered thin films will also be investigated. For this purpose, Ni/Ti multilayer thin films with a 50 nm modulation period were deposited by magnetron sputtering onto the base materials. Diffusion bonding experiments were performed at 800 °C, under 50 MPa and a dwell time of 60 min, with and without interlayers. Microstructural characterization of the interface was conducted through scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The joints experiments without interlayer were unsuccessful. The interface is characterized by the presence of a crack close to the Al2O3 base material. The results revealed that the Ni/Ti reactive multilayers improved the diffusion bonding process, allowing for sound joints to be obtained at 800 °C for 60 min. The interface produced is characterized by a thin thickness and is mainly composed of NiTi and NiTi2 reaction layers. Mechanical characterization of the joint was assessed by hardness and reduced Young’s modulus distribution maps that enhance the different phases composing the interface. The hardness maps showed that the interface exhibits a hardness distribution similar to the Al2O3, which can be advantageous to the mechanical behavior of the joints.

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Characterization of Carrageenan Edible films Plasticized with Glycerol

Jurnal Pengolahan Hasil Perikanan Indonesia ◽

10.17844/jphpi.v20i2.17499 ◽

2017 ◽

Vol 20 (2) ◽

pp. 219 ◽

Cited By ~ 3

Author(s):

Arham Rusli ◽

M. Metusalach ◽

Mulyati Muhammad Tahir

Keyword(s):

Moisture Content ◽

Film Thickness ◽

Physical Characteristic ◽

Base Material ◽

Edible Films ◽

Physical Characteristics ◽

Edible Film ◽

Base Materials ◽

Film Characteristics

Concentration of base materials and plasticizers used in the formulation of edible film was believed to affect physical characteristics of the film. The objectives of this study were to evaluate the effects of base material (carrageenan) and plasticiser (glycerol) concentrations on the characteristics of edible films produced and to determine the best concentrations of these two components based on the physical characteristics of the films. The experiment was conducted using a completely randomized factorial design with triplicated. The treatments applied were the concentrations of carrageenan (1%, 2%, and 3% (w/v)) and glycerol (5%, 10%, and 15% (w/w)). The results showed that carrageenan and glycerol concentrations used in the formulation of edible film affect the edible film characteristics. Film thickness and moisture content were significantly influenced by carrageenan and glycerol concentrations, while film elongation was only affected by carrageenan concentration. The best physical characteristic of the edible films was obtained when carrageenan and glycerol concentrations were 3% and 10% respectively.

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Microstructural Characterization of Dissimilar Titanium Alloys Joints Using Ni/Al Nanolayers

Metals ◽

10.3390/met8090715 ◽

2018 ◽

Vol 8 (9) ◽

pp. 715 ◽

Cited By ~ 3

Author(s):

Sónia Simões ◽

Filomena Viana ◽

Ana Ramos ◽

M. Vieira ◽

Manuel Vieira

Keyword(s):

Titanium Alloys ◽

Diffusion Bonding ◽

Base Material ◽

Microstructural Characterization ◽

Thin Layers ◽

Electron Microscopies ◽

Base Materials ◽

Material Surfaces ◽

Scanning Electron

This study demonstrates the potential of the use of Ni/Al nanolayers for joining dissimilar titanium alloys. For this purpose, a detailed microstructural characterization of the diffusion bonding interfaces of TiAl to Ti6Al4V, TiAl to TiNi and TiNi to Ti6Al4V was carried out. The nanolayers (alternated aluminum and nickel (Ni-7V wt.%) layers) were deposited onto the base material surfaces. Diffusion bonding was performed at 700 and 800 °C under pressures ranging from 5 to 40 MPa and at dwell times between 60 and 180 min. Microstructural characterization was performed using high resolution transmission and scanning electron microscopies. The results revealed that dissimilar titanium joints (TiAl to Ti6Al4V, TiAl to TiNi and TiNi to Ti6Al4V) assisted by Ni/Al nanolayers can be obtained successfully at 800 °C for 60 min using a pressure of 20 MPa. The bond interfaces are thin (less than 10 µm) and mainly composed of NiAl grains with a few nanometric grains of Al8V5. Thin layers of Al-Ni-Ti intermetallic compounds were formed adjacent to the base materials due to their reaction with the nanolayers.

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Acoustic Characterization of Marine Sediments

10.21236/ada627576 ◽

1997 ◽

Author(s):

Anatoliy N. Ivakin ◽

Darrell R. Jackson

Keyword(s):

Marine Sediments ◽

Acoustic Characterization

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Low temperature acoustic characterization of PMN single crystal

Journal of Applied Physics ◽

10.1063/1.5000361 ◽

2017 ◽

Vol 122 (8) ◽

pp. 084103 ◽

Cited By ~ 1

Author(s):

E. Smirnova ◽

A. Sotnikov ◽

S. Ktitorov ◽

H. Schmidt

Keyword(s):

Low Temperature ◽

Single Crystal ◽

Acoustic Characterization

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Acoustic characterization of silica nanoparticle-impregnated Kevlar fabric

Textile Research Journal ◽

10.1177/00405175211023812 ◽

2021 ◽

pp. 004051752110238

Author(s):

Oluwafemi P Akinmolayan ◽

James M Manimala

Keyword(s):

Transmission Loss ◽

Silica Nanoparticle ◽

Air Gap ◽

Thin Plates ◽

Residual Porosity ◽

Ballistic Performance ◽

Number Of Layers ◽

Structural Applications ◽

Acoustic Characterization

Silica nanoparticle-impregnated Kevlar (SNK) fabric has better specific ballistic performance in comparison to its neat counterparts. For multifunctional structural applications using lightweight composites, combining this improved ballistic functionality with an acoustic functionality is desirable. In this study, acoustic characterization of neat and SNK samples is conducted using the normal-incidence impedance tube method. Both the absorption coefficient and transmission loss (TL) are measured in the 60–6000 Hz frequency range. The influence of parameters such as number of layers of neat or treated fabric, percentage by weight of nanoparticle addition, spacing between fabric layers, and residual porosity is examined. It is found that while absorption decreases with an increase in nanoparticle addition for frequencies above about 2500 Hz, increasing the number of layers shifts peak absorption to lower frequencies. By introducing an air-gap behind the fabric layer, dominant low-frequency (1000–3000 Hz) absorption peaks are obtained that correlate well with natural modes of mass-equivalent thin plates. Examining the influence of residual porosity by laminating the SNK samples reveals that it contributes to about 30–50% of the total absorption. Above about 1500 Hz, 3–5 dB of TL increase is obtained for SNK samples vis-à-vis the neat samples. TL is found to increase beyond that of the neat sample above a threshold frequency when an air-gap is introduced between two SNK layers. With an increase in the weight of nanoparticle addition, measured TL tends to be closer to mass law predictions. This study demonstrates that SNK fabric could provide improved acoustic performance in addition to its ballistic capabilities, making it suitable for multifunctional applications and could form the basis for the development of simplified models to predict the structural acoustic response of such nanoparticle–fabric composites.

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Acoustic Characterization of Some Steel Industry Waste Materials

Applied Sciences ◽

10.3390/app11135924 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5924

Author(s):

Elisa Levi ◽

Simona Sgarbi ◽

Edoardo Alessio Piana

Keyword(s):

Thermal Characteristic ◽

Environmental Benefits ◽

Acoustic Properties ◽

Physical Parameters ◽

Industry Waste ◽

Acoustic Characterization ◽

Minimization Procedure ◽

The Difference ◽

By Products

From a circular economy perspective, the acoustic characterization of steelwork by-products is a topic worth investigating, especially because little or no literature can be found on this subject. The possibility to reuse and add value to a large amount of this kind of waste material can lead to significant economic and environmental benefits. Once properly analyzed and optimized, these by-products can become a valuable alternative to conventional materials for noise control applications. The main acoustic properties of these materials can be investigated by means of a four-microphone impedance tube. Through an inverse technique, it is then possible to derive some non-acoustic properties of interest, useful to physically characterize the structure of the materials. The inverse method adopted in this paper is founded on the Johnson–Champoux–Allard model and uses a standard minimization procedure based on the difference between the sound absorption coefficients obtained experimentally and predicted by the Johnson–Champoux–Allard model. The results obtained are consistent with other literature data for similar materials. The knowledge of the physical parameters retrieved applying this technique (porosity, airflow resistivity, tortuosity, viscous and thermal characteristic length) is fundamental for the acoustic optimization of the porous materials in the case of future applications.

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