scholarly journals Sound-Absorption Coefficient of Bark-Based Insulation Panels

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1012 ◽  
Author(s):  
Eugenia Mariana Tudor ◽  
Anna Dettendorfer ◽  
Günther Kain ◽  
Marius Catalin Barbu ◽  
Roman Réh ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Residential Buildings ◽  
Coarse Grained ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Formaldehyde Resin ◽  
Frequency Interval ◽  
Spruce Bark

The objective of this study was to investigate the sound absorption coefficient of bark-based insulation panels made of softwood barks Spruce (Picea abies (L.) H. Karst.) and Larch (Larix decidua Mill.) by means of impedance tube, with a frequency range between 125 and 4000 Hz. The highest efficiency of sound absorption was recorded for spruce bark-based insulation boards bonded with urea-formaldehyde resin, at a level of 1000 and 2000 Hz. The potential of noise reduction of larch bark-based panels glued with tannin-based adhesive covers the same frequency interval. The experimental results show that softwood bark, an underrated material, can substitute expensive materials that involve more grey energy in sound insulation applications. Compared with wood-based composites, the engineered spruce bark (with coarse-grained and fine-grained particles) can absorb the sound even better than MDF, particleboard or OSB. Therefore, the sound absorption coefficient values strengthen the application of insulation panels based on tree bark as structural elements for the noise reduction in residential buildings, and concurrently they open the new ways for a deeper research in this field.

scholarly journals Effect of Thickness and Perforation Size on the Acoustic Absorption Performance of a Micro-Perforated Panel

2021 ◽  
Vol 335 ◽  
pp. 03016
Author(s):  
Yi-San Wong ◽  
Vignesh Sekar ◽  
Se Yong Eh Noum ◽  
Sivakumar Sivanesan
Keyword(s):  
Absorption Coefficient ◽  
Urban Areas ◽  
Sound Absorption ◽  
Rapid Development ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Absorption ◽  
Psychological Disturbance ◽  
Absorption Performance

In current times, noise pollution is especially apparent in urban areas due to rapid development in transportation, industrialization, and urbanization. The worsening noise pollution is detrimental to human health and behaviour as it can contribute to disorders and psychological disturbance. Thus, noise regulation is crucial and must be addressed with immediate effect. Micro-perforated panels (MPP) can be a potential solution to mitigate noise on a commercial scale. Researchers have addressed the mechanics behind the enhancement of acoustic absorption through micro-perforation and some suggestions have been made, such as the effect of structural variation on sound absorption performance. Hence, this research aims at optimizing the sound absorption performance of an MPP by determining the connection between thickness and perforation size with sound absorption coefficient. Three cases were considered: (i) varying perforation size, (ii) varying thickness, and (iii) varying perforation size and thickness simultaneously. Based on the Maa prediction model, the sound absorption performance for all three cases have been simulated through the MATLAB software. Results show that the increase in both thickness and perforation size together increases the peak value of sound absorption coefficient (SAC). It also shifts the peak towards the higher frequency region and narrows the bandwidth. The findings of this study indicate the potential of thick MPPs as commercial sound absorbers by adjusting the size of perforations. Thicker and sturdier MPPs with optimal acoustic resistance and reactance can act as reliable sound absorbers for sound insulation purposes.

scholarly journals Mathematical model of acoustic characteristics of polyurethane foam used for sound absorption in aerospace engineering

2021 ◽  
Vol 20 (2) ◽  
pp. 53-62
Author(s):  
A. V. Kuznetsov ◽  
A. A. Igolkin ◽  
A. I. Safin ◽  
A. O. Pantyushin
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Absorption Coefficient ◽  
Finite Element Modeling ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Space Technology ◽  
Acoustic Characteristics ◽  
Element Modeling

When solving the problem of reducing the acoustic load on the spacecraft during the launch and flight of the launch vehicle, finite element modeling of acoustic processes under the nose fairing is carried out. To successfully solve this problem, a mathematical model of the acoustic characteristics of the material used for sound insulation is required. The existing mathematical models of the acoustic characteristics of materials are not suitable for the material under consideration that can be used in rocket and space technology to increase the sound insulation of the payload fairing + transfer compartment assembly. To obtain the sound absorption coefficient of the material, an impedance tube measurement method with two microphones is used. Using the method of differential evolution, the coefficients of a mathematical model of acoustic characteristics of the Delany-Bazley type for the specified material are selected. The sound absorption coefficient obtained experimentally and that calculated using the obtained model are compared; the average and maximum values of the error are shown. The resulting model will make it possible to carry out finite element modeling of acoustic and vibroacoustic processes under the nose fairing, taking into account the location of the sound-absorbing material.

scholarly journals Sound Absorption Coefficient of Different Green Materials Polymer on Noise Reduction

2020 ◽  
Vol 9 (3) ◽  
pp. 2773-2777
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
New Technologies ◽  
Raw Materials ◽  
Agricultural Waste ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Green Materials

One of the sources of noise pollution to environment is from the consumption of electrical and mechanical appliances usage at home and industries. Growth development and advancement of heavy equipment in construction work further emphasize the necessity used of new technologies for noise reduction. The best technique of control or reducing of noise is by using the materials that can absorb the noise by materials itself. Potential materials from agricultural waste as sound absorber were identified. There are two main objectives in this study; First is to produce acoustic absorber by using natural materials. Second is to identify their sound absorption coefficients. The samples were fabricated using the raw materials from banana stem, grass, palm oil leaves and lemongrass mixed with binding agents of polyurethane and hardener to the ratio of 1:4. The diameters of the samples consist of 28mm and 100mm and the thickness is 10mm. The samples sound absorption coefficients were measured according to standards ASTM E1050-98 / ISO 105342-2 (Impedance tube method). Sound absorption coefficient of the materials depends on frequencies choose. The frequencies values used in this study were in the range from 500Hz to 4500Hz. Material made from grass have a higher average sound absorption coefficient value which is 0.553. All tested samples also can be categories under class D type of materials based on sound absorption coefficient value.

Exploration and optimization on the usage of micro-perforated panels as trim panels in commercial aircrafts

2020 ◽  
Vol 68 (1) ◽  
pp. 87-100
Author(s):  
L.I. Chenxi ◽  
H.U. Ying ◽  
H.E. Liyan
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Absorption Coefficient ◽  
Aviation Industry ◽  
Sound Insulation ◽  
Aircraft Cabins ◽  
Aircraft Cabin ◽  
Specific Frequency ◽  
Trim Panel

Micro-perforated panels (MPPs), as an alternative to porous materials for sound absorption, have been commonly used in electronic industries and aircraft engines but are barely used in aircraft cabins. The effect of MPPs on the sound insulation and absorption properties of aircraft cabin panels has been investigated in this article. Theoretical modeling has been conducted on an aircraft cabin panel structure with a trim panel replaced by an MPP trim panel, using the transfer matrix method and the classic MPP theory. It is indicated by the theoretical results that, although the sound transmission loss (STL) of the cabin panel with an MPP trim panel is lower than that with an un-perforated panel, the MPP trim panel can significantly enhance the sound absorption coefficient of the entire cabin panel structure. Based on the well-developed MPP theory, the sound absorption coefficient of an aircraft cabin panel with an MPP trim panel can be improved by optimizing the MPP's parameters at a specific frequency. Taking an engine frequency 273 Hz as an example, the optimization can increase the sound absorption coefficient to 1 by using the doublelayered MPPs. When the thermal acoustic insulation blanket is considered, although the STL of the proposed structure with double-layered MPP trim panels in a diffuse field is lower than those without MPP trim panels, the sound absorption in the cabin is significantly enhanced due to the double-layer MPP trim panel at the specific engine frequency and across all frequencies. The STL of the structure with double-layered MPP trim panels and TAIB can be higher than 40 dB from 880 Hz in a diffuse field, which implies its effectiveness as sound insulation structure in aviation industry. MPP trim panels provide a new idea for the design of aircraft cabin panels and areworthy of further research

scholarly journals The Sound Absorption Coefficient of Railway Concrete Sleepers Containing Palm Oil Fuel Ash (POFA) As a Cement Replacement Material

2021 ◽  
Vol 2129 (1) ◽  
pp. 012032
Author(s):  
Nurfarhanna Ahmad Sulaiman ◽  
Suraya Hani Adnan ◽  
Abdul Hadi Izaan ◽  
Mohamad Hairi Osman ◽  
Mohamad Luthfi Ahmad Jeni ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Palm Oil ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Palm Oil Fuel Ash ◽  
Noise And Vibration ◽  
Fuel Ash ◽  
Reduction Coefficient ◽  
Oil Fuel

Abstract Major noise and vibration during train operation can cause disturbance to the surrounding. One of the methods to reduce this disturbance are by installing concrete sleepers. The use of railway concrete sleepers may be a high potential to reduce the noise and vibration. To produce concrete sleepers cement usage will be used with greater volume. Approximately 100 million tons of Palm Oil Fuel Ash (POFA) was disposed to the landfill currently. POFA contains high silica content and porous particles which indicated its pozzolanic properties and sound absorption characteristics. Therefore, this study was to determine the sound absorption coefficient of railway concrete sleepers containing POFA as a cement replacement material. Concrete sleepers with a strength grade of 55 and a w/c ratio of 0.35 were prepared in this study. Three design mixes with 0% (control), 20%, and 40% of POFA tested by using an impedance tube test at 28 days of curing age. The results show, the sound absorption coefficient and noise reduction coefficient increases as the percentage of POFA increases. The best performance was obtained by concrete sleepers containing 40% of POFA, with a recorded sound absorption coefficient of 0.10 for low frequency and 0.44 for high frequency. Meanwhile, the noise reduction coefficient recorded was 0.33, which reduce 32% of noise compared to OPC.

Effect of microfiber layers on acoustical absorptive properties of nonwoven fabrics

2019 ◽  
Vol 50 (3) ◽  
pp. 312-332 ◽  
Author(s):  
Gajanan Bhat ◽  
Magdi El Messiry
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Decisive Role ◽  
Mineral Wool ◽  
Acoustic Energy ◽  
Sound Absorption Coefficient ◽  
Nonwoven Materials ◽  
Reduction Coefficient ◽  
Melt Blown Nonwoven

There are several types of sound absorptive materials, such as natural and synthetic fibers, acoustic mineral wool, acoustic polyester panels, acoustic foam, cotton batts, that reduce the acoustic energy of a sound wave as the wave passes through. In this work, the use of nonwoven materials made of cotton, polyester, and polypropylene fibers for the development of sound absorptive nonwoven materials has been investigated. Samples of different materials (cotton, cotton/polyester blend, polyester fibers needle punched, and polypropylene melt blown nonwoven) and multilayer structures were tested on the designed impedance tube. Acoustic absorption properties of the fiber assemblies were studied in the frequency region of 100–1500 Hz. The values of sound absorption coefficient for different samples indicated that polypropylene microfiber melt blown nonwoven sample displayed a good sound absorption behavior in the entire frequency range. The use of multilayer samples improves the sound absorption coefficient with the condition that one of the layers is a thin melt blown nonwoven layer. The formation of nonwoven absorbent material consisted of hybrid layers, significantly reduces the resultant average sound absorption coefficient, especially when the upper layer is made from finer fibers of melt blown nonwoven of low air permeability value, and in this case the improvement reaches 50%. The use of melt blown layers of fine fibers values of noise reduction coefficient may reach 0.8. The multilayer nonwoven sound absorber design should take into consideration specific noise reduction coefficient values, not the absolute ones, particularly when the weight of the absorber is playing a decisive role.

SOUND ABSORPTION COEFFICIENT OF NATURAL FIBRES HYBRID REINFORCED POLYESTER COMPOSITES

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Abdul Hakim Abdullah ◽  
Afiqah Azharia ◽  
Farrahshaida Mohd Salleh
Keyword(s):  
Absorption Coefficient ◽  
High Frequency ◽  
Sound Absorption ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Natural Fibres ◽  
Sound Absorption Coefficient ◽  
Function Technique ◽  
Sound Insulation

Natural fibres have been known of its good acoustic damping properties and therefore, these materials could be used as a sound insulation in many applications. The main purpose of this investigation is to analyze the sound absorption coefficient of sugarcane baggase fibre, banana fibre and its hybrid based composites under various fibre volume fractions. Bone dry test specimens of 10%, 20% and 30% fibre volume fraction were treated with sodium hydroxide (NaOH) prior to composites fabrication using polyester as binder. The pre-tested specimens were examined using scanning electron microscope and electronic analytical balance to analyze physical and dimension characteristic. The sound absorption frequencies were measured using by the two-microphone transfer function technique in the impedance tube that has a 100 mm diameter for low frequency and 28 mm for high frequency, 0 Hz to 4000 Hz respectively. The result indicated that in low and high frequency, the combination of different natural fibres produced better sound absorption coefficient rather than using the natural fibre as individual. The results also demonstrated that the higher amounts of fibre volume fraction are affecting frequencies broadening, hence promising better sound absorbing capacity. 

Sound absorption of weft knitted fabrics: influence of fibers cross-section shape, stitch density and mechanical modification of surface

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad-Reza Saffari ◽  
Mehdi Kamali Dolatabadi ◽  
Abosaeed Rashidi ◽  
Mohammad Esmail Yazdanshenas
Keyword(s):  
Absorption Coefficient ◽  
Cross Section ◽  
Cross Sections ◽  
Sound Absorption ◽  
Structural Parameters ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Knitted Fabrics ◽  
Content Type ◽  
Fiber Cross Section

PurposeOne of the recent applications of fabrics is to use them for sound insulation. Accordingly, due to their low production cost and low relative density, fabrics have drawn attention in some of the industries such as the automotive and aircraft industries. The present study is aimed to investigate the effects of the fiber cross-section, porosity, thickness of samples and fuzzing of the knitted fabric on the sound absorption coefficient.Design/methodology/approachIn the present study, fabrics with three different stitch densities were knitted by yarns consist of three different forms of fiber cross-section shapes (circular, elliptical and plus-shaped). In this work, the sound absorption coefficient of knitted fabrics was investigated with regard to the different fiber cross-sections and structural parameters using an impedance tube.FindingsAs indicated by the obtained results, the cross-section, porosity, thickness and mass per unit area of the fabrics were the determinant factors for the sound absorption coefficient. In addition to, the sound absorption coefficient and porosity were shown to have an inverse relationship.Originality/valueA section of the present paper has been allocated to the investigation of the effect of the fiber cross-section and fuzzing of fabric on the sound absorption of plain knitted fabrics.

scholarly journals SOUND ABSORPTION OF SOUND SUPRESSING LIGHTWEIGHT STRUCTURED PANELS

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 40-43
Author(s):  
Valery Murzinov ◽  
Pavel Murzinov ◽  
Sergey Popov ◽  
Julia Taratinova
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Characteristics ◽  
Absorbing Materials

Description of the effective soundproofing panel is presented. For this panel, the ratio of acoustic characteristics and surface density exceeds many modern sound insulation and sound absorbing materials and structures. This article is devoted to modeling the sound absorption coefficient of the soundproof panel. The article presents formulas for determining the coefficient of sound absorption. Construction of a sound suppressed lightweight structured panel (SSLSP) developed by the authors is shown. Comparison of the effectiveness of the SSLSP panel and modern sound-proof materials is shown.

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