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. 

scholarly journals Insulation Characteristics of Sisal Fibre/Epoxy Composites

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
A. Shalwan ◽  
M. Alajmi ◽  
A. Alajmi
Keyword(s):  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Thermal Characteristics ◽  
Fibre Volume ◽  
Point Of View ◽  
Natural Fibres ◽  
Epoxy Composites ◽  
Ongoing Research ◽  
Sisal Fibre ◽  
The Impact

Using natural fibres in civil engineering is the aim of many industrial and academics sectors to overcome the impact of synthetic fibres on environments. One of the potential applications of natural fibres composites is to be implemented in insulation components. Thermal behaviour of polymer composites based on natural fibres is recent ongoing research. In this article, thermal characteristics of sisal fibre reinforced epoxy composites are evaluated for treated and untreated fibres considering different volume fractions of 0–30%. The results revealed that the increase in the fibre volume fraction increased the insulation performance of the composites for both treated and untreated fibres. More than 200% insulation rate was achieved at the volume fraction of 20% of treated sisal fibres. Untreated fibres showed about 400% insulation rate; however, it is not recommended to use untreated fibres from mechanical point of view. The results indicated that there is potential of using the developed composites for insulation purposes.

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.

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 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 Experimental Study of Multi-Ribbed One-Way Composite Slabs Made of Steel Fibre, Foam, and Normal Concrete

2018 ◽  
Vol 64 (2) ◽  
pp. 79-96
Author(s):  
Yabo Wang ◽  
H. T. Liu ◽  
G. F. Dou ◽  
C. H. Xi ◽  
L. Qian
Keyword(s):  
Steel Fibre ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Load Capacity ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Sound Insulation ◽  
Normal Concrete ◽  
Composite Slabs ◽  
Reinforcement Configuration

Abstract This paper aims to study the effect of reinforcement configuration (steel fibre and rebar) on the mechanical performance of composite slabs of the same total steel contents. We manufactured four pieces of fullscale multi-ribbed composite prefabricated slabs with different reinforcement configurations by using steel fibrereinforced concrete, foam concrete, and normal concrete. The multi-ribbed composite prefabricated slab has many excellent properties, such as light weight, good thermal and sound insulation. Thus, it can be applied to fabricated structures. In addition, the composite prefabricated slabs with the same total steel contents but with different reinforcement configurations were studied under the same static load, and many technical indicators such as crack resistance capacity, yield load, ultimate load capacity, maximum deflection, destructive pattern, and stress of steel rebar were obtained. Results indicate reinforcement configuration has a significant effect on the mechanical performance of composite prefabricated slabs with the same total steel contents, and composite prefabricated slabs reinforced with longitudinal rebar and steel fibre (volume fraction is 1.5%) have the best mechanical performance and ductility.

scholarly journals SIFAT PENYERAPAN BUNYI PADA KOMPOSIT SERAT BATANG PISANG (SBP) – POLYESTER

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Khusnul Khotimah ◽  
Susilawati ◽  
Harry Soeprianto
Keyword(s):  
Absorption Coefficient ◽  
Physical Properties ◽  
Sound Absorption ◽  
Volume Fraction ◽  
Alkali Treatment ◽  
Sound Level ◽  
Sound Absorption Coefficient ◽  
Fiber Volume ◽  
The Matrix ◽  
Banana Stem

This research conducted to find the physical properties of the absorption of sound from banana stem fiber (Serat Batang Pisang/SBP) with polyesters’ matrix. The sound absorbent material made with a variety of different volume fraction composition. The comparison between the SBP and the volume fraction of the polyester is made of 30%: 70%, 40%: 60% and 50%: 50%. The method of research was done in three stages: making banana stem fiber, manufacturing composite and testing of composite SBP. Composite testing includes physical properties (sound absorption). Preparation of the samples started by taking a banana stem, decomposition banana stem fiber, alkali treatment with NaOH 4%, then mixing the SBP with the matrix  polyester. Manufactured the composites by press the materials on the molding for 12 hours, then tested to find physical properties. Sound absorption test performed using a signal generator and a sound level meter with the principle of the impedance tube method through acoustic box approach as a reference. The results of the study showed that SBP with polyester composite capable to absorb the sound with sound absorption coefficient α = 0.84 at 50% fiber volume fraction. Thus SBP composites can absorb sound for low and medium frequency, based on the standard ISO 11654:1997 (E) where the minimum of sound absorption coefficient of acoustic materials is α = 0.15. Keywords: Composite, banana stem fiber, sound absorber materials, polyester.

scholarly journals KARAKTERSTIK SERAPAN SUARA KOMPOSIT POLYESTER BERPENGUAT SERAT TAPIS KELAPA

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
I Made Astika ◽  
I Gusti Komang Dwijana
Keyword(s):  
Absorption Coefficient ◽  
Fiber Length ◽  
Sound Absorption ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Sound Absorption Coefficient ◽  
Fiber Volume ◽  
Absorption Frequency ◽  
Class D

The purpose of this study is to investigate of sound absorption of coconut filter fiber composites. The research material made with coconut filter fiber as reinforcement and matrix resin unsaturated polyester (UPRs) type Yukalac BQTN 157 with 1% hardener types MEKPO (Methyl Ethyl Ketone Peroxide) and fiber treatment by  0,5% KMnO4. Production methods is poltrusion and the variations of fiber volume fraction are 20, 25 and 30% and fiber length are 5, 10 and 15 mm. Testing of sound absorption frequency are 250, 500, 1000, 2000 and 4000 Hz. The results of research show that  the highest value of sound absorption coefficient is on  the composites with composition of 10 mm fiber length and 30% fiber volume fraction, that is 0.550828. The values are included in the class “Sound Absorption Coefficient Class D (Extremely absorbing)” with the range 0.40 – 0.60 based on ISO standard 11654:1997.

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