scholarly journals Improvement of the sound absorption performance of jute felt-based sound absorbers using micro-perforated panels

2017 ◽  
Vol 36 (4) ◽  
pp. 376-398 ◽  
Author(s):  
Pritesh V Bansod ◽  
T Sai Teja ◽  
Amiya R Mohanty
Keyword(s):  
Transfer Matrix Method ◽  
Sound Absorption ◽  
Low Cost ◽  
Control Engineering ◽  
Natural Materials ◽  
Sound Absorber ◽  
Absorbing Materials ◽  
Different Types ◽  
Absorbing Material ◽  
Absorption Performance

In industrial and architectural applications, noise can be controlled using sound-absorbing materials. Natural materials are now gaining importance in the noise control engineering as they have advantages like low cost, eco-friendly, easy to produce, etc. Jute is one of such natural materials, which can be used as a sound-absorbing material. Micro-perforated panels along with three different types of jute felts are used in a multilayer sound absorber configuration to improve its sound absorption. The sound absorption performance of these multilayer sound absorbers is evaluated by using the transfer matrix method and experimental method. Dependence of sound absorption performance on the placement of micro-perforated panels in a multilayer sound absorber is also studied. It is observed that the sound absorption performance depends on the position of micro-perforated panels in a multilayer sound absorber.

scholarly journals Sound-Absorption Properties of Materials Made of Esparto Grass Fibers

2020 ◽  
Vol 12 (14) ◽  
pp. 5533 ◽  
Author(s):  
Jorge P. Arenas ◽  
Romina del Rey ◽  
Jesús Alba ◽  
Roberto Oltra
Keyword(s):  
Sound Absorption ◽  
Natural Fibers ◽  
Normal Incidence ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
Absorption Performance ◽  
Sustainable Materials ◽  
Reasonable Prediction ◽  
Best Fit

Research on sound-absorbing materials made of natural fibers is an emerging area in sustainable materials. In this communication, the use of raw esparto grass as an environmentally friendly sound-absorbing material is explored. Measurements of the normal-incidence sound-absorption coefficient and airflow resistivity of three different types of esparto from different countries are presented. In addition, the best-fit coefficients for reasonable prediction of the sound-absorption performance by means of simple empirical formulae are reported. These formulae require only knowledge of the airflow resistivity of the fibrous material. The results presented in this paper are an addition to the characterization of available natural fibers to be used as alternatives to synthetic ones in the manufacturing of sound-absorbing materials.

Radar Absorbing Materials Based on Metamaterials

2010 ◽  
Vol 75 ◽  
pp. 215-223
Author(s):  
Andrey Nikolayevich Lagarkov ◽  
Vladimir Nikolayevich Kisel ◽  
Vladimir Nikolayevich Semenenko
Keyword(s):  
Electromagnetic Wave ◽  
Reflection Coefficient ◽  
Frequency Band ◽  
Radar Absorbing Material ◽  
Wide Range ◽  
Absorbing Materials ◽  
Different Types ◽  
Absorbing Material ◽  
Wave Incidence

The use of metamaterial for design of radar absorbing material (RAM) is discussed. The typical features of the frequency dependencies of , , ,  of composites manufactured of different types of resonant inclusions are given as an example. The RAM characteristics obtained by the use of the composites are given. It is shown that it is possible to use for RAM design the metamaterials with both the positive values of ,  and negative ones. Making use of the frequency band with negative  and  it is possible to create a RAM with low reflection coefficient in a wide range of the angles of electromagnetic wave incidence.

scholarly journals A Preliminary Study on Acoustical Performance of Oil Palm Mesocarp Natural Fiber

2015 ◽  
Vol 773-774 ◽  
pp. 247-252 ◽  
Author(s):  
Hanif Abdul Latif ◽  
Musli Nizam Yahya ◽  
Mohamed Najib Rafiq ◽  
Mathan Sambu ◽  
Mohd Imran Ghazali ◽  
...  
Keyword(s):  
Oil Palm ◽  
Sound Absorption ◽  
Natural Fiber ◽  
Standard Test ◽  
Air Gap ◽  
Test Method ◽  
Synthetic Materials ◽  
Absorbing Material ◽  
Absorption Performance ◽  
Impedance Tube Method

As the population increases, the demand of a comfortable environmental such as sound pollution is getting higher. Sound pollutions also have become worsen and creating concerns for many peoples. Due to this problem, synthetic materials as acoustic absorbers still applied as commonly acoustical panels and this material may hazardous to human health and contribute significantly a pollution to the environments. However, researchers have interested in conducting their research on natural fiber to be an alternative sound absorber. This study investigated the potential of oil palm Mesocarp fiber for sound absorbing material. The Mesocarp fibers were mixed with polyurethane (PU) as binder with ratio of 70:30. The thickness was varied in 10mm, 20mm, 30mm, and 40mm. This study also investigated the air gap of 5mm and 10mm in the sound absorption performance. Impedance Tube Method was used to measure sound absorption coefficient (a). The measurement was done on accordance with ASTM E1050-98, which is the standard test method for impedance and absorption of acoustical materials using a tube. The results showed that the optimum value for Mesocarp fiber is 0.93. The optimum value obtained at 5000 Hz. The influence of air gap increases the sound absorption especially from 250 Hz to 4000 Hz. These results indicate that fiber from Mesocarp is promising to be used sound absorbing material.

Modelling the Effect of Flexural Vibration on Sound Absorption of a Micro-Perforated Panel Using Wave Propagation Method

2013 ◽  
Vol 471 ◽  
pp. 255-260
Author(s):  
Azma Putra ◽  
Muhammad Sajidin Py ◽  
Norliana Salleh
Keyword(s):  
Wave Propagation ◽  
Sound Absorption ◽  
Flexural Vibration ◽  
Rigid Wall ◽  
Flexural Wave ◽  
Wave Propagation Method ◽  
Rigid Condition ◽  
Absorbing Material ◽  
Absorption Performance ◽  
Propagation Technique

Micro-perforated panel (MPP) is well known as the alternative green sound absorbing material replacing the synthetic porous absorber. Several works have been established which model the sound absorption performance of the MPP with various arrangements. However, most existing models are for MPP with rigid condition and rarely discuss the effect of vibration due to the impinging sound. In this paper, a simple approach using wave propagation technique is proposed to take into account the effect of flexural wave in the MPP on its sound absorption. The model begins with an MPP coupled with a solid panel separated by an air gap. The impedance of the back solid panel can then be adjusted to a very large value to simulate a rigid wall.

scholarly journals The influence of the distribution of sound absorbing materials on the estimation of reverberation time in rooms

2018 ◽  
Vol 49 ◽  
pp. 00078
Author(s):  
Marcelina Olechowska ◽  
Artur Nowoświat ◽  
Jan Ślusarek ◽  
Mateusz Latawiec
Keyword(s):  
Absorption Coefficient ◽  
Acoustic Field ◽  
Sound Absorption ◽  
Sound Field ◽  
Reverberation Time ◽  
Type D ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
Different Dimensions ◽  
Materials Used

Reverberation time in rooms depends on many factors, e.g. cubature, surface of envelopes, sound absorption coefficient of materials used for the construction of the envelopes, geometry of rooms or the distribution of sound absorbing materials. The arrangement of sound absorbing materials in rooms has an impact on the dispersion of acoustic field, yet theoretical calculation models do not take into account this impact. According to these models, regardless of the arrangement of sound absorbing materials, the reverberation time in a room will remain unchanged. The present paper investigates the above problem by means of computer simulations. For the needs of the simulation, three rooms with different dimensions were adopted, i.e. type 'p' - a cuboidal room with a square base, type 'd' - a cuboidal room (with one side of the 'p' room lengthened), type 'w' - a cuboidal room (with the height of the room lengthened 'p'). During the simulation, the way of acoustic field dispersion was being changed and its influence on the reverberation time in the rooms was being determined. The authors investigated two situations. The first one involved a non-dampened room, in which the sound absorbing material was being arranged differently. The second one involved a welldampened room, and the dispersion of sound field was analyzed depending on the location of the reflecting material.

scholarly journals Rating of Sound Absorption for EFBMF Acoustic Panels according to ISO 11654:1997

2018 ◽  
Vol 150 ◽  
pp. 03002 ◽  
Author(s):  
Emedya Murniwaty Samsudin ◽  
Lokman Hakim Ismail ◽  
Aeslina Abd Kadir ◽  
Ida Norfaslia Nasidi ◽  
Noor Sahidah Samsudin
Keyword(s):  
Sound Absorption ◽  
Empty Fruit Bunch ◽  
Initial Thickness ◽  
Reverberation Chamber ◽  
Sound Absorber ◽  
Class A ◽  
Class B ◽  
Absorption Performance

Empty fruit bunch fibre (EFB) and mesocarp fibre (MF) have been used in the fabrication of a new acoustic panel as a sound absorber for building. Measurements were carried out following ISO 354 in the mini reverberation chamber and the sound absorption performance of EFBMF acoustic panels were rated based on ISO 11654. Measurements of the new EFBMF acoustic panel involves five panel designs of 100 EFB dust panels, 80:20 dust panels, 100MF coir panels, 90:10 coir panels and 50:50 coir panels with 5 cm of initial thickness. Results showed that 100MF coir panel achieved αw of 0.90 coefficient and was rated as Class A absorber followed by 90:10 coir panels with αw of 0.85 coefficient and 100 EFB dust, 80:20 dust and 50:50 coir panels having αw of 0.80 coefficients and been rated as Class B absorber. This research has successfully defined that EFB and MF are viable to be used as raw fibre for acoustic absorber for building.

New Oil-Absorbing Material

2011 ◽  
Vol 287-290 ◽  
pp. 667-670
Author(s):  
Yan Jin Shi ◽  
Yan Feng
Keyword(s):  
Water Pollution ◽  
Research And Development ◽  
High Efficiency ◽  
Low Cost ◽  
Ecological Environment ◽  
Environment Protection ◽  
Production Methods ◽  
Development Direction ◽  
Absorbing Materials ◽  
Absorbing Material

With the development of industry, water pollution is increasingly severe. The research and development of oil-absorbing materials plays an important role in solving the ecological environment protection. Various oil-absorbing materials are introduced. Then, the new oil-absorbing materials are introduced mainly, including classification, production methods, oil-absorbing mechanism and properties. The limitations of the new oil-absorbing materials are pointed. And the development direction of oil-absorbing materials should be toward the high efficiency, low-cost, environmentally friendly and biodegradable.

A Compact Hybrid Sound Absorber Using Flexible Micro-Perforated Panel and Piezoelectric Actuator

2013 ◽  
Vol 325-326 ◽  
pp. 8-11
Author(s):  
Wei Guang Zheng ◽  
Ying Feng Lei ◽  
Qi Bai Huang ◽  
Chuan Bing Li
Keyword(s):  
Hybrid System ◽  
Piezoelectric Actuator ◽  
Sound Absorption ◽  
Low Frequency ◽  
Combined Approach ◽  
High Frequencies ◽  
Sound Absorber ◽  
Vibration Effect ◽  
Piezoelectric Patch ◽  
Absorption Performance

This paper presents the concept of a compact hybrid sound absorber, based on a combined approach for sound absorption. A flexible micro-perforated panel (MPP) is used as the passive sound absorber for mid and high frequencies and a piezoelectric patch as the active control actuator for low frequency. The volume of this new absorber is highly reduced compare to conventional hybrid systems which employ porous layer as passive part and loudspeaker as active part. The vibration effect of the MPP in the hybrid system is also considered. Theoretical and experimental results show that the flexible MPP has the potential to dissipate more energy and can be utilized to improve absorption performance of the hybrid system by appropriately selecting its parameters.

scholarly journals Acoustic Properties of Sound Absorber from Modified Polyester with Filler Sodium Bicarbonate

2018 ◽  
Vol 34 (4) ◽  
pp. 2187-2191
Author(s):  
Nasmi Herlina Sari ◽  
Jauhar Fajrin
Keyword(s):  
Absorption Coefficient ◽  
Sodium Bicarbonate ◽  
Acoustic Impedance ◽  
Sound Absorption ◽  
Polyester Resin ◽  
Acoustic Properties ◽  
Acoustic Parameters ◽  
Absorbent Material ◽  
Sound Absorber ◽  
Absorption Performance

The combination of low price, ease of manufacturing and waterproofing characteristics has placed polyester resin as a potential sound absorbent material. Previous studies showed that adding filler material to the blending may increase the acoustics properties of a sound absorbent material. This study aims to investigate the potential of sodium bicarbonate (NaHCO3) to be employed as a filler to improve the acoustic properties of the sound absorber made of polyester resin. Two important acoustic parameters were carefully assessed; absorption coefficient and acoustic impedance. The results showed that the sound absorption performance increased significantly at low and medium frequencies in the presence of NaHCO3 filler in polyester resin. Meanwhile, the use of a back cavity on the absorbent material reduced the sound absorption performance of materials at low and medium frequencies. This suggests that sound absorber made of polyester with sodium bicarbonate filler may be used as an alternative for sound absorber materials.

Sign in / Sign up

Export Citation Format

Share Document