Link between Acoustic and Hygrothermal Behavior of Hemp Shiv and Pith Composites

Bio-based materials are an environmentally friendly alternative to classic construction materials, yet their generally low density can lead to poor acoustic properties. The acoustic performance of hemp shiv and sunflower pith composites is therefore analyzed using Kundt’s tube. Although the loose aggregates present an exceptional sound absorbing behavior, it can be notably worsened in the presence of certain binders. The Transmission Loss is nevertheless enhanced by the binders, although it does not exceed 20 dB in most cases. For both properties, the type of binder has been found to be the most influential parameter. Through the Kundt’s tube method, it is also possible to determine the geometrical parameters of the composites’ microstructure, which have been observed to be similar for materials presenting comparable hygrothermal properties and containing the same binder. In a previous work, an experimental correlation was found between the thermal conductivity and the interparticle porosity of the aforementioned composites, which is compared to theoretical thermal conductivity models from literature without finding any apparent correspondence.

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Sound insulation performance of pyramidal truss core sandwich structure with frame

Journal of Sandwich Structures & Materials ◽

10.1177/10996362211028899 ◽

2021 ◽

pp. 109963622110288

Author(s):

Yu-Zhou Wang ◽

Li Ma

Keyword(s):

Mechanical Properties ◽

Sandwich Structure ◽

Transmission Loss ◽

Low Frequency ◽

Sound Insulation ◽

Geometrical Parameters ◽

Acoustic Performance ◽

Truss Core ◽

Pyramidal Truss ◽

Wave Angle

Recently, sandwich structures have been widely used in different fields because of their good mechanical properties, but these structures are weak in acoustic performance. In this paper, by combining pyramidal truss core sandwich structure with frame, a new structure is proposed with both good mechanical properties and excellent acoustic performance at low frequency. An analytical model of the pyramidal truss core sandwich structure with frame is developed to investigate the sound transmission loss (STL) performance. Finite element method (FEM) is also used to investigate the STL performance at low frequency. The effects of the incident wave angle and the geometrical parameters on the STL of the structure are discussed.

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Elaboration and Characterization of Composite Materials Based on Plaster-Gypsum and Mineral Additives for Energy Efficiency in Buildings

Proceedings ◽

10.3390/proceedings2019034022 ◽

2019 ◽

Vol 34 (1) ◽

pp. 22

Author(s):

Bouzit ◽

Taha

Keyword(s):

Thermal Conductivity ◽

Energy Efficiency ◽

Composite Materials ◽

Building Material ◽

Building Materials ◽

Building Envelope ◽

Acoustic Properties ◽

Building Sector ◽

Acoustic Performance ◽

Mineral Additives

The building sector is one of the largest energy consumers in the world, prompting scientific researchers to find solutions to the problem. The choice of appropriate building materials presents a considerable challenge for improving the thermal comfort of buildings. In this scenario, plaster-based insulating materials have more and more interests and new applications, such as insulating coatings developing the building envelope. Several works are being done to improve energy efficiency in the building sector through the study of building materials with insulation quality and energy savings. In this work, new composite materials, plaster-gypsum with mineral additives are produced and evaluated experimentally to obtain low-cost materials with improved thermo-physical and acoustic properties. The resulting composites are intended for use in building walls. Plaster-gypsum is presented as a high-performance thermal material, and mineral additives are of great importance because of their nature and are environmentally friendly. Measurements of thermal properties are carried and measurements of acoustic properties. The results show that it is possible to improve the thermal and acoustic performance of building material by using plaster as a base material and by incorporating thermal insulators. The thermal conductivity of plaster alone is greater than that of plaster with mineral additives, offer interesting thermal and acoustic performance. By varying the additives, the thermal conductivity changes. Finally, comparing the results, plaster with mineral additives is considered the best building material in this study

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Acoustic performance analysis of Helmholtz resonators with conical necks and its application

Noise Control Engineering Journal ◽

10.3397/1/376714 ◽

2019 ◽

Vol 67 (3) ◽

pp. 155-167 ◽

Cited By ~ 1

Author(s):

Haitao Liu

Keyword(s):

Finite Element ◽

Prediction Model ◽

Transmission Loss ◽

Low Frequency ◽

Wide Band ◽

Acoustic Properties ◽

Frequency Range ◽

Acoustic Attenuation ◽

Acoustic Performance ◽

Helmholtz Resonators

The acoustic properties of the Helmholtz resonators with conical necks, which have broad acoustic attenuation band performance in the low frequency range, are investigated in this study. In order to investigate its wide-band acoustic attenuation mechanism, three-dimensional finite element models for the Helmholtz resonators with different necks are built respectively. The acoustic performance prediction model based on the one-dimensional analytical approach with acoustic length corrections is built to calculate the transmission loss results more efficiently, and the formula for calculating the resonance frequency is also derived. Then, the prediction model and the formula are verified by finite element method and experiment, which show good agreements. As a result, the prediction model is applied to analyze the sound attenuation properties of the Helmholtz resonators with conical necks, and the results show that the acoustic attenuation bandwidth in the low frequency range is improved by increasing the taper angle of the neck. At last, the approaches for the Helmholtz resonators with conical necks are applied to design an actual middle silencer of a passenger car. The results show that the designed middle silencer performs much better than the original one, which can effectively eliminate the exhaust order noise to meet the standard of exhaust noise control. The test results fully reveal that the Helmholtz resonators with conical necks in the muffler can play a better role in eliminating exhaust order noise, and the approaches proposed in this article can effectively guide the design of Helmholtz resonators with conical necks.

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Helmholtz Resonator with Extended Neck and Absorbing Material

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.141.308 ◽

2011 ◽

Vol 141 ◽

pp. 308-312 ◽

Cited By ~ 2

Author(s):

Rong Bi ◽

Zheng Shi Liu ◽

Kai Ming Li ◽

Jun Chen ◽

Yong Wang

Keyword(s):

Transmission Loss ◽

Helmholtz Resonator ◽

Acoustic Properties ◽

Mode Matching ◽

Acoustic Attenuation ◽

Matching Method ◽

Acoustic Performance ◽

Absorbing Materials ◽

Absorbing Material ◽

Method Show

The acoustic attenuation of Helmholtz resonator including an extended neck and sound–absorbing materials is investigated in current study. A two-dimensional analytical method based on mode matching method is developed to determine the Transmission loss (TL) of a piston-driven model of Helmholtz resonator. The resonance frequency and Transmission loss predicted from this method show reasonable agreements with published experimental results. Finally, this method is used to examine the effect of length of extended neck, extended neck with/without absorbing material and acoustic properties of sound-absorbing material on acoustic performance of Helmholtz resonator.

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Sound-Absorbing Acoustic Concretes: A Review

Sustainability ◽

10.3390/su131910712 ◽

2021 ◽

Vol 13 (19) ◽

pp. 10712 ◽

Cited By ~ 1

Author(s):

Mugahed Amran ◽

Roman Fediuk ◽

Gunasekaran Murali ◽

Nikolai Vatin ◽

Amin Al-Fakih

Keyword(s):

Building Materials ◽

Measurement Techniques ◽

Construction Materials ◽

Residential Building ◽

Well Being ◽

Acoustic Properties ◽

Sound Insulation ◽

Absorption Properties ◽

Acoustic Performance ◽

Cellular Concrete

Noise is continuously treated as an annoyance to humans and indeed commotion contamination shows up within the environment, causing inconvenience. This is likewise interesting to the engineering tactic that inclines to develop this noise proliferation. The basics of the sound-retaining proliferation, sound-absorbing properties, and its variables were rarely considered by previous researchers. Thus, the acoustic performance and sound insulation of constructions have gained significance over the last five decades due to the trend for accommodating inner-city flat and multi-story residential building condominiums. Due to this dilemma, the proliferation of high-driven entertaining schemes has engaged extraordinary demands on building for its acoustic performance. Yet, construction industries worldwide have started to mainly use sound-absorbing concrete to reduce the frequency of sounds in opened-and-closed areas and increase sound insulation. As reported, the concrete acoustic properties generally rely on its density, exhibiting that the lighter ones, such as cellular concrete, will absorb more sound than high-density concretes. However, this paper has an objective to afford a wide-ranging review of sound-absorbing acoustic concretes, including the measurement techniques and insulation characteristics of building materials and the sound absorption properties of construction materials. It is also intended to extensively review to provide insights into the possible use of a typical sound-absorbing acoustic concrete in today’s building industry to enhance housing occupants’ efficiency, comfort, well-being, and safety.

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Tuning acoustic performance of multi-chamber hybrid mufflers

Vietnam Journal of Mechanics ◽

10.15625/0866-7136/14904 ◽

2021 ◽

Author(s):

Van-Hai Trinh

Keyword(s):

Transmission Loss ◽

Sound Transmission ◽

Numerical Approach ◽

Geometrical Parameters ◽

Sound Transmission Loss ◽

Expansion Chamber ◽

Low Frequencies ◽

Acoustic Performance ◽

Chamber Length ◽

Perforated Tube

In this paper, we investigate the functional acoustic performance of multi-chamber mufflers using a numerical approach. The wave propagation governing in expansion chamber domains is first introduced and solved by the finite element method. Our numerical results of selected muffler configurations are compared with the reference predictions model and experiments in order to validate the present procedure. Then, the influence of the geometry characteristics of typical and hybrid configurations of multi-chambered mufflers (number of sub-chambers, micro-perforated tube structure) on their sound transmission loss is studied. The obtained results indicate that the structure of the considered muffler has a strong effect on their acoustical performance, and the location and the high level of resonances of the sound transmission loss behavior are strongly related to the number of sub-chambers as well as micro-perforated tube characteristics. By tuning geometrical parameters (e.g., having a small perforation ratio), we enable to design mufflers having a higher sound transmission loss (up to 110 dB) at low frequencies (~ 195 Hz) but a constraint space (e.g., acoustic chamber length of 300 mm).

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Industrial bio-based plant aggregates as hygric and insulating construction materials for energy efficient building

Frontiers of Chemical Science and Engineering ◽

10.1007/s11705-020-1960-7 ◽

2020 ◽

Author(s):

Yunhong Jiang ◽

Mike Lawrence ◽

Meng Zhang ◽

Jiandong Cui

Keyword(s):

Thermal Conductivity ◽

Bulk Density ◽

Wheat Straw ◽

Construction Materials ◽

Raw Material ◽

High Porosity ◽

Buffer Value ◽

Hemp Shiv ◽

Energy Efficient Building ◽

Highly Porous

Abstract In this paper, the bulk density, microstructure, porosity and pore size distribution of the selected aggregates, including hemp shiv, flax shiv, rape shiv and wheat straw, are fully studied due to these properties are highly related to their excellent characteristics and more or less linked to the properties of the final product. The scanning electron microscope results showed all the selected aggregates have a highly porous and complex hierarchical structure, whereas the arrangement of pores and the thickness of cell wall are significantly different among these aggregates. All the selected aggregates had a low bulk density ranging from 30 to 130 kg · m−3 and a high porosity between 75.81% and 88.74%. The thermal conductivity of the selected bio-aggregates ranged from 0.04 to 0.06 W·m−1·K−1. The thermal conductivity of the selected aggregates was not only depending on the bulk density of the sample but also depending on the raw material. Hemp shiv, rape shiv and flax shiv were excellent hygric regulators with moisture buffer value (MBV) ranging from 2.07 to 2.36 g·m−2·%RH−1, whereas, wheat straw had a lower MBV value ranging from 1.76 to 1.97 g·m−2·%RH−1. The results showed that particle size does not affect the MBV value. The MBV value increases linearly with bulk density.

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Synthesis and Acoustic Study of a New Tung Oil-Based Polyurethane Composite Foam with the Addition of Miscanthus Lutarioriparius

Polymers ◽

10.3390/polym11071144 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1144 ◽

Cited By ~ 1

Author(s):

Yangjie Ji ◽

Shuming Chen ◽

Yabing Cheng

Keyword(s):

Mechanical Properties ◽

Polyurethane Foam ◽

Transmission Loss ◽

Polyurethane Foams ◽

Acoustic Properties ◽

Composite Foam ◽

Tung Oil ◽

Acoustic Performance ◽

Miscanthus Lutarioriparius ◽

Polyurethane Composite

Polyurethane foam is commonly used in the automobile industry due to its favorable acoustic performances. In this study, a new tung oil-based polyurethane composite foam (TOPUF) was prepared by a one-step method. Different forms and contents of miscanthus lutarioriparius (ML) were used in TOPUF for improving acoustic performance. Polyurethane foams were characterized by means of Fourier transform infrared and SEM. The acoustic properties and mechanical properties of TOPUF, obtained with ML, were determined and compared with pure petroleum-based polyurethane foam. The results illustrate that the modification of TOPUF with the ML has a positive effect on the acoustic and mechanical properties in comparison to the unmodified foam. TOPUF obtained with ML powders has better acoustic performance than that obtained with ML strips. The optimum acoustic performance is achieved at the filler content of 0.3 wt%. The average sound absorption coefficient and transmission loss can reach 0.518, and 19.05 dB, respectively.

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Investigation of Thermal, Mechanical and Acoustic Performance of Bio-Materials Based on Plaster-Gypsum and Cork

10.4028/www.scientific.net/cta.1.685 ◽

2022 ◽

Author(s):

Said Bouzit ◽

Francesca Merli ◽

Mohammed Sonebi ◽

Sofiane Amziane ◽

Cinzia Buratti ◽

...

Keyword(s):

Building Materials ◽

Transmission Loss ◽

Energy Performance ◽

Building Envelope ◽

Acoustic Properties ◽

Acoustic Performance ◽

Energy Performance Of Buildings ◽

New Applications ◽

Alternative Solutions ◽

Selection Of

The building sector is one of the biggest consumers of energy in the world and it is pushing the scientific community to find various alternative solutions to solve the problem of thermal insulation of buildings. Therefore, the selection of appropriate building materials is a major challenge for improving the thermal comfort and energy performance of buildings. In this scenario, the interest of plaster-based composites as insulating materials increases, in particular for new applications, as insulators for the building envelope, and this deserves to be studied. In this investigation, new plaster-based composites with cork were produced and tested at lab scale, in order to obtain cheap solutions with improved thermo-physical and acoustic performance. The results show that it is possible to improve the thermal, mechanical, and acoustic performance of construction biomaterials by using plaster as a binder and cork as a natural reinforcement: thermal conductivity was equal to 0.097 W/m.K, the compressive strength to about 2.30 MPa, and the transmission loss to about 40 dB. Keywords: Plaster-Gypsum; Cork; Thermal, Mechanical and Acoustic Properties.

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Optimization of Sound Transmission Loss Characteristics of Orthogonally Stiffened Plate

Journal of Theoretical and Computational Acoustics ◽

10.1142/s259172851850010x ◽

2018 ◽

Vol 26 (04) ◽

pp. 1850010 ◽

Cited By ~ 1

Author(s):

Tao Fu ◽

Zhaobo Chen ◽

Hongyin Yu ◽

Chengfei Li ◽

Xiaoxiang Liu

Keyword(s):

Transmission Loss ◽

Structural Parameters ◽

Sound Transmission ◽

Stiffened Plates ◽

Geometrical Parameters ◽

Sound Transmission Loss ◽

Stiffened Plate ◽

Acoustic Performance ◽

Theoretical Predictions ◽

Field Excitation

An analytical model is developed to investigate the sound transmission loss from orthogonally rib-stiffened plate structure under diffuse acoustic field excitation. The validity and feasibility of the model are verified by comparing the present theoretical predictions with the numerical results published previously. The influences of structure geometrical parameters on sound transmission loss are subsequently presented. The optimization algorithm is used to search for the optimal structural parameters with the objective to maximize the sound transmission loss over a frequency band. Furthermore, the sensitivity of structural parameters on the overall vibration and acoustic performance of the stiffened plates structure is also analyzed.

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