Optimization of structural parameters for the sound absorption performance of a cellular ceramic foam

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
J.X. Sun ◽  
P.S. Liu
Keyword(s):  
Pore Size ◽  
Sound Absorption ◽  
Orthogonal Experiment ◽  
Structural Parameters ◽  
Sample Thickness ◽  
Ceramic Foam ◽  
Content Type ◽  
Absorption Performance ◽  
Main Factor ◽  
Cellular Ceramic

PurposeThe purpose of this paper is to provide an optimization schedule of structural parameters for the sound absorption performance of a cellular ceramic foam in the sound frequency range of 200–4,000 Hz.Design/methodology/approachThe cellular ceramic foam with porosity of about 60–75% and the pore size of about 1–7 mm was successfully prepared by using natural zeolite powder as the main raw material. For this ceramic foam, the sound absorption performance was measured, and the absorption structure was optimized by some important structural parameters. With orthogonal experiment, optimization of structural parameters was found for absorption performance. By means of the range analysis method, the main factor is known to influence the performance of ceramic foam.FindingsThe present ceramic foam may have good absorption performance although at relatively low frequencies of 400–4,000 Hz while structural parameters of sample are appropriately combined. With orthogonal experiment, optimization of structural parameters for the absorption performance was found to be as follows: sample thickness, 25 mm; porosity, 73.5%; pore size, 4–5 mm and air gap depth, 20 mm. To influence the performance, sample thickness is the main factor, air gap depth is the second and both of pore size and porosity would have a relatively slight effect.Originality/valueThis paper presents a method to optimize the structural parameters of a cellular ceramic foam for sound absorption performance by means of orthogonal experiment.

Theoretical and numerical study of nonlinear acoustic absorbers for low frequency noise control

2021 ◽  
Vol 263 (1) ◽  
pp. 5600-5604
Author(s):  
Min Yang ◽  
Xianhui Li ◽  
Zenong Cai ◽  
Junjuan Zhao ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Averaging Method ◽  
Numerical Study ◽  
Structural Parameters ◽  
Low Frequency ◽  
Frequency Noise ◽  
Flow Equations ◽  
State Response ◽  
Runge Kutta Method ◽  
Absorption Performance

In this paper, the sound absorption characteristics of cubic nonlinear sound-absorbing structures are analyzed by theoretical and numerical methods. The slow flow equations of the system are derived by using complexification averaging method, and the nonlinear equations which describe the steady- state response are obtained. The resulting equations are verified by comparing the results which respectively obtained from complexification-averaging method and Runge-Kutta method. It is helpful to optimize the structural parameters and further improve the sound absorption performance to study the variation of the sound absorption performance of cubic nonlinear structure with its structural parameters.

Ultralight micro-perforated sandwich panel with hierarchical honeycomb core for sound absorption

2021 ◽  
pp. 109963622199388
Author(s):  
Wei He ◽  
Xiangjun Peng ◽  
Fengxian Xin ◽  
Tian Jian Lu
Keyword(s):  
Theoretical Model ◽  
Sound Absorption ◽  
Sandwich Panel ◽  
Structural Parameters ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Physical Mechanisms ◽  
Wide Range ◽  
Model Predictions ◽  
Absorption Performance

A theoretical model is developed to study the superior sound absorption performance of ultralight mirco-perforated sandwich panels with double-layer hierarchical honeycomb core. Numerical simulations are performed to validate theoretical model predictions and explore physical mechanisms underlying the sound absorption. Systematic parametric study is implemented to investigate the influence of specific structural parameters on sound absorption. To maximize sound absorption, optimal structural parameters of the hierarchical sandwich are obtained using the method of simulated annealing. It is demonstrated that viscous dissipation of the air inside micro-perforations and around inlet/outlet regions dominates sound absorption. Compared to micro-perforated sandwich panels with regular honeycomb core, not only the proposed hierarchical construction has much improved load-bearing capacity, but also significantly enhanced sound absorption covers a wide range of frequency.

scholarly journals Parameter Optimization for Composite Structures of Microperforated Panel and Porous Metal for Optimal Sound Absorption Performance

2019 ◽  
Vol 9 (22) ◽  
pp. 4798 ◽  
Author(s):  
Haiqin Duan ◽  
Xinmin Shen ◽  
Fei Yang ◽  
Panfeng Bai ◽  
Xiaofang Lou ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Parameter Optimization ◽  
Composite Structure ◽  
Composite Structures ◽  
Sound Absorption ◽  
Structural Parameters ◽  
Porous Metal ◽  
Total Thickness ◽  
Frequency Range ◽  
Absorption Performance

The composite structure of a microperforated panel and porous metal is a promising sound absorber for industrial noise reduction, sound absorption performance of which can be improved through parameter optimization. A theoretical model is constructed for the composite structure of a microperforated panel and porous metal based on Maa’s theory and the Johnson–Champoux–Allard model. When the limited total thickness is 30 mm, 50 mm, and 100 mm respectively, dimensional optimization of structural parameters of the proposed composite structure is conducted for the optimal average sound absorption coefficient in the frequency range (2000 Hz, 6000 Hz) through a cuckoo search algorithm. Simulation models of the composite structures with optimal structural parameters are constructed based on the finite element method. Validations of the optimal composite structures are conducted based on the standing wave tube method. Comparative analysis of the theoretical data, simulation data, and experimental data validates feasibility and effectiveness of the parameter optimization. The optimal sandwich structure with an actual total thickness of 36.8 mm can obtain the average sound absorption coefficient of 97.65% in the frequency range (2000 Hz, 6000 Hz), which is favorable to promote practical application of the composite structures in the fields of sound absorption and noise reduction.

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.

The Influence of Structural Parameters on the Sound Absorption Performance of Micro Perforated Absorber

2014 ◽  
Vol 701-702 ◽  
pp. 424-427
Author(s):  
Meng Zi Sun ◽  
Fei Huang ◽  
Hua Jing Li
Keyword(s):  
Numerical Simulation ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Structural Parameters ◽  
Experimental Result ◽  
Laser Machining ◽  
Parameter Combination ◽  
Absorption Performance ◽  
High Absorption Coefficient ◽  
High Absorption

The sound absorption performance of MPA (micro perforated absorber) mainly depends on its structural parameters. Reasonable parameter combination will get a high absorption coefficient. In this paper numerical simulation was used to study sound absorption performance. By this means, the influence of the different parameters on the sound absorption performance are discovered. To verify the result of numerical simulation, MPA samples are fabricated using optimized parameters by laser machining method. The sound absorption performances of these samples are tested and the experimental result is consistent with that of numerical simulation.

Sound absorption performance of a lightweight ceramic foam

2020 ◽  
Vol 46 (14) ◽  
pp. 22699-22708
Author(s):  
J.H. Chen ◽  
P.S. Liu ◽  
J.X. Sun
Keyword(s):  
Sound Absorption ◽  
Ceramic Foam ◽  
Absorption Performance

Acoustic evaluation of Struto nonwovens and their relationship with thermal properties

2016 ◽  
Vol 88 (4) ◽  
pp. 426-437 ◽  
Author(s):  
Tao Yang ◽  
Xiaoman Xiong ◽  
Rajesh Mishra ◽  
Jan Novák ◽  
Jiří Militký
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Resistance ◽  
Strong Correlation ◽  
Sound Absorption ◽  
Structural Parameters ◽  
Airflow Resistance ◽  
Nonwoven Fabrics ◽  
Acoustic Evaluation ◽  
Absorption Performance

This paper presents an experimental investigation on the sound absorption behavior and thermal properties of Struto nonwovens by establishing relationship between these properties. Seven Struto nonwoven fabrics were selected to examine the noise reduction coefficient (NRC) and average values of sound absorption coefficients ([Formula: see text]) as well as thermal properties, including thermal conductivity and thermal resistance. The Brüel and Kjær impedance tube instrument and Alambeta were used for the evaluation of acoustic and thermal properties, respectively. The influence of structural parameters on acoustic and thermal properties of Struto nonwovens were investigated and analyzed. The results showed that Struto nonwovens with higher thickness, finer fibers and higher fabric grams per square meter can provide better sound absorption performance. The effect of specific airflow resistance on sound absorption performance was also investigated. It is observed that sound absorption performance has a strong correlation with specific airflow resistance. The effect of porosity on specific airflow resistance and thermal properties was studied in detail. The result indicated that porosity has a strong correlation with specific airflow resistance and thermal properties. It was also observed that sound absorption, the NRC and [Formula: see text] have an insignificant correlation with thermal conductivity, while they are strongly correlated with thermal resistance. The correlation coefficient of the NRC with thermal resistance is 0.9835, indicating that the NRC is directly proportional to the thermal resistance of Struto nonwovens.

Sound absorption performance of flexible polyurethane/silicon dioxide perforated coating composites

2021 ◽  
pp. 004051752110155
Author(s):  
Min Peng ◽  
Xiaoming Zhao ◽  
Weibin Li
Keyword(s):  
Silicon Dioxide ◽  
Sound Absorption ◽  
Woven Fabric ◽  
Perforation Rate ◽  
Cavity Depth ◽  
Resonant Frequencies ◽  
The Matrix ◽  
Absorption Performance ◽  
Traditional Sense ◽  
Flexible Polyurethane

Perforated materials in the traditional sense are rigid, usually dense, costly and inflexible. For this study, polyester/cotton blended woven fabric as the base fabric, nano-SiO2 (silicon dioxide) as the functional particles and PU (polyurethane) as the matrix were selected. Accordingly, flexible PU/SiO2 perforated coating composites with different process parameters were developed. The influence of the nano-SiO2 content, perforation diameter, perforation rate, number of fiber felt layers and cavity depth on the sound absorption coefficient were investigated. The resonant frequencies of materials with different cavity depths were evaluated by both theoretical calculation and experimental method. It was found that the flexible perforated composite has good sound absorption and mechanical properties, and has great potential for applications requiring soft and lightweight sound absorption materials.

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

Human rights of people with mental illness diagnosis: perceptions among service users, family members and health professionals in Tunisia

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mayssa Rekhis ◽  
Sami Ouanes ◽  
Abir Ben Hamouda ◽  
Rym Rafrafi
Keyword(s):  
Mental Illness ◽  
Human Rights ◽  
Family Members ◽  
Mental Illnesses ◽  
Service Users ◽  
Content Type ◽  
People With Mental Illness ◽  
The Family ◽  
The Right ◽  
Main Factor

Purpose This study aims to assess the awareness about the rights of people with mental illness in the main psychiatric hospital in Tunisia among the service users, the family members and the staff. Design/methodology/approach The Convention of Rights of People with Disabilities mandates that State Parties initiate and maintain campaigns and human rights training to promote understanding of the rights of people with mental illnesses, considered as a main factor for their fulfillment. Service users, family members and staff evaluated, through a survey, the importance of ten rights for persons with mental illness, stated in the convention. Findings Disparities were found in the perception of the different rights by and between the three groups. The highest levels of awareness were associated with the freedom from torture or degrading treatment and the right to live with dignity and respect, whereas the lower importance were assigned to the right to participation in recovery plans, to give consent and to exercise legal capacity. Originality/value The lack of awareness and the poor perception of rights of people with mental illness is one of the barriers to their achievement. More training and awareness raising is necessary.

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