Experimental Study on the Sound-Absorption Capability of Nonwoven Sound-Absorbing Material under Different Density Combination

2011 ◽  
Vol 332-334 ◽  
pp. 1304-1307
Author(s):  
Wen Su ◽  
Xiao Ming Qian ◽  
Xin Yu Li ◽  
Shu Sen Liu
Keyword(s):  
Experimental Study ◽  
Sound Absorption ◽  
Low Density ◽  
Surface Material ◽  
Nonwoven Materials ◽  
Absorbing Material

In this paper, the influence of different combination of different density of nonwoven materials on the sound-absorption capability is studied through the serial experiments. The results show that the structure with low density on the surface material and dense density in the middle of the material will have better capacity in absorbing sound.

Influence of Thickness and Density of Nonwoven Sound-Absorbing Material on the Sound-Absorption Capability

2011 ◽  
Vol 197-198 ◽  
pp. 440-443 ◽  
Author(s):  
Wen Su ◽  
Xiao Ming Qian ◽  
Xin Yu Li ◽  
Shu Sen Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Low Density ◽  
Density Structure ◽  
High Frequencies ◽  
Material Thickness ◽  
Nonwoven Materials ◽  
Absorbing Material

In this paper, the influence of thickness and density of nonwoven materials on the sound-absorption capability is studied through the serial experiments. The results show that the sound-absorption coefficient increases with material thickness increasing and this relationship is more distinct for low or mid frequencies than for high frequencies. When the material thickness is made constant, the sound-absorption coefficient increases with density increasing for low-mid frequencies, while the coefficient decreases with density for high frequencies. The conclusion is that the nonwoven materials with low density structure own better capacity in absorbing sound according to the experiment results.

Fabrication of Ultra Low-Density Binderless Sandwiching Materials by Rapid Steam Injection

2016 ◽  
Vol 852 ◽  
pp. 1482-1487
Author(s):  
Fan Cheng ◽  
Yu Hao Jiang ◽  
Jin Bo Chen ◽  
Peng Bo Lu ◽  
Ling Feng Su ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Sound Absorption ◽  
Building Materials ◽  
Bending Strength ◽  
Injection Pressure ◽  
Steam Injection ◽  
Low Density ◽  
Absorption Property ◽  
Injection Process ◽  
Injection Technology

Eco-friendly building materials with perfect thermal insulation & sound absorption property have become intriguing and eye-catching in recent years. In this work, the ultra low-density binderless sandwiching materials were firstly fabricated with ultra low-density of 60-80 kg/m3 by self-designed rapid steam injection technology. The main experimental factor of density, holding time, transmission time, steam injection pressure and fiber’s dimension was respectively investigated to their effects on formation of the new building materials. IR, Py GC-MS and AFM analysis were performed to study the mechanism of binderless sandwiching materials under steam injection process. The bending strength, thermal insulation & sound absorption property of the new materials were also studied. This new building material with no resin use and no formaldehyde release is expected to be reserved as the sandwich for designing thermal insulation & noise reduction building materials.

Double Perforated Honeycomb Panel as a Low Frequency Acoustic Absorber

1997 ◽  
Vol 4 (1) ◽  
pp. 21-37
Author(s):  
C.F. Ng ◽  
Qin Hao-Ming
Keyword(s):  
Experimental Study ◽  
Sound Absorption ◽  
Low Frequency ◽  
Air Gap ◽  
Light Weight ◽  
Frequency Sound ◽  
Honeycomb Sandwich ◽  
Perforated Sheets ◽  
Absorption Characteristics ◽  
Honeycomb Panel

This report deals with a theoretical and experimental study of the low frequency sound absorption characteristics of perforated honeycomb sandwich panels. The derivations of formulae for absorption in terms of double perforation ratio and air gap are presented. Results show that the honeycomb absorber, with double perforated sheets, can be an effective low frequency absorber for frequencies down to 63 Hz. In addition, honeycomb panels have advantages over other low frequency absorbers in that they are light weight and strong.

Ultrasonic-Vibration-Assisted Pelleting of Cellulosic Biomass: Effects of Moisture Content

2010 ◽  
Author(s):  
Xiaoxu Song ◽  
Meng Zhang ◽  
Z. J. Pei ◽  
Timothy Deines
Keyword(s):  
Experimental Study ◽  
Moisture Content ◽  
Ultrasonic Vibration ◽  
Transportation Cost ◽  
Cost Effective ◽  
Cellulosic Biomass ◽  
Low Density ◽  
High Transportation Cost ◽  
Biomass Materials ◽  
Pellet Density

Cellulosic biomass is an important source for making biofuels. However, there are several barriers to cost-effective manufacturing of biofuels using cellulosic biomass. One such barrier is related to the high transportation cost due to the low density of cellulosic biomass. Pelleting of cellulosic biomass is one way to increase its density. This paper reports an experimental study on ultrasonic vibration-assisted pelleting of cellulosic biomass. The study was focused on the effects of moisture content (MC) on pellet density of three kinds of cellulosic biomass (wheat straw, switchgrass, and sorghum). The experimental results show that sorghum has the highest density with three levels of MC among these biomass materials. The highest density was found with sorghum of 20% MC.

Surface pressures and their corrections for the flow past a finite-length plate in supersonic low density flow

1979 ◽  
Vol 95 (1) ◽  
pp. 177-187 ◽  
Author(s):  
S. L. Gai
Keyword(s):  
Experimental Study ◽  
Finite Length ◽  
Leading Edge ◽  
Low Density ◽  
Cold Wall ◽  
Trailing Edge ◽  
Flow Past ◽  
Density Flow ◽  
Recent Method

An experimental study of the flow past a thin finite length plate in a supersonic low density stream is reported. The paper discusses the corrections that are necessary for surface pressures measured under rarefied conditions. It is shown that the recent method of ‘orifice’ corrections due to Harbour & Bienkowski is versatile and reliable to use for both cold wall and insulated wall measurements. For the conditions of the experiment, the flow over the plate was found to be dominated by both leading-edge and trailing-edge interactions.

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