2.2 Technical solution

The acoustic element in this case is placed onto a frame—in the form of a regular grid of glass tapes of a negligible thickness—the back side which is covered by a thin carrier layer with a nanofibrous membrane. The design is based on the solution of a general element, placed onto a frame in the form of linear structures with a nanofibrous layer (Figure 1), where the grid provides regular open areas with a given size and shape of the holes and their spacing. Figure 2 compares the sound absorbing properties of an acoustic element with and without a nanofibrous membrane. The proposed element is then compared with commonly used absorbent material with the best sound absorption results that have been measured (Figure 3). From this comparison, it is clear that the developed acoustic element can compete with the material that is available on the market with the best results, even at a lower composite element thickness (also assumed with a possible air gap). Compared nanofibrous composite thicknesses are 30, 40, 50, and 60 mm of foam material. The benefits of the proposed technology are the space between the acoustic element of thickness 1–5 mm and the wall/ceiling, which can be used to install lighting, speakers, etc.

designed for acrylic plasters. This white grid fabric has a basis weight of 145 g m<sup>2</sup> according to the producer, and the mesh spacing has a nominal size of 4.5 3.5 mm

Frequency dependence of the sound absorption coefficient; comparison of nanofibrous membrane of 0.2 gsm on a carrier of 25 gsm covering the grid of 4 4.5 mm mesh size with a thickness of 1 mm with different air gaps (30 mm, green; 40 mm, blue; 50 mm, red) and FOAM 60—foam rectangles with a thickness of 60 mm; width of the base of the rectangle 50 mm foot of the rectangle 40 mm, and top rectangle 60 mm (black). Took from

Frequency dependence of the sound absorption coefficient; comparison of nanofibrous membrane of 0.2 gsm on a carrier of 25 gsm covering the grid of 4 4.5 mm mesh size with a thickness of 1 mm with 50 mm air gap (red) and single carrier of 25 gsm covering the same grid of 4 4.5 mm mesh size with a thickness of 1 mm with

Sound Absorbing Resonator Based on the Framed Nanofibrous Membrane

DOI: http://dx.doi.org/10.5772/intechopen.82615

The smallest mesh size was given by the original dimensions of the grid. The smallest mesh size was determined at 4.1 4.3 mm (0.11 0.09 mm) and denoted 1G. The nearest bigger mesh denoted 2G was formed by cutting the weft yarn between two basic meshes at 9.4 4.1 mm (0.11 0.11 mm). Another bigger mesh denoted 3G was created by cutting the weft and warp threads between the four basic meshes at 9.0 9.4 mm (0.12 0.11 mm). The largest mesh denoted 4G was then formed by cutting out two weft and one warp yarn between the six basic meshes to a size of 9.0 14.2 mm ( 0.12 0.05 mm) (see Figure 4).

and a thickness of 0.47 mm.

Figure 3.

Figure 2.

50 mm air gap (black). Took from [21].

[21].

27

### 2.3 Experimental

#### 2.3.1 Grid design

The basis for the production of a mesh with different mesh size was the R117 A01 structural reinforcing fabric, manufactured by Saint-Gobain Adfors and

Sound Absorbing Resonator Based on the Framed Nanofibrous Membrane DOI: http://dx.doi.org/10.5772/intechopen.82615

#### Figure 2.

membrane, and, in general, the individual frame structure does not need to be repeated over the whole surface, and the element thus consists of many different borders that allow vibration of the membrane resulting in the unique properties of

the blue one is nanofibrous resonant membrane, and the red one is adhesive.

The principle of designing the final solution of a frame-based acoustic element in the form of linear formations with a nanofibrous layer in view and cut. The gray color in cross section shows the frame (wire construction),

The acoustic element in this case is placed onto a frame—in the form of a regular grid of glass tapes of a negligible thickness—the back side which is covered by a thin carrier layer with a nanofibrous membrane. The design is based on the solution of a

The basis for the production of a mesh with different mesh size was the R117 A01 structural reinforcing fabric, manufactured by Saint-Gobain Adfors and

general element, placed onto a frame in the form of linear structures with a nanofibrous layer (Figure 1), where the grid provides regular open areas with a given size and shape of the holes and their spacing. Figure 2 compares the sound absorbing properties of an acoustic element with and without a nanofibrous membrane. The proposed element is then compared with commonly used absorbent material with the best sound absorption results that have been measured (Figure 3). From this comparison, it is clear that the developed acoustic element can compete with the material that is available on the market with the best results, even at a lower composite element thickness (also assumed with a possible air gap). Compared nanofibrous composite thicknesses are 30, 40, 50, and 60 mm of foam material. The benefits of the proposed technology are the space between the acoustic element of thickness 1–5 mm and the wall/ceiling, which can be used to install

each oscillating surface.

Figure 1.

Acoustics of Materials

2.2 Technical solution

lighting, speakers, etc.

2.3 Experimental

2.3.1 Grid design

26

Frequency dependence of the sound absorption coefficient; comparison of nanofibrous membrane of 0.2 gsm on a carrier of 25 gsm covering the grid of 4 4.5 mm mesh size with a thickness of 1 mm with 50 mm air gap (red) and single carrier of 25 gsm covering the same grid of 4 4.5 mm mesh size with a thickness of 1 mm with 50 mm air gap (black). Took from [21].

#### Figure 3.

Frequency dependence of the sound absorption coefficient; comparison of nanofibrous membrane of 0.2 gsm on a carrier of 25 gsm covering the grid of 4 4.5 mm mesh size with a thickness of 1 mm with different air gaps (30 mm, green; 40 mm, blue; 50 mm, red) and FOAM 60—foam rectangles with a thickness of 60 mm; width of the base of the rectangle 50 mm foot of the rectangle 40 mm, and top rectangle 60 mm (black). Took from [21].

designed for acrylic plasters. This white grid fabric has a basis weight of 145 g m<sup>2</sup> according to the producer, and the mesh spacing has a nominal size of 4.5 3.5 mm and a thickness of 0.47 mm.

The smallest mesh size was given by the original dimensions of the grid. The smallest mesh size was determined at 4.1 4.3 mm (0.11 0.09 mm) and denoted 1G. The nearest bigger mesh denoted 2G was formed by cutting the weft yarn between two basic meshes at 9.4 4.1 mm (0.11 0.11 mm). Another bigger mesh denoted 3G was created by cutting the weft and warp threads between the four basic meshes at 9.0 9.4 mm (0.12 0.11 mm). The largest mesh denoted 4G was then formed by cutting out two weft and one warp yarn between the six basic meshes to a size of 9.0 14.2 mm ( 0.12 0.05 mm) (see Figure 4).

Figure 4. Photo of applied grids. Rectangle with different side dimensions: 4.1 4.3 mm; 9.4 4.1 mm; 9.0 9.4 mm; 9.0 14.2 mm.
