SOUND DAMPING

NF Optimized for materials with high sound damping 0.01 to 10.5 MHz (-3 dB)... 

In testing materials with high sound damping, the burst transmitter increases the signal-to-noise ratio to, typically, 12 dB. Typical applications honeycomb and concrete components, and air-coupled testing. 

The HILL-SCAN 304INF board is optimized for low test frequencies so that materials with high sound damping such as concrete can be sueeessfully inspeeted by the echo technique. 

Dent resistance 7. Better strength-to- 4. Higher impact 7. Better sound damping 5. Better sound damping... 

Better sound damping 6. Lower shipping costs i. Inherent structural... 

Plumbing and installation sector small pressure vessels, sound-damping mountings for WCs and bathrooms, toilet cistern valves. .. 

All dynamic mechanical measurements employed a Rheo-vibron direct reading viscoelastometer> model DDV-II (Vi-bron, manufactured by the Toyo Measuring Instrument Co.j Ltd., Tokyo, Japan.) The temperature range employed was from -100°C to +100 C, with a heating rate of about 1 C° per minute. To better correlate with sound damping experiments conducted in our laboratory, a frequency of 110 Hz was employed. As per requirements of the instrLunent, the sample dimensions were of the order of 10 cm x 10 cm x 2 cm. 

Due to the high energy-absorbing abilities of viscoelastic foams, the foams are sometimes called energy-absorbing foams or sound-damping foams. However, die sound-absorption and impact-absorption properties are somewhat different. Therefore, optimum formulations for making them are not exactly the same. 

Biofibers can be effectively reinforced within the polymeric matrices in different ways to achieve desired properties such as strength, stiffness, low density, and sound damping, along with eco-friendly characteristics and texture in the composites. The use of biofibers for various commercial applications originated back in the 1990 s. Owing to low prices and the steadily rising performance of technical and standard plastics, the application of these fibers... 

Fewer parts required for 6. Better sound damping 4. Higher impact resistance 7. Better sound damping 4. Better large-part capability ... 

Better sound damping 8. Lower tooling costs 8. Inherent structural strength ... 

During recent years, there have been new developments in the area of spacer textiles ITV Denkendorf has developed a process in which two separated textile fabric layers, covered by transparent foils, are connected by a spacer fabric. Due to this specific construction, an air space is created which provides a high degree of heat and acoustic insulation. Spacer fabrics, laminated or coated with transparent foil on both sides, are increasingly used for transparent thermal insulation. Woven spacer fabrics can be produced up to 600 mm in width and are used, sometimes with filUng, for sound damping (Fig. 2.8). 

Polycarbonate (PC) foil is used for illumination in ceilings or walls. The thermoplastic PC has a transparency like that of glass, may be coloured and welded, is dimensionally stable, has a high impact resistance and may also be used for indoor sound-damping by making perforations in the foil. Like ETFE, polycarbonate is also flame retardant. 

PTFE-coated glass fabric with 10% translucency, 0.4 low-e, 70% sound damping capabilities. 

Tan 5 sometimes is referred to as internal friction or damping such as vibration or sound damping. It is the ratio of energy dissipated per cycle to the maximum potential energy stored dining a cycle. Tan 5 is also used to evaluate T of the samples (Lu et al. 2003). Figure 14 (c) dehneates the vibration of tan 5 of the control PU and FR-filled PU composites. 

Based on the acoustic equations, Millikan s formula for the drag of droplets and the transport matrix for heat and mass transfer between droplets and their surrounding vapour, a numerical solution for the sound attenuation is given and the influences of droplet size and the evaporation coefficient are discussed. A simplified relationship for the sound damping is suggested which reveals 3 typical relaxation times characterizing the dependence of sound attenuation on the sound frequency. 

This approximation is valid provided that the internal relaxation effects in the vapour have no marked influence on the sound damping. Based on an elementary consideration (Maxwell s method) we found for... 

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