The Effect of Stitch Length on Sound Absorption Behaviour of Cone Knitted Structures.

Abstract

Acoustic materials play a crucial role in controlling sound in various environments, from industrial spaces to residential and public buildings. As concerns over noise pollution and the demand for energy-efficient, sound-controlling materials rise, there is growing interest in developing materials that offer superior sound absorption properties. Though textile structures are more popular for sound absorption applications, analysis of acoustic properties of 3D knitted structures is not substantiated by much research. 3D knitted fabrics offer distinct advantages due to their increased surface area, which enhances sound wave interaction and absorption. Their unique geometry and customizable parameters enable precise control over their physical properties, including porosity, surface area, and density. These features allow for enhanced interaction with sound waves, improving their absorption performance across different frequencies. Therefore, this study investigates the effect of stitch length on sound absorption behavior of cone knitted structures using the reverberation room method. Four samples with stitch lengths of 3.72 mm, 3.04 mm, 2.61 mm, and 2.08 mm were prepared using a flatbed knitting machine and tested according to the ASTM C423 standard. This range of stitch lengths was selected by adjusting the cam settings to prevent yarn or fabric damage. Reverberation time measurements across frequencies from 200 Hz to 10,000 Hz were conducted and sound absorption coefficients were derived using Sabine’s formula. Results indicate that shorter stitch lengths, associated with higher stitch and surface densities, enhance sound absorption, particularly at higher frequencies. These findings suggest that 3D knitted cone fabrics are effective in sound absorption, with potential applications in building acoustics and noise control. Optimizing fabric geometry and structural parameters can enable the development of versatile and efficient acoustic materials, contributing to sustainable solutions for noise pollution and energy-efficient building design.