| With the rapid development of industrialization and urbanization in our country,noise pollution has become one of the four environmental pollution that endangers people’s health.At present,controlling the noise source and blocking the noise propagation path are the two main solutions.However,due to the complexity of the noise formation,it is difficult to reduce the noise at the sound source.Therefore,the sound wave energy is usually absorbed by the barrier to achieve the noise reduction effect.Among many sound absorbing materials,textile materials with loose porous structure have attracted wide attention.Knitted fabric,as a kind of textile structure constructed by loops,has the characteristics of loose,porous and large tensile deformation ability.When the sound wave enters the gap between the loops of knitted fabric,it will cause the air between the fibers and yarns and the material itself to vibrate.Friction between the air and the fiber material forms viscous resistance,which makes the sound energy converted into heat energy and attenuated.In addition,the complex structure formed by the knitting loops allows sound waves to be reflected back and forth,enhancing the dissipation of sound energy within the fabric.However,due to the large structural gap of common knitted fabrics,the sound absorption performance is weakened,and the propagation mechanism of sound wave in different knitted structures is not clear,which limits the further development of the knitted-structure sound absorbers.Therefore,Chenille yarn and polyester monofilament were selected as raw materials to prepare composite yarn with different braiding structures through 2D spindle braiding technology.Then,based on weft knitting technology,two kinds of rib-type knitted sound absorbers were designed,and their basic properties,porosity and sound absorbing performance were tested.Multiple linear regression models based on structural parameters were established to predict the fabric sound absorption coefficient,the main research contents were as follows:(1)Preparation and properties characterization of Chenille/Polyester composite yarn.Six kinds of composite braided yarns were designed and prepared,and the basic properties(diameter,braided angle,etc.),tensile fracture properties,friction properties,and bending properties of composite yarns were tested.The results showed that the diameter and braided Angle of Chenille/polyester composite yarns decreased with the increase of pitch,and showed a linear correlation(R~2>0.8);The strength utilization rate of samples 1-1,1-2,1-3(Chenille:polyester=3:1)was higher than that of samples 2-1,2-2,2-3(Chenille:polyester=4:1),and when the pitch was 6mm or 7mm,the strength utilization rate was up to 98%.The dynamic friction coefficients of samples 1-1,1-2,1-3 were lower than that of samples 2-1,2-2,2-3(Chenille:polyester=4:1).When the pitch was 6mm,the dynamic friction coefficient was the lowest,and the average value was 0.38.In terms of bending properties,samples 2-3 and 1-2 have the lowest bending stiffness.The above results showed that the two types of samples have good braided property.(2)Study on the preparation and acoustic properties of ribbed knitting sound absorbers.Using three kinds of braided composite yarns as raw materials,11 kinds of sound absorbing materials with different structural parameters were designed and prepared,and their basic properties,air permeability,porosity and sound absorption coefficient were tested.Through linear regression analysis,single-factor analysis and multiple linear regression analysis of fabric sound absorption coefficient and structural parameters were carried out.The results showed that the order of correlation between the sound absorption performance of Chenille/polyester rib fabric and the structural parameters was as follows:thickness>Surface density>Porosity>Air permeability;The multiple linear regression model of air permeability,porosity,surface density and thickness and the sound absorption coefficient of rib fabric was established.The correlation coefficient R~2 between the predicted value and the measured value reached 0.854,which had a certain degree of confidence.In conclusion,the multiple linear regression model of fabric structure parameters can be used to predict the sound absorption coefficient.(3)Study on the preparation and acoustic properties of mi-lano ribbed knitting sound absorbers.Using Chenille/polyester composite yarn as raw material,11 kinds of mi-lano fabrics with different structural parameters were designed and prepared.The basic properties,permeability,porosity and sound absorption coefficient of mi-lano fabric were tested,and the single factor analysis and multiple linear relationship between sound absorption coefficient of mi-lano fabric and structural parameters were carried out by linear regression analysis.The results showed that there was no significant correlation between the sound absorption coefficient and the thickness,surface density,porosity and permeability of mi-lano fabric.The correlation coefficient R~2of multiple linear regression model was also lower than that of rib fabric.In conclusion,Chenille/polyester composite yarns were introduced to prepare a new type of knitted rib fabric sound absorber,which provides reference for textile applications in the field of sound absorption and noise reduction. |
PDF Full Text Request