双层复合非织造材料基吸声体吸声性能研究

以熔喷丙纶非织造材料和玻璃纤维水刺非织造材料为受声面和背衬层,通过热粘合方式制成双层复合非织造材料基吸声体。通过分析吸声体受声面和背衬层非织造材料的厚度、面密度、孔径、孔隙率等结构参数与复合吸声体的吸声系数之间的关系,探讨各层非织造材料结构参数对复合吸声体吸声性能的影响。实验结果表明,随着熔喷丙纶非织造材料和玻璃纤维水刺非织造材料厚度和面密度的增加,吸声体中高频段吸声系数显著提高;受声面和背衬层的孔径尺寸和孔隙率的变化对双层复合非织造材料基吸声体的吸声性能影响较为显著。     

结构参数对非织造材料吸声系数的影响

分别以涤纶针刺法非织造材料和丙纶熔喷非织造材料为基,通过热粘合方式制成不同参数的同质非织造材料吸声体。通过分析同质非织造材料吸声体的厚度、面密度、孔径、孔隙率等结构参数与其平均吸声系数之间的关系,探讨非织造材料结构参数对其吸声性能的影响。实验结果表明,对于同种材料而言,涤纶针刺非织造材料与丙纶熔喷非织造材料的结构参数对其平均吸声系数具有较大影响,材料的平均吸声系数随厚度和面密度的增加而增加。     

分层复合水刺/热风非织造材料的吸声性能研究

以水刺非织造材料、热熔纤网和热风非织造材料为原料,分层叠加,置于烘箱中热风加热,制得两层和三层复合非织造材料。对分层非织造材料的厚度、透气性、孔隙率以及吸声性能等进行测试,探讨各因素对材料吸声性能的影响。测试结果显示:随着非织造材料厚度增加,同一声波频率的吸声系数提高;单层非织造材料的吸声系数随声音频率的增大而提高;双层复合材料吸声系数随着热风非织造材料面密度增加而提高,最高吸声系数向低频段偏移,吸声频段拓宽,吸声系数随着频率增加呈先上升再下降的趋势;双层分层吸声材料选择孔隙率梯度从受声面开始由低到高排列,三层复合材料的孔隙率按照低—高—低排列,可获得较好的吸声效果。     

针刺非织造材料形态与组合结构对材料吸声性能的影响

利用驻波管测试方法研究了几种不同厚度、不同密度和两种不同类型的纤维材料及其组合结构的吸声性能。研究结果表明,材料厚度的单因子条件与材料的吸声系数呈正线性相关;随着材料体积密度的增加,中低频声波的吸声系数提高,而高频声波的吸声系数呈现先提高后降低的趋势;材料的组合结构对材料的吸声性能影响很大,由中空纤维制成的低密度非织造材料与高密度非织造材料组合,并将高密度非织造材料置于表面,该组合方式的材料其吸声性能明显优于其他几种组合方式的材料。     

丙纶基熔喷非织造材料吸声性能研究

以丙纶熔喷非织造材料为研究对象,通过阻抗管声学分析仪测试非织造材料的吸声性能,研究成核催化剂、中空涤纶短纤及涤纶熔喷非织造材料和丙纶熔喷非织造材料之间的组合结构对丙纶熔喷非织造材料吸声性能的影响.并通过分析其吸声系数的变化,探讨了提高丙纶熔喷非织造材料的吸声性能的途径.     

纺黏非织造材料复合穿孔板吸声性能测试

在一定空腔深度条件下,利用阻抗管对贴有纺黏非织造材料的复合穿孔板进行吸声性能测试与分析,并与普通穿孔板以及空腔内填满玻璃纤维的穿孔板进行对比.试验测试结果表明:背后贴有纺黏非织造材料的复合穿孔板的吸声系数高于普通穿孔板以及空腔内填满玻璃纤维的穿孔板,纺黏非织造材料的存在提高了穿孔板中高频的吸声系数且拓宽了吸声频段宽度....     

涤纶非织造吸声材料的吸声性能研究

研究涤纶非织造吸声材料的吸声性能。利用具有细度梯度的涤纶纤维制备了12种非织造吸声材料,测试分析了不同加固方式、纤维细度、针刺密度和材料厚度对涤纶纤维非织造吸声材料吸声性能的影响。结果表明:在所制备的涤纶非织造吸声材料中,采用针刺加固工艺、较细的纤维细度、较小的针刺密度以及较大的材料厚度,可以获得更好的吸声效果。认为:涤纶纤维可以作为非织造吸声材料应用,其吸声性能较好。     

汽车用吸声非织造材料的应用现状及发展趋势

阐述汽车车厢内噪声的来源、危害及控制方法,详述非织造材料的吸声原理及其在汽车控声领域的具体应用,以及国内外吸声非织造材料的发展历程,介绍目前国外汽车用吸声非织造材料的开发情况,并对国内汽车用吸声非织造材料发展趋势进行预测。     

聚酯纤维针刺非织造材料的吸声性能研究

主要研究了聚酯纤维针刺非织造材料在200~2 000 Hz声波频率范围内的吸声性能。从材料的厚度、针刺密度、表面粗糙度和组成纤维四方面来研究其吸声性能的影响因素。由实验得出,非织造材料的吸声性能主要取决于材料的厚度和表面特征,组成纤维也有一定的影响作用。     

Study on the effects of denier and shapes of polyester fibres on acoustic performance of needle-punched nonwovens with air-gap: comparison of artificial neural network and regression modelling approaches to predict the sound absorption coefficient of nonwovens

In this article, a comparative analysis of artificial neural network (ANN) and regression modelling approaches has been carried out to predict the sound absorption coefficient (SAC) of nonwovens plus air-gap at wide range of frequencies (50–6300?Hz). Needle-punched nonwoven fabrics were produced with different denier and cross-sectional shapes of polyester fibres to study their combined effect on acoustic performance of nonwovens. The surface area of fibres, specific airflow resistance and mean flow pore size of nonwovens were analysed to explain their sound absorption behaviour. Finer fibre nonwovens perform better than the coarser fibre nonwoven as sound absorber. The effective surface areas of fibres in the nonwoven structure greatly affects the SAC. Finer fibres will get aligned easily in z-direction compared to coarser fibres, facilitating formation of more tortuous channels in the fabric structure contributing damping of sound waves. It has been observed that ANN model predicts the SAC with high degree of accuracy than the regression model. The ranking of input parameters in predicting SAC of nonwovens was analysed. Both the models ranked frequency of sound is the major determinant for predicting SAC followed by specific airflow resistance of nonwoven fabric.     

多层复合吸声结构的制备与性能研究

将穿孔板与氯化聚乙烯/七孔涤纶纤维复合材料进行复合制备了一系列的无后部空腔层的多层复合吸声结构。采用SW230驻波管运用传递函数法测试了复合吸声结构的吸声性能,分析了不同组合层数、组合方式、复合材料厚度以及穿孔板的孔隙率对吸声性能的影响。研究结果表明：在双层复合结构中,当穿孔板为测试面时,其吸声性能呈现多孔材料的特性;而测试面为复合材料时,吸声结构具有膜空腔共振的特性;当穿孔板层数超过二层时,复合吸声结构能将多孔材料吸声机理和共振吸声机理进行有机结合从而拓宽了其的吸声频域。是一种具有工程应用潜力的吸声结构。     

废弃纤维吸声复合材料的制备及其吸声性能

针对废弃纺织纤维利用率不高的问题,采用共混-热压工艺,以废弃纤维为增强材料,以热塑性聚氨酯为基体材料,制备废弃纤维/聚氨酯复合材料。将废弃纤维/聚氨酯复合材料加工成穿孔板,并与废弃涤纶织物贴合,构成吸声复合材料。重点研究吸声复合材料中穿孔直径、穿孔板厚度、穿孔率及废弃涤纶织物层数四种结构参数对材料吸声性能的影响。结果表明,穿孔直径主要影响吸声材料的吸声系数峰值;穿孔板厚度、穿孔率和废弃涤纶织物的层数主要影响吸声材料的吸声频带范围。     

水刺非织造布复合技术发展研究

水刺技术在非织造布生产领域非常具发展潜力和前景,而复合则是非织造技术生产高性能和高功能性产品的一种常见方式。介绍各类水刺复合技术的研发状况及其应用。     

Sound absorption properties of composite structure with activated carbon fiber felts

This paper is intended to study the influence of different factors on the sound absorption properties of composite structure with activated carbon fiber felts. Activated carbon fiber felts made from viscose fiber mats were prepared and later combined with perforated panels to form four different composite sound absorption structures. Based on the transfer function method, the impedance tube was used to test the sound absorption coefficients of composite structure in an acoustic range of 80–6300?Hz frequencies. Analysis was made to discuss the influence of such factors on the sound absorption properties as the position of activated carbon fiber felts, thickness, and air space. The results demonstrated that the composite structure displayed different sound absorption properties at different frequencies. Perforated panels played the dominant role in sound absorption by the occurrence of resonance at 80–3500?Hz frequencies, while porous materials contributed the most at 3500–6300?Hz frequencies. At 80–3500?Hz frequencies, the best performance could be observed in the third type of composite structure with changes in the position of activated carbon fiber; the first resonance frequency of the first type of composite structure and perforated panel structure was basically the same, and that of the remaining three types significantly shifted towards the low frequencies with the same scale. In smaller thickness range, with the increase in the thickness of activated carbon fiber felts, sound absorption coefficients of the first and second types of composite structure increased, the first resonance frequency of the first type showing no apparent shift towards the low frequencies compared with what was shown in the second type; but when the thickness arrived at 15.6?mm, sound absorption properties of the composite structure had similar traits to that performed by porous materials in an acoustic range of 80–6300?Hz frequencies. With the increase in the distance of air space, sound absorption properties were improving at 80–650?Hz frequencies but decreasing at 650–3500?Hz frequencies, the first resonance frequency moving towards the low frequencies. At 3500–6300?Hz frequencies, as the position of activated carbon fiber felts and the distance of air space varied, sound absorption coefficients were basically unchanged; while as thickness increased, sound absorption coefficients improved.     

The acoustic characteristics of dual-layered porous nonwovens: a theoretical and experimental analysis

The normal incidence sound absorption coefficient of single-layered porous materials predicted using some prediction models is well known. The published acoustic behaviors prediction models, such as Biot model, Zwikker and Kosten model, Delany and Bazley model, and Champoux and Allard model, can give acceptable prediction results by only taking specific flow resistivity and material thickness as independent variables to estimate the normal incidence sound absorption coefficient. However, the existing literature fails to provide proper knowledge regarding the acoustic characteristics of dual-layered porous nonwoven absorbers. So, the aim of this paper was to propose a theoretical acoustic model for dual-layered porous nonwoven absorber and to verify the proposed model experimentally. In theory aspect, the study focused on the extension algorithm of the Zwikker and Kosten model for dual-layered nonwoven absorber. The theoretical analysis of the impact of thickness and porosity of outer and inner layer on sound absorption coefficient was detailed using numerical simulation method. In experiment aspect, we particularly designed 20 dual-layered nonwoven absorbers with four types of meltblown polypropylene nonwoven materials and five types of hydroentangled E-glass fiber nonwoven materials firstly. Secondly, the calculated sound absorption coefficients using the proposed model were compared with the measured ones of the 20 dual-layered nonwoven absorbers at 250, 500, 1000, and 2000?Hz. Experimental results indicate that the measured and the calculated data have very similar trend with the change of thickness, porosity, and the sound frequency, apart from the obvious difference between them at low frequency.