基于BP神经网络的非织造材料基复合吸声体吸声系数预测

以涤纶针刺非织造材料和聚丙烯熔喷非织造材料为研究对象,通过实验获得其物理结构参数,并将复合前后非织造材料厚度、面密度、孔隙率和孔径作为BP神经网络的输入项,用于预测吸声体的平均吸声系数,同时通过调节输入神经元个数、传递函数和隐含层个数构建了最佳的BP神经网络预测模型。对非织造材料基复合吸声体的吸声性能进行预测,并与测试结果进行了对比。结果表明,运用BP神经网络可以建立较理想的适用于复合吸声体平均吸声系数预测的模型。     

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。     

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。     

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.     

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。     

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....     

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。     

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。     

羊毛及其混合纤维非织造材料的吸声性能

为优化羊毛非织造材料的吸声性能,以羊毛、毛/涤、毛/麻3种纤维制备非织造材料。通过阻抗管对3种非织造材料的吸声性能进行测试,分析了声波频率在250-6 300 Hz范围内,材料的纤维种类、厚度和空腔深度对其吸声性能的影响。结果表明,3种样品的平均吸声系数均大于0.2,纯毛非织造材料的吸声性能略好于毛/涤材料与毛/麻非织造材料;通过增加材料厚度或设置空腔的方式均可提高材料全频段（尤其中低频段）的吸声性能,其中厚度对材料吸声系数的影响程度更大;从环保、材料价格、便于施工等方面考虑,以厚度为6 mm的毛/麻非织造材料作为吸声材料,并设置6 mm的空腔, 即可达到较为优异的低频吸声性能。     

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.     

纳米纤维非织造过滤材料

介绍了纳米纤维过滤材料的特点及其用途;讨论了聚合物用静电纺进行纺丝,制作纳米纤维和纳米纤维网的过程,并讨论了纳米纤维过滤网的物理结构特点。     

非织造布生产设备的技术改造

分析了非织造布生产线存在的设备问题,介绍了针对存在问题进行的一系列技术改造,通过改造提高了设备性能,消除了生产瓶颈,提高了产品质量。     

Acoustic performance of woven fabrics in relation to structural parameters and air permeability

This work deals with the study of the acoustic characteristics of woven fabrics in relation to fabric structural parameters and air permeability. In order to achieve the objectives of the research, sound absorption coefficient of woven fabric samples was determined via impedance tube method. Samples with various pick densities and yarn twist were used. The effect of fabric thickness was analyzed using three and six layered test samples. Results showed that, while for all samples the minimum values of sound absorption were observed at frequency bands of 250 and 2000?Hz, the maximum sound absorption occurred at the frequency of 1000?Hz. Results also indicated that fabrics woven at pick density of 30?thread/cm exhibited higher sound absorption than fabrics woven at other pick densities. It was found that, noise reduction coefficient of three and six layered samples, woven at low pick densities showed significant increases in comparison to those woven at high pick densities. It was also established that samples woven with lower weft yarn twist absorb sound wave more efficiently. It was concluded that fabric air permeability can be used as a criterion of sound absorption behavior of woven fabrics.