活性炭纤维材料吸声性能分析

为研究活性炭纤维的吸声性能,在同一工艺条件下制备了不同规格粘胶基活性炭纤维毡,用传递函数法在250～1 600 Hz中低频率声波范围内采用阻抗管对活性炭纤维材料的吸声性能进行测试,分析材料比表面积、厚度、面密度、空腔厚度等参数对吸声性能的影响。结果表明:活性炭纤维毡多孔材料具有较好的吸声性能,其对声波中频段的吸声好于低频段,随材料的比表面积、厚度、面密度、空腔厚度的增加,其吸声性能越好,但平均吸声系数增幅不同。     

活性炭纤维材料声学特性参数研究

为了分析活性炭纤维材料两个最基本的声学特性参数传播常数和特性阻抗,根据声波在活性炭纤维材料中传播的基本理论,通过运动方程和连续性方程,建立了传播常数和特性阻抗理论模型;利用阻抗管测试活性炭纤维材料在频率声波范围内表面阻抗,采用两倍厚度法确定活性炭纤维材料传播常数和特性阻抗,并对两个声学特性参数的理论和试验结果进行对比分析,结果表明声学特性参数理论模型具有可行性,为开发和设计活性炭纤维吸声材料提供理论依据。     

活性碳纤维材料吸声理论模型建立

参照圆管理论模型,以活性碳纤维毡内部微小通道为基础,确定活性碳纤维材料微孔中空气有效密度和有效压缩模量,建立活性碳纤维材料的吸声理论模型。接着,利用双通道阻抗管声学分析仪,测试活性碳纤维毡在250～6 300 Hz声波频率范围内的吸声系数,对比并分析计算的理论值和实测值。结果发现:理论值与实测值基本一致,这表明建立的活性碳纤维材料的吸声理论模型具有可行性。该模型可为设计和开发活性碳纤维吸声材料提供理论与技术支持。     

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。     

大麻纤维的吸声性能研究

为比较大麻纤维的吸声性能,采用驻波比法测试了大麻、羊毛和棉纤维在中、低频段下的吸声系数,研究了纤维层厚度、容重、后背空腔和孔隙率对吸声系数的影响。结果表明,增加大麻纤维层厚度、容重、后背空腔尺寸,均可提高大麻纤维在中、低频段的吸声系数。纤维层厚度增加,共振吸收频率向低频方向移动;容重增加,吸声系数开始时增加比较明显,随后增幅趋缓;孔隙率增加,大麻纤维吸声系数逐渐增大。当容重、厚度相同时,大麻纤维的吸声性能要比羊毛和棉纤维的吸声性能差。     

废弃苎麻纤维吸声复合材料的制备及其性能分析

以废弃苎麻纤维为增强材料,乙烯-醋酸乙烯酯共聚物为基体材料,使用热压工艺制备废弃苎麻纤维/乙烯-醋酸乙烯酯共聚物吸声阻燃复合材料。设计实验以吸声系数为评测标准,测得最佳的工艺参数为:热压温度125℃,热压压力8 MPa、热压时间25 min、苎麻纤维质量分数45%、材料密度0.204 g/cm~3、材料厚度25 mm、后空气层厚度10 mm。最优工艺条件下,材料的平均吸声系数为0.48,降噪系数为0.50,最高吸声系数可达0.9以上,为废弃苎麻纤维的回收利用提供了新的利用途径,可将其制造成新型吸声材料来治理噪声污染。     

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。     

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。     

棕榈纤维毡/聚(3-羟基丁酸酯-co-3-羟基戊酸酯)热压复合材料的吸声性能

为缓解当前我国汽车内饰用黄麻吸声复合材料产量缩减的现状,研究了棕榈纤维毡/聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(PHBV)热压复合材料的吸声性能。在分析Johnson-Allard吸声模型后,研究了棕榈纤维毡与PHBV质量比、棕榈纤维毡面密度、棕榈纤维线密度、棕榈纤维毡梯度结构、多孔粉煤灰陶粒等对热压复合材料吸声系数的影响;探讨了优化工艺下棕榈纤维毡/PHBV热压复合材料的结构和性能。结果表明:当棕榈纤维毡与PHBV质量比为40∶60,棕榈纤维线密度为14.5 dtex,棕榈纤维毡梯度结构为143.3/102.5 g/m²时,制备的复合材料的平均吸声系数(200~1 600 Hz)最高,可达到0.53,添加质量分数为5%的多孔粉煤灰陶粒,可将复合材料的平均吸声系数提高到0.66,具有部分替代黄麻制备吸声复合材料的潜力。     

车用废纺双密度毡吸声隔声性能研究

利用涤棉混纺纤维制得由一层紧密毡料和一层蓬松毡料构成的双密度毡,并测试了双密度毡的吸声和隔声性能.测试结果表明:双密度毡对高频噪声的吸收效果较好,而对低频噪声的吸收效果较盖;在一定范围内增加双密度毡的厚度,可以相应提高其吸声性能;材料的隔声性能与自身构件的振动频率有关,本试验样品的最高和最低隔声量分别出现在声波频率为3...     

活性碳纤维材料吸声性能影响因素分析

为了研究活性碳纤维毡的吸声性能,选取了7种不同规格的黏胶基活性碳纤维毡,采用阻抗管在250~6 300 Hz频率声波范围内对活性碳纤维毡吸声系数进行测试,分析厚度、密度和纤维直径等因素对吸声性能的影响。研究发现:活性碳纤维毡具有很好的吸声性能;随着厚度和密度的增加,以及纤维直径的减小,活性碳纤维毡吸声性能提高。采用灰色关联度分析得到活性碳纤维毡三个不同因素对吸声性能的影响程度由大到小依次为纤维直径、厚度和密度。     

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 influence of production parameters on sound absorption of activated carbon fiber felts

Intended to study the influence of different production parameters on sound absorption of activated carbon fiber felts, viscose-based activated carbon fiber felts acquired from different production parameters were prepared and taken to test the sound absorption coefficients in normal incidence by means of transfer function method, within an acoustic range of 250–6300 Hz in the impedance tube. Analysis was made to find the influence of carbonization temperature, carbonization rate, activation temperature, and activation time on sound absorption properties. Sound absorption coefficients at medium–low frequencies strikingly climbed with the increasing frequency, while fluctuating at high frequencies. Other production parameters remaining constant, sound absorption coefficients increased at medium–low frequencies with the rising carbonization temperature and the extended activation time, while subsequently decreased with the rising carbonization rate and carbonization temperature. At the same time, sound absorption coefficients decreased at high frequencies with the rising carbonization temperature and carbonization rate, while increased but later decreased with the rising activation temperature, and increased again with the added time in activation.     

Effects of different parameters on acoustic properties of activated carbon fiber felts

The aim of this study is to explore the effects of different parameters on acoustic properties of activated carbon fiber felts. Seven viscose-based activated carbon fiber felts with different specifications were selected to test the sound absorption coefficients in normal incidence by using transfer-function method and an impedance tube in an acoustic range of 250–6300?Hz frequencies, and to analyze the effects on acoustic properties caused by factors such as: thickness, bulk density, and fiber diameter. The result demonstrated that activated carbon fiber felts exhibited exceptional acoustic properties. As frequency increases, sound absorption coefficients of less-thick felts went upwards in the whole range of frequencies; when the thickness amounted to 9?mm, sound absorption coefficients showed a sharp increase at low frequencies and a fluctuation at high frequencies. With the increase in thickness and bulk density, sound absorption properties improved first and then impaired at the same level of frequency; with a decrease in the fiber diameter, properties enhanced at the same level of frequency. When thickness and bulk density increased and fiber diameter decreased, sound absorption coefficients of the first resonance frequency displayed an upward trend to different degrees, while the first resonance frequencies declined discrepantly.     

梯度结构活性碳纤维毡吸声性能分析

为研究梯度结构活性碳纤维毡的吸声性能,选取5种不同密度的粘胶基活性碳纤维毡,两两组合构成梯度结构,借助阻抗管在250~6 300 Hz频率声波范围内,对梯度结构活性碳纤维毡法向入射吸声系数进行测试,分析梯度方向、密度、结构对吸声性能的影响。结果表明:总密度相同的情况下,在低频段单一结构活性碳纤维毡吸声性能比正梯度结构好,但比倒梯度结构差,而在高频段单一结构吸声性能比正梯度结构差,但比倒梯度结构好;总密度不同的情况下,在低频段随着梯度结构总密度的增加,其吸声系数增加,而在高频段随着梯度结构第1层密度的增加,其吸声系数减小;随着活性碳纤维毡第1层密度的增加,第一共振频率向低频移动,随着总密度的增加,第一共振吸声系数增加。     

木棉及其混合纤维非织造材料吸声预测模型

以Allard模型为基础,采用等效流体的方法,拟建立一个能够准确描述木棉及其混合纤维非织造材料吸声行为的吸声模型。该模型结合木棉纤维的大中空结构,考虑了材料的热传导效应及纤维框架的柔软性。使用新建立的吸声模型及Allard模型分别对4种不同结构的木棉纤维非织造材料的吸声系数及比表面阻抗进行了计算,并将计算值与实验样品的测量值进行比较。结果表明:新模型的计算结果更接近实验值,说明新模型更适用于木棉及其混合纤维非织造材料吸声性能的预测,为工业产品的设计提供了理论参考。     

Establishment of acoustic characteristic model of activated carbon fiber felts

Abstract

In order to analyze two basic characteristic acoustic parameters of activated carbon fiber felts: propagation constant and characteristic impedance, the theoretical model of characteristic impedance concerning the two parameters was established by means of motion and continuity equations based on the propagation theory of acoustic waves in activated carbon fiber materials. On the basis of acoustic theories proposed by Zwikker and Kosten, taking into account of the vibrating influence occurring among fibers and modifying the effective air density and the effective bulk modulus, theoretical model of characteristic acoustic parameters of activated carbon fiber materials was established. Surface acoustic impedance was tested with an impedance tube when activated carbon fiber materials were subjected to an acoustic range of 250–2500?Hz frequencies, then propagation constant and characteristic impedance of activated carbon fiber materials were defined by the method of double thickness. Statistics of two acoustic characteristic parameters in theory and trial were compared and contrasted, which showed that the theoretical model had its feasibility and could provide reference for developing and designing the activated carbon fiber materials with sound absorbing properties.