Sound Transmission Loss Analysis of a Double Plate-Acoustic Cavity Coupling System with In-Plane Functionally Graded Materials

In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.

Development of a High Sound Absorption Material CEMCOM

Based on sound absorption mechanism of material,the special sound absorption material CEMCOM for road sound insulation is introduced.This high sound absorption material is mainly composed of expanded perlite.Using multiple sound absorption structure can improve sound absorption property of material.According to the preparation principle and durability design of material,a new kind of material with low cost and high durability is developed.

Theoretical Calculation and Analysis of Muffler Based on Multilayer Sound Absorbing Material

The multilayer impedance composite sound absorption structure of the new muffler is proposed by combining the microporous plate structure with the resonant sound absorption structure of the porous material.Firstly,the acoustic impedance and acoustic absorption coefficient of the new muffler structure are calculated by acoustic electric analogy method,and then the noise attenuation is calculated.When the new muffler structure parameters change,the relationship among the noise frequency,the sound absorption coefficient and the noise attenuation is calculated by using MATLAB.Finally,the calculated results are compared with the experimental data to verify the correctness of the theoretical calculation.The variation of resonance peak,resonance frequency and attenuation band width of each structural parameter is analyzed by the relation curve.The conclusion shows that it is feasible to use multilayer sound absorbing materials as the body structure of the new muffler.And the influence relationship between the change of various parameters of the sound absorption structure with the sound absorption coefficient and noise attenuation is obtained.

Sound radiation of a functionally graded material cylindrical shell in water by mobility method

Based on the fundamental dynamic equations of functionally graded material (FGM) cylindrical shell, this paper investigates the sound radiation of vibrational FGM shell in water by mobility method. This model takes into account the exterior fluid loading due to the sound press radiated by the FGM shell. The FGM cylindrical shell was excited by a harmonic line radial force uniformly distributing along the generator. The FGM shell equations of motion, the Helmholtz equation in the exterior fluid medium and the continuity equation at fluid-shell interface are used in this vibroacoustic problem. The expressions of sound radiation efficiency and sound field of the FGM shell have been derived by mobility method. Radiation efficiency, modal mobility and the directivity pattern of the sound field are solved numerically. In particular, radiation efficiency and directivity pattern with various power law index are analyzed.

Unleashing the Potential of Unidirectional Mechanical Materials: Breakthroughs and Promising Applications

The emergence of mechanically one-way materials presents an exciting opportunity for materials science and engineering. These substances exhibit unique nonreciprocal mechanical responses, enabling them to selectively channel mechanical energy and facilitate directed sound propagation, controlled mass transport, and concentration of mechanical energy amidst random motion. This article explores the fundamentals of mechanically one-way materials, their potential applications across various industries, and the economic and environmental considerations related to their production and use.

Aerodynamic Sound Radiated from Two-Dimensional Airfoil with Local Porous Material

In the present paper, the attention is focused on the effect of local porous material on aerodynamic sound radiated from two-dimensional airfoil. We measured the aerodynamic sound radiated from the airfoil with porous material, tripping wire and porous plate which are mounted locally on the surface of the airfoils near the leading edge. At the normal airfoil, discrete frequency noise is clearly observed at small attack angle. However, it is clear that its noise generated from the airfoil decreased with the local porous material on the surface of pressure side of the airfoil. The porous material is effective to reduce this noise compared with the others. And the sound absorbing coefficient and the air permeability were measured for test porous material. The sound absorbing coefficient increased at the high frequency band, and the air permeability became small for porous materials. As the attack angle increased, the discrete frequency noise was not generated from the normal airfoil. The broadband noises were almost same for all test airfoils.

Calculation and Analysis of Acoustic Characteristics of Straight-Through Perforated Pipe Muffler Based on Multilayer Sound Absorbing Material

Using the multi-physical field simulation software COMSOL,the acoustic characteristics of the multilayer sound absorbing material straight-through perforated pipe muffler are studied by the finite element method.The results show that the finite element calculation of the multilayer sound absorbing material straight-through the perforated pipe muffler agrees well with the experimental measurement results.The reliability of the finite element method for studying the acoustic performance of the straight-through perforated pipe muffler with multilayer sound absorbing materials is shown.Furthermore,the influence of some structural parameters of porous sound absorbing material and micro-perforated plate on the acoustic performance of the multilayer sound absorbing material straight-through perforated pipe muffler is analyzed.The muffler based on multilayer sound absorbing material is different from the traditional muffler.After applying the multilayer sound absorbing material to the straight-through perforated pipe muffler,the transmission loss value greatly increases,which provides new ideas and directions for future research on the muffler.

Giant Magnetostrictive Material Exciter for Panel Loudspeaker

The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system. The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distributed mode panel is introduced and how exciter parameters influence panel lo＇udspeaker＇ s performance is discussed. Numerical predictions are given in order to show how these influences are manifested.

Preparation of steel slag porous sound-absorbing material using coal powder as pore former

The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5 MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50%（wt.%）, percentage of coal powder of 30%（wt.%）, sintering temperature of 1130°C,and sintering time of 6.0 hr, which were determined by analyzing the properties of the sound-absorbing material.

Calculation of Sound Ray’s Trajectories by the Method of Analogy to Mechanics at Ocean

In this paper, one of analogies available in the literature between movement of a material particle and ray propagation of a sound in liquid is used. By means of the equations of Hamilton describing movement of a material particle, analytical expression of a tangent to a trajectory of a sound ray at non-uniform ocean on depth is received. The received expression for a tangent differs from traditional one, defined under law Snelius. Calculation of trajectories, and also other characteristics of a sound field is carried out by two methods: first—traditional, under law Snelius, and second—by the analogy to mechanics method. Calculations are made for canonical type of the sound channel. In the region near to horizontal rays, both methods yield close results, and in the region of steep slope, the small distinction is observed.

Experimental investigation of sound absorption in a composite absorber

A composite absorber made of a polyurethane sponge and multi-layer micro-perforated plates is pre-sented in this study.Results from an acoustic impedance tube test show that the polyurethane sponge can exhibits higher low-frequency sound absorption in front of the micro-perforated plate,while sound absorption at medium and high-frequencies remains low.The physical mechanism behind this is that the micro-perforated plate increases the denpth cavity.If the polyurethane sponge is placed behind the micro-perforated plate,the amplitude of the original absorption peak will remain constant,but the ab-sorption peaks will shift to lower frequencies.The reason for this phenomenon is that porous materials with low flow resistance can be approximately equivalent to fluid,which not only does not affect the res-onance absorption coefficient of micro-perforated plate,but also makes the peaks move to low frequency.This study has the potential applications in the sound absorption design of composite structure.

木质材料对室内声学调控的研究进展

木材为多孔性材料,在室内空间中,使用木质材料除了具有饰面作用外,还可以有效吸收声能,控制室内混响时间,改善音质,提高语言清晰度。本文概述了木质材料的吸声和隔声性能两方面的研究现状,并对未来的研究提出了建议。在此基础之上,总结了前人在大型建筑空间、小型办公空间、家居室内空间中声环境调控的不足之处。主要有以下3点:1)研究者多选取某一特定的室内空间类型进行声环境改善,尚缺乏对不同使用功能的室内空间声环境的规律性研究,以形成较为系统的室内声环境调控体系。2)成片的家具几何结构改变室内声环境的程度有待进一步研究验证。3)对于改变空间的形状、比例、布局的方法有待进一步研究其内在规律,为设计师、建筑师和科研人员提供参考依据。未来研究重点包括:1)通过使用木质材料对空间进行合理化布局与设计;2)处理好不均匀的声频或室内声场驻波的简并现象,需合理选择吸声构件。3)建立智能化声学仿真模型。

基于压电材料的主动吸声仿真方法研究

主动控制仿真软件很少,大部分控制问题都采用MATLAB自编程进行计算或搭建试验台进行试验,前者仿真结果不可靠,后者需要消耗大量的经费。针对这种问题,该文采用一种新的仿真方法,对圆形和方形压电陶瓷片的主动吸声降噪性能进行对比研究。仿真步骤分三步。第一步,在ANSYS动态分析中获取压电陶瓷片前的两个聚偏氟乙烯(polyvinylidene fluoride,PVDF)压电传感器在当前载荷步下产生的声压和质点振动速度。第二步,将第一步得到的声压和质点振动速度信号导入MATLAB,分离入射声波和反射声波,利用MATLAB自带的最优控制算法计算出需要施加的控制电压。第三步,在ANSYS中将MATLAB计算出的控制电压施加到压电陶瓷片的两端,再次进行动态分析,得到下一个载荷步的两个PVDF压电传感器产生的电压。重复以上三个步骤,就可以模拟出压电陶瓷片的主动吸声控制过程。仿真试验得到了施加在不同形状压电材料上的驱动电压与频率的关系,仿真结果与理论计算结果接近。仿真试验结果表明,在表面积相同的情况下,与方形压电陶瓷片相比,圆形压电陶瓷片的吸声降噪效果更显著。

开发基于亥姆霍兹谐振腔的通风吸声超材料创新性实验

通风吸声超材料是目前解决通风降噪问题的热点研究,可围绕通风吸声超材料的研究方案开展大学物理实验教学。本研究方案采用有限元仿真软件COMSOL Multiphysics理论建模并计算,优化设计基于不完美亥姆霍兹谐振腔的通风吸声超材料,该超材料在调整结构参数后能在低频噪音下实现宽频吸收;利用3D打印技术打印超材料结构,并采用突破黑匣子的实验装置定量测量声学超材料的吸声性能。本文将前沿、热点研究引入大学物理实验教学,模拟、还原科学研究的过程,增强实验的高阶性、创新性和挑战度,采用“小组式自主探究+答辩汇报”的教学模式,全面提升学生的“5C”核心能力。

船用厨余管道包覆材料吸隔声性能试验研究

根据某远洋客船舱室部分厨余管道的案例,试验针对包覆材料和粘接剂研究吸声系数和隔声量在中低频范围内的变化规律,讨论船用厨余管道包覆材料厚度和粘接剂种类选取对吸隔声性能的影响。对比分析发现材料厚度从19 mm提升至25 mm时,吸隔声性能提升最为显著,吸声系数提升约143%,隔声量提升约27%。研究结论为船用厨余管道的安装及材料应用提供一定的技术参考。

PMMA多孔微球改性制备隔声材料研究

以甲基丙烯酸甲酯、偶氮二异丁腈、聚乙二醇、明胶以及钠化、有机化处理后的蒙脱土为原料,制备了聚甲基丙烯酸甲酯/蒙脱土(PMMA/MMT)多孔微球,并将其作为填料其加入液体硅橡胶泡沫材料中,制备出一种隔声材料。通过扫描电子显微镜、BET测试、激光粒度测试、阻抗管法等分析方法,研究了PMMA/MMT多孔微球的结构与性能,以及其掺入对所制备隔声材料对不同频段噪声的隔声性能的影响。结果表明:包覆MMT后的PMMA多孔微球的比表面积、孔容和孔径都得到提高,粒径均一性较好,将其掺入液体硅橡胶泡沫后,材料的中低频隔声性能显著提升,微球掺量为10%的复合材料对500~2000Hz中频段噪声的隔声量(TL)比未掺微球时提高了44%。

超声检测DZ-I国家标准样品研制及测定方法研究

研制无损检测标准样品能够统一检测标准、提高检测精度、保证产品质量。本文借鉴普通标准样品制备技术,结合无损检测的超声波检测标准试块专用标准样品的技术特点,制备了DZ-I标准样品试块,并测定其化学成分、晶粒度、尺寸;选定用声速和声衰减作为DZ-I标准样品试块的定值参数,并采用水浸脉冲反射法、多次反射回波法测量和计算参数。结果显示:DZ-I标准样品试块满足标准要求;测试试块的声速和声衰减可保证DZ-I标准样品试块的一致性与稳定性。在实际应用中,使用这样的标准样品可为超声无损检测过程提供准确可靠的技术依据,确保检测结果的准确性和一致性。

石油开采噪声控制研究与应用

文章详细介绍了钻机噪声源特征、工作场景特征要求、降噪设计关键难点、降噪方案及其成果,可为石油开采、钻探领域噪声控制工程提供借鉴。项目涉及的国际工程中标准的适用问题与解决方案,也可为同类国际项目提供借鉴。

道路声屏障组合吸声结构设计与评估

声屏障在道路交通噪声污染防治中得到了广泛应用,但同时面临材料吸声性能有限、轻量化程度有待提升等问题。为了更好地提升道路声屏障的降噪效果,需要研究组合吸声结构的声学性能及其影响因素。建立了二维阻抗管有限元模型,与实验数据进行对比验证了其可靠性。基于有限元仿真构建了微穿孔板-双层多孔吸声材料-空腔组合吸声结构,研究了几何参数对组合结构的吸声性能的影响,并在实际道路场景中进行了仿真分析。结果表明,微穿孔板的孔径和厚度减小,组合结构在中高频段的吸声效果提升;穿孔率减小,组合结构在低频段的吸声性能提升,但是中高频吸声性能显著降低;多孔吸声材料厚度的增加能提升组合结构中高频吸声系数。在多孔吸声材料背后合理设置空腔并不会降低组合结构的声学性能。穿孔率3%,孔径0.4 mm,板厚1 mm的微穿孔板与3 cm聚酯纤维+3 cm三聚氰胺+2 cm空腔的组合吸声结构降噪效果较好,将其作为吸声型声屏障的材料。吸声型和隔声型声屏障插入损失的规律基本一致,采用组合吸声结构的吸声型声屏障较隔声型声屏障插入损失提升1~2 dB,能够较好地控制中低频交通噪声,具有实际工程价值。

基于多层六边形MAM的变压器降噪方法设计

城市变压器的噪声治理是输变电工程中亟需解决的问题。该研究对某110kV变压器的噪声频谱进行分析,得到变压器噪声主频的分布特性。利用不同类型薄膜声学超材料隔声能力的互补性,设计了一种基于多层六边形薄膜型声学超材料的复合隔声结构。该隔声结构具有体积小、隔声性能强的特点。采用有限元法对六边形薄膜声学超材料建立仿真模型,研究分析薄膜厚度与预应力对其隔声性能的影响,结合分析结果对该材料进行优化。在此基础上,建立复合隔声结构的有限元仿真模型。仿真结果表明,该种复合隔声结构在变压器噪声的主频点均具有较高的声传递损失,最低可达20.4 dB左右,能很好地阻断变压器噪声传播。