Sound Absorption Performance Research Articles

Effects of Incorporating Oil Palm Mesocarp Fiber as Partial Replacement of Fine Aggregate on the Sound Absorption Performance and Mechanical Properties of Standard Concrete

Effects of Incorporating Oil Palm Mesocarp Fiber as Partial Replacement of Fine Aggregate on the Sound Absorption Performance and Mechanical Properties of Standard Concrete

Fabrication of Hydroxyl Modified Hollow Glass Microsphere Composite Isocyanate‐Based Polyimide Foam and Optimization Strategy Based on Different Bonding Mechanisms

ABSTRACTIn this study, the hydroxyl modified hollow glass microsphere (HM‐HGM) is added to different foaming slurries of isocyanate‐based polyimide foam (IBPIF) at varying ratios, and different bonding effects are formed to optimize the dispersion behavior. Then, the novel HGM composited IBPIF (IBPIF/HGM) is prepared. Hydroxyl groups on HM‐HGM establish hydrogen bonding effect with pyromellitic acid dimethyl ester and dimethyl formamide in the white slurry and react with isocyanate groups in the black slurry. The cell structure of IBPIF is altered to improve its sound absorption performance and mechanical behaviors. Compared with IBPIF/HGM‐0, the average cell size of IBPIF/HGM‐1 and BPIF/HGM‐5 decreases significantly. The sound absorption performance and mechanical behaviors of them are improved to some extent. Compared with samples in which the HM‐HGM is added alone to a single slurry, when the dosage ratio of HM‐HGM in black and white slurries is 1:1, IBPIF/HGM‐3 has more uniform cell structure. The change of IBPIF cell structure by the introduction of HM‐HGM and the unique structure of HM‐HGM can enhance the sound absorption performance and mechanical behaviors of IBPIF. The design idea of different bonding mechanisms significantly provides technical assistance to enhance the acoustic performance of polymeric foam materials.

Effects of clogging and cleaning on sound absorption performance of rubberized porous asphalt mixture

ABSTRACT The rubberized porous asphalt mixture (RPAM) has both the sound absorption capacity of air voids and the damping performance of rubber particles, which is a high-potential noise reduction pavement. However, the air voids are inevitably subjected to clogging, resulting in insufficient sound absorption performance. Moreover, it is not clear whether a large amount of rubber particles exacerbates the attenuation of sound absorption performance. Therefore, the purpose of the paper was to explore the attenuation law of sound absorption performance of RPAM under the action of multiple clogging cycles, and then optimise the preparation parameters to improve noise reduction durability. Constant head permeability test was carried out to simulate the clogging process, and manual and high-pressure washing were used to clean the clogged samples. The results showed that the attenuation process of sound absorption coefficient conformed to exponential function. The interconnected air voids were mainly clogged in the fast attenuation phase, and the open voids were clogged in the slow attenuation phase. It was more efficient to clean samples completely clogged than to clean samples clogged for three cycles. More importantly, rubber particles accelerated the attenuation of sound absorption performance during the clogging process. However, the noise reduction durability of RPAM optimised by orthogonal test was significantly improved, even better than that of porous asphalt mixture without rubber particles.

Multifunctional composite paper fabricated by graphene oxide/tannin decorated carbon fiber with excellent electromagnetic interference shielding, antibacterial and sound absorption properties

Considering the distinctive oxidative coupling characteristic of tannin acid, it was used as an interfacial interlayer to build a nano-coating structure on the surface of carbon fiber (CF)using amino-modified graphene oxide (GON) via Schiff base reaction. Furthermore, a kind of multifunctional composite paper (PTCF/GON) with excellent electromagnetic interference shielding, antibacterial and sound absorption properties was fabricated using surface modified CF (TCF/GON) and plant fibers. The increased active groups on the surface of TCF/GON improved its hydrophilicity and enhanced its dispersibility in water, which facilitated to form an effective interconnected conductive network of composite paper via traditional wet forming process. Composite paper fabricated by 30 wt% surface decorated CF (PTCF1.5/GON1.2) achieved an electromagnetic interference shielding effectiveness as high as 43.4 dB in X-band, shielding 99.9 % of incident electromagnetic energy. Meanwhile, PTCF1.5/GON1.2 exhibits good sound absorption performance in specific frequency bands, with a sound absorption coefficient of 0.98 around 1180 Hz. Besides, PTCF1.5/GON1.2 also exhibited excellent antibacterial properties. This strategy provides an economical and practical method for manufacturing multifunctional electromagnetic shielding materials with superior performance.

Tunable underwater sound absorption via piezoelectric materials with local resonators

In recent years, piezoelectric composite materials have been widely used in the design of underwater anechoic coatings due to their adaptability to tuning parameters. However, there are also some shortcomings, such as a single dissipation mechanism, narrow bandwidth, and poor low-frequency sound absorption. This work proposes an acoustic composite structure combining piezoelectric composite materials with local resonance units, which effectively enhances the sound absorption performance of the structure through the coupling effect of the piezoelectric energy consumption mechanism and local resonance mechanism. Compared to conventional acoustic structures, the proposed acoustic composite structure not only has a strong low-frequency sound absorption effect but also enriches the mid-high frequency sound absorption modes by connecting shunt damping circuits. On this basis, the effect of piezoelectric parameters and resonator morphological properties on structural sound absorption performance is further investigated, and the results show that the designed structure has the characteristic of sound absorption performance that is tunable. In addition, key factors affecting the sound absorption performance of the structure have been optimized to achieve better broadband sound absorption performance. This work may provide valuable ideas for the development of low-frequency broadband adjustable underwater sound-absorbing coatings.

Investigation on the Low‐Frequency Acoustic Performance of Polymer Matrix Composite With Metallic Hollow Spheres Under Different Acoustic Stack Structures

ABSTRACTIn this study, various polymer matrix composites (melamine and flexible polyurethane) combined with 316 L stainless steel hollow spheres were prepared using the casting method. The acoustic properties of the fabricated materials were evaluated under low‐frequency conditions (100–1700 Hz) using an impedance tube. The results indicate that sound absorption and insulation performance are significantly influenced by the incident surface material within this frequency range. Notably, sound waves entering through the polyurethane stainless steel hollow sphere surface yield optimal absorption performance, achieving a maximum sound absorption coefficient of 0.74 at 400 Hz. Conversely, the melamine foam surface provides the best sound absorption at higher frequencies within this range, reaching a coefficient of 0.43 at 1700 Hz. The findings highlight the effective sound absorption and insulation capabilities of the composite materials.

Thin-slice structure enhanced hyperelastic composite foams for superb sound absorption and thermal insulation

With the ongoing advancement of society, the populace’s needs for goods are progressively evolving from essential to comfy. Within the construction sector, the demands for building materials with exceptional sound absorption and thermal insulation capabilities are becoming increasingly expected by consumers. Herein, the melamine foam (MF) and carboxymethyl cellulose (CMC) were combined through a facile dip-coating method. Benefitting from the unique three-dimensional porous structure and the folded pore walls caused by CMC, the composite foam with thin-slice structure exhibited a high sound absorption capacity with a noise reduction coefficient of 0.424 (thickness = 20mm). In particular, compared to the unmodified MF, the sound absorption performance of the composite foam was increased by approximately 94.3% at 500Hz and 211.2% at 1000Hz. Furthermore, it also demonstrated outstanding thermal insulation ability with low thermal conductivity of 0.0319W/mK and thermal diffusivity of 0.855 mm2/s. When placed on a heating platform of 145 °C, the temperature difference between the upper and lower surfaces of the composite foam reached an impressive 105.1 °C. Based on these advantages, this high-performance composite foam possesses great potential for applications in engineering, construction, noise reduction, and personal protection.

Modified analytical model for predicting the nonlinear acoustic characteristics of perforated sound-absorption structures at high sound pressures

This paper presents a modified model for predicting the nonlinear acoustic characteristics of a microperforated plate at high sound pressure levels with increased accuracy of PARK Model. Based on PARK Model, the acoustic impedance of the cavity behind the plate is taken into account in the equivalent circuit to adjust the velocity in the perforations. The modified model was compared with the previous model to verify its accuracy at high sound pressure levels. Furthermore, to establish that the proposed model also has higher accuracy when considering perforated structures with complex cavities, a four-unit coupled structure (FUCS) composed of four coiled-up space channels was constructed. A finite-element model was used to verify the accuracy of our proposed model. This confirmed that our model calculates the sound-absorption coefficient and average particle velocity in the microholes more accurately than several other models at 155 dB. Experimental assessments of the sound-absorption performance of the FUCS within the 300–1900 Hz range confirmed the accuracy of the model. When considering perforated sound-absorption structures at high sound pressure levels, this model is more accurate than PARK's Model and, therefore, has potential application value in relation to the extreme noise fields experienced in aerospace applications.

Synthesis of Highly Porous Graphene Oxide-PEI Foams for Enhanced Sound Absorption in High-Frequency Regime.

High-frequency noise exceeding 1 kHz has emerged as a pressing public health issue in industrial and occupational settings. In response to this challenge, the present study explores the development of a graphene oxide-polyethyleneimine (GO-PEI) foam (GPF) featuring a hierarchically porous structure. The synthesis and optimization of GPF were carried out using a range of analytical techniques, including Raman spectroscopy, scanning electron microscopy (SEM), Braunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). To evaluate its acoustic properties, GPF was subjected to sound absorption tests over the 1000-6400 Hz frequency range, where it was benchmarked against conventional melamine foam. The findings demonstrated that GPF with a GO-to-PEI composition ratio of 1:3 exhibited enhanced sound absorption performance, with improvements ranging from 15.0% to 118%, and achieved a peak absorption coefficient of 0.97. Additionally, we applied the Johnson-Champoux-Allard (JCA) model to further characterize the foam's acoustic behavior, capturing key parameters such as porosity, flow resistivity, and viscous/thermal losses. The JCA model exhibited a superior fit to the experimental data compared to traditional models, providing a more accurate prediction of the foam's complex microstructure and sound absorption properties. These findings underscore GPF's promise as an efficient solution for mitigating high-frequency noise in industrial and environmental applications.

Experimental and numerical study on underwater noise control of multigrooved metasurface coating with antifouling and drag reduction potential

Acoustic metasurfaces have garnered increasing attention due to their efficacy in low-frequency sound absorption, while achieving broadband sound absorption performance remains challenging. In this study, a novel approach employing a multigrooved metasurface integrated onto a nanocomposite material is undertaken. Before modification, the nanocomposite material exhibits commendable underwater sound absorption capabilities above 4000 Hz, but demonstrates lower performance below this threshold. Integrating the multigrooved metasurface yields a notable enhancement in sound absorption performance below 4000 Hz, with the average absorption coefficient increasing from 0.29 to 0.63. Remarkably, this enhancement almost does not impact the performance above 4000 Hz. Experimental findings additionally reveal improved performance under variable hydrostatic pressures. Notably, the multigrooved surfaces show enhanced antifouling properties, and also exhibit potential for drag reduction compared to smooth surfaces. The proposed multigrooved metasurface in this study introduces a novel strategy towards the development of multifunctional underwater sound absorption coatings.

Ultra-thin low-frequency broadband absorber based on layered coiled channel structure

To improve and broaden the performance in absorbing sound waves of metamaterials at the lower and mid-frequency ranges, a layered coiled channel composite structure (LCCS) with deep subwavelengths is proposed in this paper, which extends the acoustic wave propagation paths longitudinally by connecting the Helmholtz resonator channels in each layer and achieves the multistep resonance of the coupling cavities, which results in the cancellation of acoustic energies, reduces the acoustic reflections and scattering, and enhances the absorption performance. A model to simulate theoretical sound absorption and finite elements simulation of the metamaterial were evolved to reveal its potential mechanismfor absorbing sound. Using the single-variable method to study the impact of altering structural parameters on the effectiveness of sound absorption, it shows good tunability in the target frequency range and obtains four fundamental unit LCCSs having distinct frequency absorption peaks, and designs a multi-unit coupling construction having low frequencies wideband sound absorption performance by connecting them in parallel to realize a large-broadband continuous and high-efficiency sound absorption within the scope of 370–1400 Hz, using a mean peak sound absorption value higher than 0.7. The structure was put together by 3D printing, and the impedance tube method test verified the precision of the simulation’s findings. This study offers a practical means to create lightweight, low-frequency broadband acoustic absorbing metamaterials.

Inverse-designed acoustic metasurfaces for broadband sound absorption

Acoustic metasurfaces are widely used for noise attenuation due to their outstanding acoustic performance and subwavelength characteristics. The paper introduces a topology-optimized inverse design approach for broadband sound-absorbing metasurfaces, aiming to achieve efficient sound absorption performance across a wide frequency spectrum. By integrating genetic algorithms with the finite element method and driven by objectives such as the absorption frequency range and absorption coefficient, we can transcend the limitations of manual design and fully exploit the design potential of structures. Furthermore, the study investigates the sound absorption mechanism and thermal-viscous dissipation through finite element simulations and experimental validations. The research findings reveal that the proposed broadband sound-absorbing metasurfaces demonstrate excellent sound absorption capabilities across the designated frequency range, boasting an average sound absorption coefficient exceeding 85%. These findings offer fresh perspectives and methodologies for advancing the research and practical application of broadband sound-absorbing metasurfaces.

Electric Field-Induced Ordered-Structural Aerogels Enable Superinsulation and Multifunctionality.

1D flexible fibers assembled 3D porous networked ceramic fiber aerogels (CFAs) are developed to overcome the brittleness of traditional ceramic particle aerogels. However, existing CFAs with disordered and quasi-ordered structures fail to balance the relationship between flexibility, robustness, and thermal insulation. Creating novel architectural CFAs with an excellent combination of performances has proven extremely challenging. In this paper, a novel strategy is adopted to fabricate porous mullite fibrous aerogels (MFAs) with ordered structures by combining fiber sedimentation and electric field-induced fiber alignment techniques. For the first time, electric field-induced alignment of ceramic fibers is utilized to prepare bulk aerogels on a large scale. The resulting MFAs exhibit ultra-low high-temperature thermal conductivity of 0.0830 W m-1 K-1 at 1000°C, anisotropic mechanical and sound absorption performances, and multifunctionality in terms of the combination of thermal insulation, sound absorption, and hydrophobicity. The successful synthesis of such fascinating materials may provide new insights into the design and development of multifunctional CFAs for various applications.

Analysis of Low-Frequency Sound Absorption Performance and Optimization of Structural Parameters for Acoustic Metamaterials for Spatial Double Helix Resonators

Low-frequency noise absorbers often require large structural dimensions, constraining their development in practical applications. In order to improve space utilization, an acoustic metamaterial with a spatial double helix, called a spatial double helix resonator (SDHR), is proposed in this paper. An analytical model of the spatial double-helix resonator is established and verified by numerical simulations and impedance tube experiments. By comparing the acoustic absorption coefficients of the spatial double-helix resonator, it is shown that the results of the analytical model, the numerical model, and the experiments are in good agreement, proving the accuracy of the theoretical model. The effects of different structural parameters on the peak sound absorption coefficient and resonance frequency are quantitatively revealed. The impedance variation law of the model is obtained, and the resistance and reactance distributions at the resonance frequency are analyzed. In the optimization model, the Back Propagation (BP) network is used to construct the mapping between the structural parameters and the resonance frequency and sound absorption coefficient, and this is used as the constraints of the equation, which is combined with Wild Horse Optimization (WHO) to establish the BP-WHO optimization model to minimize the volume of the spatial double helix resonator. The results show that, for a given noise frequency, the optimized structural parameters enhance the space utilization without affecting the performance of the space double helix resonator.

Efficient and broadband sound absorption properties of slotted aluminum foam

To enhance the sound absorption performance of aluminum foam, a slotted structure was developed. Firstly, the theoretical model of sound absorption for the slotted aluminum foam was established by the transfer matrix method. Secondly, the finite element model was established using COMSOL software to predict the sound absorption coefficient. The reliability of the theoretical and finite element models was validated through impedance tube experiments. The sound absorption mechanism is investigated by analyzing the internal sound field. Finally, the sound absorption properties of aluminum foam with other slot patterns are investigated. Additionally, the factors that influence sound absorption properties are investigated. The results indicate that the slots alter the sound pressure distribution within the material, inducing a pressure diffusion effect. When sound waves enter the interior of the material through the narrow slots, they are absorbed and dissipated by the matrix material on the sides of the slots. The sound absorption coefficient can be improved by increasing the thickness, slot scale, and slot depth of the slotted aluminum foam. Specifically, when the slot depth is 15 mm, and the slot width is 5 mm, the average sound absorption coefficient of incompletely slotted aluminum foam in the frequency range of 1000 ∼ 6300 Hz is 0.86, which can realize broadband sound absorption. With the increase of slot depth, the sound absorption peak becomes more pronounced.

Design of ultralight multifunctional sandwich structure with n-h hybrid core for integrated sound absorption and load-bearing capacity

Multifunctionality has become an important evaluating index for structural design because engineering applications in complicated environment call for multifunctional and ultralight structures. With this in mind, this paper proposes a novel ultralight multifunctional micro-perforated sandwich structure with N-H type hybrid cores, which demonstrates superior sound absorption across a wide frequency range, while also achieving good load-bearing capacity. An analytical model is established to calculate the sound absorption coefficient, which is then validated through numerical simulation and experimental measurements. Furthermore, the underlying physical mechanisms for the satisfactory sound absorption are explored. The influences of specific parameters on the broadband sound absorption performance of the proposed structure are quantitatively demonstrated through systematic parameter studies. Additionally, in order to demonstrate the preeminent multifunctional attributes of the proposed structure, a numerical simulation method is employed to evaluate its out-of-plane compression properties. Compared to other micro-perforated sandwiches, the proposed structure exhibits an improvement in load bearing capacity. A radar chart is also created to display the advantages of the proposed micro-perforated sandwich structure over others. Overall, the proposed ultralight sandwich structure with N-H type hybrid cores shows great significance for engineering applications that demand high comprehensive performances owing to its multifunctionality.

Enhancing wave retarding and sound absorption performances in perforation-modulated sonic black hole structures

Sonic black hole (SBH) effects in a retarding duct can be exploited for sound wave manipulation and absorption. The phenomenon relies on two fundamental physical mechanisms: wave speed reduction and energy dissipation. In this study, we demonstrate that these two physical processes can be meticulously balanced through adjusting the perforation parameters in a perforation-modulated SBH (PMSBH). To elucidate the mechanism of slow wave generation and the effect of perforation parameters, an analytic model based on the Wentzel-Kramers-Brillouin (WKB) solutions to the linear acoustic wave equation is established. Alongside transient finite element simulations, the study unveils the roles that major physical parameters play in terms of regulating sound speed and sound absorption. The perforation ratio of the PMSBH is identified as the dominant factor affecting the slow-sound effect, with an optimal range of above 10 % for a PMSBH with densely segmented internal rings. Owing to the inclusion of the perforated boundary, prominent slow wave effects can still be maintained even with a reduced number of rings, provided that the perforation ratio is properly chosen within a reduced variation range. In both cases, the identified perforation ratio largely exceeds the conventional range widely adopted in the micro-perforation community when the slow wave effects are absent. On top of this, tuning the hole size can further enhance air friction for better sound absorption. Theoretical and numerical findings are experimentally validated, and the performance of the PMSBH is demonstrated. While bringing forward the concept of tunable design, this study offers physical insights and guidance for realizing effective sound absorbers embracing slow wave principles and perforation-induced sound absorption.

Micro-perforated plates constructions with approaching the theoretical limits of its sound absorption performance

Micro-perforated plates resonant absorbers have a considerable theoretical sound absorption bandwidth upper limit. Three types of MPPs with straight holes, including circular holes on thick plate, circular holes on thin plate, and slotted holes on thin plate, are investigated with approaching the theoretical limits of its sound absorption performance. It is demonstrated that thin plates are easy to obtain satisfactory sound absorption performance but hard to get high mechanical strength. Slotted holes are beneficial for extending the sound absorption bandwidth of MPP absorbers. MPPs with straight holes usually require a combination of thin plates, minute holes and high perforation ratios, which is practically difficult to apply on a large scale. Two other types of MPPs with variable cross-sectional holes, fabricated using the subtractive processing method and superposition processing method, are then proposed to achieve perfect sound absorption performance and good engineering feasibility.

Experimental study on the acoustic properties of monofilament fabrics

The traditional machining perforated sound absorption structure has high processing cost and inconvenient installation and disassembly, so that how to efficiently and economically manufacture submillimeter micropores still remains a challenge. In this study, a kind of flexible microporous sound absorbing material was obtained by weaving a polymer artificial fiber covered with ethylene polyester fiber, and the relationship between the sound absorption performance of the curtain and the porosity of the pass and fabric was obtained through the finite element simulation model and impedance tube experiment. The mechanism parameters of wide-band flexible microporous material with high sound absorption performance are obtained, which guide the design of a kind of sound absorption material with lower production cost and easy installation and disassembly.

A study on the multi layers of automotive interior trim parts to improve the acoustic performance with microfiber applied to the surface layer

As the world joins environmental regulations, there is an increasing demand for the production of eco-friendly cars. As a result, the driving method of the vehicle was changed from the engine to the electric motor, and the main noise source was changed. In case of existing internal combustion engines (ICE), the low-frequency sound range, which is the engine's main noise, is the main source of sound. As it is converted into an eco-friendly car, the noise that was hidden by the engine combustion sound and the high-frequency noise of the motor are being highlightened. PP meltblown generally has a lower denier than other fibers, so it is effective in improving sound absorption performance because the surfaces of the fibers are large compared to the same weight of another fibers. In conclusion, by applying this PP meltblown fibers to the structure of Dash Insulation, sound absorption performance is improved and resulting in lightweighten effect of Dash Insulation