Abstract With the development of green buildings, people pay more attention to the quality of the indoor sound environment. The air sound insulation performance of floors and exterior walls plays a ...key role in today's green buildings. The thermal performance of the enclosure structure's floor and exterior wall heat transfer resistance is an important factor in reducing building carbon emissions in green buildings. The aim of this paper is to study the efficiency of the acoustic and thermal insulation of a foaming system with porous carbon balls and the combination of different structural ways of construction boards and external walls. The acoustic and thermal parameters of different sound insulation and thermal insulation systems designed with porous carbon sphere foam and inserted into the floors and exterior walls are compared to highlight the optimal structure. The theoretical and experimental tests showed that to improve the sound insulation performance of the floor, a sound insulation system needs to be placed on the surface of the floor in contact with the impact object and inlaid in the vertical gap in contact with the floor and the wall. Furthermore, it has been determined that the surface of the foam particle acoustic ball with micropores has good sound absorption performance. Finally, the high-quality building thermal insulation material with low thermal conductivity in any combination with the floor slabs and the external wall structure improves the thermal insulation performance.
•The artificial neural network method is used to quickly predict the sound insulation performance of aramid honeycomb sandwich panel.•Backpropagation neural network are unable to predict the local ...characteristics of sound insulation performance.•Radial basis function neural network has over fitting in the case of less training data.•The general region neural network has the best prediction effect, with a prediction error of 3.45%throughout the whole frequency range.
When designing or optimizing the aramid honeycomb sandwich panel, it is necessary to predict its sound insulation performance in a wide frequency range (generally 100–5000 Hz). According to the structural characteristics of aramid honeycomb sandwich panels, 49 kinds of aramid honeycomb sandwich panels were designed by the orthogonal test method, and their sound insulation properties were tested. A backpropagation neural network model, a radial basis function neural network model and a general region neural network model are established with the panel material, panel thickness, core material thickness, honeycomb cell diameter, core material density, and acoustic frequency as the input of the artificial neural network model and the sound transmission loss as the output of the artificial neural network model. The results show that the general region neural network model has the highest prediction accuracy, the RMS error value is 3.45%, the prediction effect of the radial basis function neural network is poor, and the RMS error value reaches 11.48. The backpropagation artificial neural network has over fitting in the training process. Thus, it cannot be used to predict the sound insulation performance of the aramid honeycomb sandwich panel under the current data volume.
Abstract
Surface coating of damping paint is a common method to suppress structural vibration and reduce noise, but damping paint has poor thermal conductivity which limits it’ s application to ...transformers, reactors and other equipment that have high requirements for heat dissipation. In this paper, a new type of high thermal conductivity damping coating is prepared by emulsion polymerization, among which, a polyurethane emulsion with internal cross-linking structure and an acrylic emulsion with polymerization function are used as main agents, mica powder is used as the main damping function filler. By adjusting the proportion of non-metallic thermal conductive filler Al
2
O
3
and thermal conductive fiber to explore the influence of different thermal conductive fillers on the thermal conductivity and damping performance of the damping coating. The paint is applied to aluminum and iron plates, and the sound insulation capacity is tested to study the influence of paint thickness, fiber addition, fiber type, viscoelasticity, and temperature aging on the sound insulation performance of damping sound insulation panels. The test results show that by adding thermally conductive filler Al
2
O
3
and thermally conductive fibers, a thermally conductive network chain is formed inside the damping coating, which greatly improves the thermal conductivity of the coating while ensuring the damping performance and the effect of vibration and noise reduction.
•Filling glass wool or stone wool has no obvious effect on its sound insulation.•Effect of wall panel on sound transmission loss in higher frequency band.•Influence of cavity filling materials on ...resonance frequency of wall panel.
To create a healthy and comfortable indoor environment, higher requirements are put forward for the airborne sound insulation performance of buildings. The control of airborne noise transmission is a key measure to improve the airborne sound insulation performance of buildings. In this study, the airborne sound insulation performance of the lightweight double leaf wall was studied, and the influence of stud type, stud spacing, cavity filling (type and thickness of filling materials), panel layers (type, layer number, thickness and mass) on the airborne sound insulation performance of the lightweight wall was emphatically analyzed. The test results show that the airborne sound insulation performance of the lightweight double leaf wall can be improved by the following five measures: (1) increasing the stud spacing; (2) expanding the size of the independent panel; (3) using stone wool or glass wool as the filling materials; (4) increasing the number of panel layers or panel mass; and (5) reducing the structural connection.
The sound insulation performance of an electric vehicle’s body system serves as a critical metric for evaluating the noise, vibration, and harshness (NVH) quality of the vehicle. The accurate and ...efficient prediction of sound insulation performance is foundational for undertaking noise reduction design and optimization. Current engineering practices predominantly rely on Computer-Aided Engineering (CAE) methodologies to address this challenge. However, inherent shortcomings such as low modeling efficiency and difficulty in ensuring prediction accuracy often characterize these approaches. In an effort to overcome these limitations, we propose a decomposition framework for predicting the sound insulation performance of the electric vehicle body system. This framework is established based on a comprehensive analysis of the noise transmission paths within the system. Subsequently, the support vector regression (SVR) method is introduced to construct a machine learning model specifically designed for predicting the sound insulation performance of the body system. This approach aims to mitigate the inherent weaknesses associated with the conventional CAE processes using a ‘data-driven’ paradigm. Furthermore, the Multiple Kernel Learning (MKL) method is used to enhance the processing efficacy of the SVR model. The proposed method is validated using practical application and testing on a specific electric vehicle. The results demonstrate commendable performance in terms of prediction accuracy and robustness. This research contributes to advancing the field by presenting a more effective and reliable approach to predicting the sound insulation performance of electric vehicle body systems, offering valuable insights for noise reduction strategies and optimization efforts in the automotive industry.
•The STL curve of the FMPPs has a distinct resonance peak.•Low bending stiffness results in poor sound insulation effects.•The STL curve remains unchanged when the arrangement order transposed ...symmetrically.•Decreasing the perforation rate decreased from the sound source side is beneficial to improve the absorption effect.
It is unlikely to ignore the coupling effect between the structure of the micro-perforated panel (MPP) and the water medium during the application of MPP in the water medium. Theoretical and experimental studies on the sound transmission characteristics of multi-layer flexible micro-perforated panels (FMPPs) under normal incidence conditions were performed. The transfer impedance of finite-sized FMPPs was calculated with the modal superposition method, and the transmission and energy dissipation factor of the FMPPs was derived using the transfer matrix method. Besides, the studies on the effect of panel elastic properties and the arrangement order on the sound insulation performance were carried out. The sound transmission loss (STL) curve remains unchanged when the arrangement order was transposed symmetrically, and it was beneficial to improve the energy dissipation factor when the perforation rate decreased from the sound source side. Theoretical results were verified on a water-filled impedance tube using the two source-location methods.
The influence mechanism of waste rubber particles (WRPs) on the workability, mechanical properties, and sound insulation performance of recycled aggregate sound insulation mortar (RCM) were ...investigated. According to the principle of volume fraction replacement of recycled fine aggregate by 0 to 50%, WRPs with a particle size of 1–4 mm were incorporated in various mixtures of RCM. Each RCM mixture was tested for workability, mechanical, and sound insulation performance. Mercury intrusion porosimetry was used to analyze the distribution of pores and their sizes inside the material, and X-ray diffraction and scanning electron microscopy were used to analyze the characteristics of the interfacial transition zones (ITZs) between the rubber particles and the cement paste. The results showed that, owing to the hydrophobicity of WRPs, greater WRPs content led to greater fluidity of the mortar mix and a smaller water retention rate. Notably, the rubber in the mortar did not contribute to the hydration reactivity of the cement paste, but it changed the crystal morphology and pore structure of ITZ hydration products. The RCM incorporating 3–10% WRPs produced the optimal pore structure through the aggregate effect, which increased its overall compactness and mechanical performance. Further increase of WRP content significantly improved the sound insulation performance while significantly reducing the strength. Moreover, there was a clear logarithmic relationship between the strength and impact sound level index. This new knowledge can be used to prepare RCM that meets the actual strength and sound insulation requirements of the floor. Thus, the resource utilization of solid waste can be expanded.
Geopolymer as an alternative to cement has gained increasing attention. The aim of this article is to study the influence of the silica fume content and activator type on the porous fly ash-based ...geopolymer with silica fume as foaming agent. Geopolymeric foams were fabricated using low-calcium fly ash, silica fume, and sodium-based alkaline activator as initial materials. The designed silica fume contents were 0, 15, 30, and 45 wt % and two kinds of activators of water glass and sodium hydroxide were used for comparison. Phase composition, microstructure, mechanical properties and sound insulation properties of as-prepared bulks were systematically investigated. It was found that, with increasing silica fume content, the density and compressive strength decreased simultaneously, whereas the porosity and sound insulation performance were effectively enhanced. At the silica fume content of 45% with sodium hydroxide as activator, the porosity was increased 3.02 times, and, at the silica fume content of 45% with water glass as activator, the mean sound insulation value of 43.74 dB was obtained.
In order to achieve a balance between sound insulation and ventilation, a novel acoustic metamaterial of air-permeable multiple-parallel-connection folding chambers was proposed in this study that ...was based on Fano-like interference, and its sound-insulation performance was investigated through acoustic finite element simulation. Each layer of the multiple-parallel-connection folding chambers consisted of a square front panel with many apertures and a corresponding chamber with many cavities, which were able to extend both in the thickness direction and in the plane direction. Parametric analysis was conducted for the number of layers
and turns
, the thickness of each layer
, the inner side lengths of the helical chamber
, and the interval
among the various cavities. With the parameters of
= 10,
= 1,
= 10 mm,
= 28 mm, and
= 1 mm, there were 21 sound-transmission-loss peaks in the frequency range 200-1600 Hz, and the sound-transmission loss reached 26.05 dB, 26.85 dB, 27.03 dB, and 33.6 dB at the low frequencies 468 Hz, 525 Hz, 560 Hz, and 580 Hz, respectively. Meanwhile, the corresponding open area for air passage reached 55.18%, which yielded a capacity for both efficient ventilation and high selective-sound-insulation performance.
In this study, for the purpose of applying air milk as a sound insulation material against rain noise on a wooden roof panel covered with galvalume steel plate, an experimental investigation was ...conducted regarding an effect of air milk filling on the sound insulation performance of the panel in comparison with the unfilled conventional method, in which performances of flexural loading, air sound insulation and sound insulation against rain noise of the panels were examined.
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