Sound transmission loss through double glazing windows in low frequency range: comparison between finite element and experimental results

2019 ◽  
Author(s):  
Jean-François Deü ◽  
Rubens Sampaio
Keyword(s):  
Finite Element ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Transmission ◽  
Experimental Results ◽  
Sound Transmission Loss ◽  
Frequency Range

scholarly journals Analysis of the transmission loss of double-leaf panels with an equivalent spring–mass model for studs

2020 ◽  
Vol 37 ◽  
pp. 126-133
Author(s):  
Yuan-Wei Li ◽  
Chao-Nan Wang
Keyword(s):  
Distribution Curve ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Experimental Results ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Mass Model ◽  
Steel Stud ◽  
Panel Thickness ◽  
Stiffness Distribution

Abstract The purpose of this study was to investigate the sound insulation of double-leaf panels. In practice, double-leaf panels require a stud between two surface panels. To simplify the analysis, a stud was modeled as a spring and mass. Studies have indicated that the stiffness of the equivalent spring is not a constant and varies with the frequency of sound. Therefore, a frequency-dependent stiffness curve was used to model the effect of the stud to analyze the sound insulation of a double-leaf panel. First, the sound transmission loss of a panel reported by Halliwell was used to fit the results of this study to determine the stiffness of the distribution curve. With this stiffness distribution of steel stud, some previous proposed panels are also analyzed and are compared to the experimental results in the literature. The agreement is good. Finally, the effects of parameters, such as the thickness and density of the panel, thickness of the stud and spacing of the stud, on the sound insulation of double-leaf panels were analyzed.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

scholarly journals Low-Frequency Broadband Sound Transmission Loss of Infinite Orthogonally Rib-Stiffened Sandwich Structure with Periodic Subwavelength Arrays of Shunted Piezoelectric Patches

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Zhifu Zhang ◽  
Weiguang Zheng ◽  
Qibai Huang
Keyword(s):  
Sandwich Structure ◽  
Transmission Loss ◽  
Virtual Work ◽  
Low Frequency ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Convergence Criterion ◽  
Sound Transmission Loss ◽  
Space Harmonic ◽  
Broadband Sound

This paper studies low-frequency sound transmission loss (STL) of an infinite orthogonally rib-stiffened sandwich structure flexibly connected with periodic subwavelength arrays of finite shunted piezoelectric patches. A complete theoretical model is proposed by three steps. First, the panels and piezoelectric patches on both sides are equivalent to two homogeneous facesheets by effective medium method. Second, we take into account all inertia terms of the rib-stiffeners to establish the governing equations by space harmonic method, separating the amplitude coefficients of the equivalent facesheets through virtual work principle. Third, the expression of STL is reduced. Based on the two prerequisites of subwavelength assumption and convergence criterion, the accuracy and validity of the model are verified by finite element simulations, cited experiments, and theoretical values. In the end, parameters affecting the STL performance of the structure are studied. All of these results show that the sandwich structure can improve the low-frequency STL effectively and broaden the sound insulation bandwidth.

Sound transmission loss characteristics of sandwich aircraft panels: Influence of nature of core

2016 ◽  
Vol 19 (1) ◽  
pp. 26-48 ◽  
Author(s):  
MP Arunkumar ◽  
Jeyaraj Pitchaimani ◽  
KV Gangadharan ◽  
MC Lenin Babu
Keyword(s):  
Sandwich Panel ◽  
Transmission Loss ◽  
Sheet Material ◽  
Low Frequency ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Honeycomb Core ◽  
Transmission Characteristics ◽  
The Impact

Sandwich panel which has a design involving acoustic comfort is always denser and larger in size than the design involving mechanical strength. The respective short come can be solved by exploring the impact of core geometry on sound transmission characteristics of sandwich panels. In this aspect, the present work focuses on the study of influence of core geometry on sound transmission characteristics of sandwich panels which are commonly used as aircraft structures. Numerical investigation has been carried out based on a 2D model with equivalent elastic properties. The present study has found that, for a honeycomb core sandwich panel in due consideration to space constraint, better sound transmission characteristics can be achieved with lower core height. It is observed that, for a honeycomb core sandwich panel, one can select cell size as the parameter to reduce the weight with out affecting the sound transmission loss. Triangular core sandwich panel can be used for low frequency application due to its increased transmission loss. In foam core sandwich panel, it is noticed that the effect of face sheet material on sound transmission loss is significant and this can be controlled by varying the density of foam.

Low-frequency impact sound of timber floors: A finite element–based study of conceptual designs

2020 ◽  
pp. 1351010X2091787
Author(s):  
Jörgen Olsson ◽  
Andreas Linderholt
Keyword(s):  
Finite Element ◽  
Low Frequency ◽  
Sound Transmission ◽  
Human Perception ◽  
Finite Element Simulations ◽  
Building Industry ◽  
Frequency Range ◽  
Floor Surfaces ◽  
The Impact ◽  
Selection Of

Traditionally, product development concerning acoustics in the building industry is measurement oriented. For lightweight floors, frequencies that are lower than the frequency range for heavy concrete floors are an issue. The frequency range of from 50 Hz down to 20 Hz influences the human perception of impact sound in multi-story apartment buildings with lightweight floor constructions, such as timber floors, for example. It is well known that a lower frequency range of interest makes finite element simulations more feasible. Strategies for reducing impact sound tend to be less straightforward for timber floors because they have a larger variation of designs when compared to concrete floors. This implies that reliable finite element simulations of impact sound can save time and money for the building industry. This study researches the impact sound transmission of lightweight timber floors. Frequency response functions, from forces on excitation points to sound pressure in the receiving cavity below, are calculated. By using fluid elements connected to reflection-free boundary elements under the floors in the models, the transmission and insulation can be studied without involving reverberation. A floor model with a hard screed surface will have a larger impact force than a softer floor, although this issue seems less pronounced at the lowest frequencies. To characterize floor surfaces, the point mobilities of the impact points are also calculated and presented. The vibration and sound transmission levels are dependent on the selection of the excitation points.

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