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    Tytuł:
    Improving Sound Transmission Through Triple-Panel Structure Using Porous Material and Sonic Crystal
    Autorzy:
    Kim, Myong-Jin
    Powiązania:
    https://bibliotekanauki.pl/articles/177186.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    sound transmission loss
    sonic crystal
    triple-panel structure
    sound insulation
    Opis:
    Main aim of this study is to combine the characteristics of the sonic crystal (SC) with acoustic panels and porous materials to improve the sound transmission loss (STL) through the triple-panel structure. SCs cause a bandgap centered around a certain frequency (Bragg’s frequency) due to generation of destructive interference. Initially, an analytical method is developed that extends the previous theory of double-panel structure to predict STL through a triple-panel structure. Finite element (FE) simulations are performer to obtain the STL through the triple-panel, which are validated with the analytical predictions. Various configurations are analyzed using the FE method based on the method of inserting the porous material and SCs between the panels to address the combined effect. STL through the triple-panel structure is compared with that through the double-panel structure having the same total weight and total thickness. It is found that the combined structure of the triple panel and the SC with glass wool as filler gives the best soundproof performance for the same external dimensions. For narrow air gaps, filing with glass wool is more advantageous than inserting one row of SC. In addition, the triple panel combined with a SC has better soundproofing than the two-panel counterparts.
    Źródło:
    Archives of Acoustics; 2019, 44, 3; 533-541
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relationship Between the Sound Transmission Through the Finite Double-Panel Structure with a Cylindrical Shell Array and the Vibro-Acoustic Characteristics of its Constituents
    Autorzy:
    Kim, Song-Hun
    Kim, Myong-Jin
    Powiązania:
    https://bibliotekanauki.pl/articles/31339804.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    sound transmission loss
    double-panel structure
    eigenmode vibration
    sonic crystal
    Opis:
    Sound insulation of the finite double-panel structure (DPS) inserted with a cylindrical shell array is investigated by varying the sound incidence direction to improve its applicability. The effects of the vibro-acoustic characteristics of its constituents on the sound transmission loss (STL) are estimated in one-third octave bands from 20 Hz to 5 kHz for different incidence conditions. It shows that the first acoustic mode in the direction parallel to two panels (longitudinal modes) produces both the sudden variation of sound insulation with frequency and a large dependency on the incidence angle. Mineral wools are placed on two boundaries perpendicular to the panels, and the sound insulation is explored for different thicknesses of the porous materials. An absorbent layer with a certain thickness (more than 30 mm in our work) sufficiently eliminates the longitudinal mode, resulting in the improvement in the sound insulation by more than 15 dB and the decrease of its large variation with incidence direction. STLs with varying shell thicknesses are also assessed. It shows that the natural vibrations of the thin shells can give an enhancement in sound insulation by more than 10 dB in the frequency range of 1600–3700 Hz, corresponding to constructive interference.
    Źródło:
    Archives of Acoustics; 2023, 48, 3; 381-388
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Broadening Low-Frequency Band Gap of Double-Panel Structure Using Locally Resonant Sonic Crystal Comprised of Slot-Type Helmholtz Resonators
    Autorzy:
    Kim, Myong-Jin
    Rim, Chun-Gil
    Won, Kyong-Su
    Powiązania:
    https://bibliotekanauki.pl/articles/1953478.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    sound transmission loss
    locally resonant sonic crystal
    double-panel structure
    sound insulation
    Opis:
    An approach is presented to form and broaden the low-frequency band gap of the double panel structure (DPS) by using a locally resonant sonic crystal (LRSC) in this work. The LRSC is made of cylindrical Helmholtz resonators arranged on square lattice. Their designs are similar to a slot-type resonator, but have different depths of slot. Elongating the slit neck inward and distributing the depths of slots produce a broad local resonant band gap at low frequencies: an average insertion loss (IL) of 10.9 dB covering 520 Hz to 1160 Hz with a LRSC of 12 cm width. Next, the effect of porous material filled into the resonators on the local resonant band gap is evaluated. It is shown that filling of porous material into the resonators decreases the height and width of the local resonant band gap. Finally, the transmission losses (TLs) through the DPS with LRSC are calculated as a function of the incident angle of the sound wave for LRSC embedded in porous material and not. The results show that the porous material can be significantly reduce the incident angle dependency of TL through the DPS with LRSC.
    Źródło:
    Archives of Acoustics; 2021, 46, 2; 335-340
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on the Performance Optimization of Turbulent Self-Noise Suppression and Sound Transmission of Acoustic Windows Made from Functionally Graded Material
    Autorzy:
    Li, Bing
    Zhou, Fu-Lin
    Fan, Jun
    Wang, Bin
    Tan, Liwen
    Powiązania:
    https://bibliotekanauki.pl/articles/31339793.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    functionally graded material
    acoustic window
    turbulent self-noise
    sound transmission loss
    optimization
    Opis:
    For a simplified sonar dome model, an optimization method for internal gradients of functionally graded material (FGM) acoustic windows is proposed in this paper. This method can be used to design optimized FGM acoustic windows with better turbulent self-noise suppression and sound transmission performances. A theoretical model of FGM acoustic windows to evaluate the reduction of self-noise caused by the turbulent boundary layer (TBL) pulsating pressure and the sound transmission loss (STL) is derived through the double Fourier transform and the wavenumber frequency spectrum analysis, respectively, based on the transfer matrix idea and the classical elastic theory. The accuracy of the theory is verified by the finite element results of COMSOL Multiphysics. Utilizing the genetic algorithm (GA) and taking the monotonic gradient as the constraint condition, the internal gradient optimization method of FGM acoustic windows obtains the optimization variables in the Bernstein polynomial when the optimization objective is minimized by iterating the optimization variables in the deviation function represented by the Bernstein polynomial that is introduced in the gradient function. The STL, the turbulent self-noise reduction or a weighting function of the STL and turbulent self-noise reduction of FGM acoustic windows is chosen as the optimization objective. The optimization calculation of the sound transmission or turbulent self-noise suppression performances is carried out for the FRP-rubber FGM (FGM with fiber reinforced plastic (FRP) as the substrate material and rubber as the top material) acoustic window. The optimized results show that both the sound transmission and turbulent self-noise suppression performance are effectively improved, which verifies the effectiveness of the optimization method. Finally, the mechanism of the sound transmission and self-noise suppression characteristics before and after optimization are explained and analyzed based on the equivalent model of graded materials. The research results of this paper provide a reference value for the future design of FGM acoustic windows for sonar domes.
    Źródło:
    Archives of Acoustics; 2023, 48, 4; 475-495
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analytical and Computational Acoustic Modelling of Side Outlet Muffler and Its Extension in the Modelling of Tapered Side Outlet Muffler
    Autorzy:
    Vishwakarma, Sandeep Kumar
    Pawar, Jayappa
    Powiązania:
    https://bibliotekanauki.pl/articles/31339955.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    1-D analysis
    finite element analysis
    FEA
    sound pressure level
    transfer matrix
    transmission loss
    Opis:
    Mufflers are popular in the suppression of noise levels coming from various machinery. The most common parameters for the evaluation of the performance of mufflers are transmission loss, noise level, and insertion loss. The transmission loss is evaluated for tapered side outlet muffler using finite element analysis without considering the fluid-structure interaction. This study includes analytical modelling and acoustic modelling of the side outlet muffler and transmission loss is in excellent agreement with the reference paper. The feasibility of the acoustic model is also verified with the experimental work on simple expansion chamber muffler. The same finite element analysis is extended for the tapered side outlet muffler. The transmission loss of the tapered side outlet muffler in the given frequency range is found 8.96 dB better than the side outlet muffler. The acoustic pressure level and sound pressure level contours for the tapered side outlet muffler give a clear picture of wave propagation inside the muffler. The effect of the cut-off frequency on the transmission loss of the tapered side outlet muffler can be seen from the contours. This study can be helpful in the determination of the performance of the mufflers in terms of transmission loss, the performance of mufflers above cut-off frequency, and design improvements in the muffler to avoid the higher-order modes of the sound wave.
    Źródło:
    Archives of Acoustics; 2022, 47, 4; 491-499
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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