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    Wyświetlanie 1-4 z 4
    Tytuł:
    Assessment of sound absorbing properties of composite made of recycling materials
    Autorzy:
    Gaj, Patryk
    Kopania, Joanna
    Wójciak, Kamil
    Bogusławski, Grzegorz
    Powiązania:
    https://bibliotekanauki.pl/articles/128049.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    sound absorbing materials
    recycling
    sound absorption coefficient
    composite materials
    materiały dźwiękochłonne
    recykling
    współczynnik pochłaniania dźwięku
    materiały kompozytowe
    Opis:
    In modern world we are searching methods to reuse most of industrial disposals produced during manufacturing. Some kinds of materials, like scraps from acoustic foam, however are not so easily utilized using recycling methods for its primary usage. Disposals produced during the manufacturing process can be compressed and reused as sound absorbing material. The purpose of this article is to examine sound absorbing properties of material made of acoustic foam disposals and compare it with sound protection materials, which are commonly used. Sound absorbing damping were tested using Kundt’s tube and reverberation room examination method. Tests were carried out according to standard PN-EN ISO 354:2005, for reverberation room examination, and according to Bruel&Kjaer electronic instruments technical manual for Kundt’s tube examination.
    Źródło:
    Vibrations in Physical Systems; 2019, 30, 1; 1-7
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental tests of the acoustic properties of sound-absorbing linings and cores of layered baffles
    Autorzy:
    Kosała, Krzysztof
    Powiązania:
    https://bibliotekanauki.pl/articles/2146647.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    sound transmission loss
    sound absorption coefficient
    insertion loss
    baffles
    mineral wool
    izolacyjność akustyczna od dźwięków powietrznych
    współczynnik pochłaniania dźwięku
    tłumienie przepustowe
    przegrody
    wełna mineralna
    Opis:
    The article presents the results of research on the acoustic properties of materials used as sound-absorbing linings and cores in baffles of anti-noise protection. Using an impedance tube the spectral characteristics of the normal incidence sound absorption and sound transmission loss indices of 12 specimens of mineral wool with different density and thickness were determined. From these characteristics, the single-number weighted sound absorption coefficient αw and the sound reduction index Rw were calculated. To calculate the value of the Rw index on the basis of surface mass of the mineral wool specimen, a new formula was proposed. The insertion loss of an acoustic enclosure with one, two and three-layer walls with dimensions of 0.7×0.7 m, containing mineral wool, was determined. The best efficiency was achieved for the enclosure made of walls of layers: mineral wool, placed on the sound source side, steel plate and aluminium plate.
    Źródło:
    Vibrations in Physical Systems; 2021, 32, 1; art. no. 2021107
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental verification of similarity criteria for sound absorption of simple metamaterials
    Autorzy:
    Chojak, Aleksandra
    Powiązania:
    https://bibliotekanauki.pl/articles/2202415.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    scale model
    scale model test
    MES
    transfer matrix method
    TMM
    sound absorption coefficient
    model redukcyjny
    test modelu redukcyjnego
    metoda macierzy przejścia
    współczynnik pochłaniania dźwięku
    Opis:
    The paper concerns the dimensional analysis of simple acoustic metamaterials and its experimental verification in a computer model. Due to their decreased thickness possible because of the thermoviscous losses and sound dispersion that occur in acoustic metamaterials, such structures are gaining popularity, both as sound absorbers and diffusers. This implies the need to find their equivalents to be used at scale - both for modeling interiors with metamaterials and developing more complicated structures. The paper discusses the dimensional analysis performed for a generalized unit cell of a metamaterial with a resonator. The dimensional analysis shows the need for scaling both the geometrical dimensions of the structure and the parameters of the medium - air. The dimensional analysis was derived based on the transfer matrix method and was proven correct with the finite element method model. The paper also discusses the consequences of neglecting the air criteria, which are impossible to be fulfilled. This opens the question of finding new criterial numbers allowing the correct reflection of acoustic metamaterials at scale.
    Źródło:
    Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022211
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparative analysis of the acoustic properties of granular materials determined with the use of impedance tube
    Autorzy:
    Kosała, Krzysztof
    Powiązania:
    https://bibliotekanauki.pl/articles/24202011.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    granular materials
    sound absorption coefficient
    sound transmission loss
    materiały ziarniste
    współczynnik pochłaniania dźwięków
    strata transmisji dźwięku
    Opis:
    The results of acoustic property tests for six types of granular materials: perlite, vermiculite, active coconut carbon, rubber granulates, pumice and wood chips, which can be used in noise protection structures, are shown in the article. The characteristics of the normal incidence sound absorption coefficient and the normal incidence sound transmission loss for material specimens with seven thicknesses in the range of 10-100 mm were determined based on the results of experimental tests carried out with the use of an impedance tube. The relationships between the first resonant absorption frequencies and the thicknesses of material specimens were determined. Single-number indices for the tested materials, in the form of the weighted sound absorption coefficients, were determined. Subsequently, dependencies of these indices on the surface mass of the tested materials were determined. The research showed that three materials, perlite, vermiculite and active coconut carbon, were distinguished among the examined granules with the best sound-absorbing and sound-insulating properties. Active coconut carbon had the best sound-insulating properties among the granular materials tested.
    Źródło:
    Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022321
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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