The Journal of the INCE of Japan
Online ISSN : 1883-7506
Print ISSN : 0386-8761
Volume 33 , Issue 6
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Dissertation—Contribution
  • Masanori Nakaoka, Kunihiko Ishihara
    2009 Volume 33 Issue 6 Pages 446-457
    Published: December 01, 2009
    Released: January 29, 2020
    JOURNALS FREE ACCESS

    For the purpose of utilizing the waste of bark as sound absorbing material, sound absorption properties and an estimation method of normal incidence absorption coefficient were investigated for the bark fiber on the assumption that the bark was crashed and compressed at a constant bulk density. First of all, the misfits appeared between calculated values and measured values after estimating by using the existing absorption model for fibrous material. Therefore, the approximation method of Delany-Bazley model was applied to the characteristic impedance and the propagation constant that were measured by the two-thickness method for reflecting measured values to the estimation formula. Next, another estimate formula, that could calculate the flow resistivity from the bulk density, was given from the relationship between the both measured values. Eventually, the most suitable compressing condition, that the bark fiber could behave good performance, was identified from simulations by using those optimized estimation formulas for the bark fiber.

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