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Title page for etd-0715104-234153


URN etd-0715104-234153 Statistics This thesis had been viewed 2037 times. Download 9 times.
Author Chih-Wei Lin
Author's Email Address No Public.
Department Mechanical Engineering
Year 2003 Semester 2
Degree Master Type of Document Master's Thesis
Language English Page Count 120
Title Acoustic Absorption Characteristics of Composite Perforated plates with Porous Material
Keyword
  • tuning tube
  • standing wave tube
  • composite perforated plates
  • air gap
  • absorption coefficient
  • absorption coefficient
  • air gap
  • composite perforated plates
  • standing wave tube
  • tuning tube
  • Abstract ABSTRACT
    This study aims to discuss the sound absorption properties of the composite perforated plate and the porous asbestos fiber. When the sound absorption properties of a perforated plate, together with the attached porous asbestos fiber, and the rear air gap have been altered, it will affect the sound-absorbing rate, as well as how the sound absorption capacity will be increased in low frequency bandwidth.
    Conclusions drawn from latest research results:
    The four-point conclusions listed below were drawn from the experiment on the sound-absorbing characteristic of single level perforated plates and porous asbestos fiber materials.
    (1) (i) When the parameters of the sound absorption of perforated plates are equal, the sound absorption rate of the perforated wood plates is better than that of a perforated acrylic board.
    (ii) When the sheet materials of perforated plates are the same, the bore diameter size and depth of the bore diameter will affect the absorption qualities within the perforated plates sound absorption parameter. When the bore diameter is smaller, the sound absorption rate obtained is more favorable. Likewise, when bore diameter depth is deeper, the sound absorption rate obtained is more favorable.
    (iii) When an asbestos fiber material is attached to the perforated plate, the sound absorption rate is evidently better compared to a perforated plate without the asbestos fiber material.
    (iv) When the rear air gap of the perforated plate is bigger, the sound absorption rate likewise increases. Nevertheless, to achieve a more effective sound absorption rate, attachment of an asbestos fiber material is still required.
    (2) The experiment result reveals that the efficiency of the sound absorption properties of the composite perforated plate and the porous asbestos fiber material, when applied on different bandwidths, shows corresponding merits and defects. To aim at increasing its strong points, the sound absorption capacity of the bandwidth is required.
    (3) The method in improving the sound absorption rate of low frequency
    bandwidth is to use a tuning tube and a perforated tuning tube on the
    sheet materials. Then using a perforated wood plate under the same
    conditions, a series of comparison was done. Thus, it was discovered
    that the sound absorption rate of the low frequency bandwidth clearly
    increased.
    Advisor Committee
  • Ying-Jun Chang - advisor
  • Long-Jyi Yeh - co-chair
  • Shih-Pin Liaw - co-chair
  • Files indicate in-campus access only
    Date of Defense 2004-06-24 Date of Submission 2004-07-15


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