以傳遞矩陣法及有限元素法分析水下混合型消聲結構

Abstract

本文以含有空腔的消聲結構為基礎，提出了一種新型的混合型水下消聲結構，其使用微孔平板和粘彈性材料製造，在不增加結構厚度之情況，提升了低頻區域的聲學吸收效果。理論方面由均質等效之理論模型和傳遞矩陣方法，來評估所提出的非均質消聲結構，同時將理論與有限元素模擬結果作相互驗證，並在有限元素軟體內探討不同頻域所涉及的消聲機制。在聲學性能方面此混合型消聲結構與傳統吸聲器相比獲得大幅的改善，其在2-10kHz的頻域範圍內具有0.8以上的吸聲係數，最後提出了實際於水下應用之結構，說明本文所提出的設計具有作為水下消聲結構應用之潛力。

Based on the traditional anechoic coatings with cavities, this paper proposes a new type of hybrid underwater anechoic coating without increasing the thickness of the coating, which is made of micro-perforated plates and viscoelastic substrate. And this anechoic coating achieves good absorption performance in the low-frequency range. In theory, applications of the concept for homogenized equivalent layer and integrated transfer matrix method to evaluate the sound absorption performance of this nonhomogeneous underwater anechoic coating. Then comparisons of the theoretical model and finite element method to validate that present approach. The results reveal two absorption peaks of the hybrid anechoic coatings appear since the different physical mechanisms. The acoustic performance of the hybrid anechoic coating has been greatly improved compared with the traditional sound absorber. Meanwhile, it is shown that the sound absorption coefficient of structure is achieves 0.8 in the frequency range 2 kHz-10 kHz, which indicates that the design proposed in this paper has the potential to be used as an underwater sound absorption structure.