吸,隔音材料性能之理論探討

A Theoretical Study on the Characteristics of Acoustical Matericals

曾一航(TSENG, I-hang)

指導教授 ： 王昭男

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01085

摘要

本文探討多孔材與隔音板組合之吸音與隔音效果。文中利用Biot彈性理論推導聲音在多孔材中之波動方程，及Allard所建立聲波在單層材料中傳遞時的傳輸矩陣，即可求得材料上任一點的壓力與速度。再將材料與材料間的連續邊界條件引入，如：多孔材、隔音板、空氣、水彼此間之邊界連續條件整理成一方陣，計算出聲波入射此組合材料之吸音率與穿透損失。
文章首先介紹了多孔材料的波傳理論以及整體分析的架構，導證多孔材料內可有兩個壓縮波以及一個剪力波存在。並將Allard建立的轉換矩陣應用在計算材料吸音率及穿透損失。接著，將以往學界所發表的文獻和做過的實驗，與理論程式互相比對，以印證理論程式的正確性。
再來則是分別就空氣中與水中探討材料的吸音與隔音性能。在空氣中的吸音材料，選用了玻璃棉及PU泡棉，而水中的吸音材料則選用橡膠材料及其複合物；隔音板則選用鋼材，因為其剛性強、不易形變，材料本身及其參數隨手可得。在空氣中吸音結構方面，將多孔材料做複合層的堆疊，可以有良好的吸音效果，而隔音方面，則是選用中間夾多孔材料的三明治結構能達到輕量化、經濟的目的。在水中吸音結構方面，模擬了潛艦與海洋環境的關係，目的是將敵艦的探測聲納吸收。在水中隔音方面，模擬潛艦聲納鼓結構，目的是在於儘量降低穿透損失，以利接收我方所打出的探測聲納。
最後，分別就空氣中以及水中的材料參數，分門別類的觀察其對吸音與隔音的影響。在空氣中所討論的參數，有多孔材密度、多孔材厚度、鋼材厚度。在水中所討論的參數，有多孔材孔隙率、孔隙尺寸、多孔材厚度、鋼材厚度、聲波入射角度。

關鍵字

組合結構 ； 多孔材料 ； 吸音 ； 隔音

並列摘要

The objective of this research was to discuss the absorption coefficient and transmission loss of porous materials lined with partitions. In the thesis, we used Biot’s theory to derive the equations of waves propagating in a fluid-saturated porous material and combined with the transfer matrix of porous materials introduced by Allard to evaluate the pressure and speed of any given point on the material. If we furthermore put the boundary conditions between various materials into a matrix, we will then be able to evaluate the absorption coefficient and transmission loss of multi-layers of materials.

At first, we introduced the wave propagation of porous materials and find that there could be two compression waves and one shear wave existing in porous materials. We then applied the transfer matrix introduced by Allard to evaluate the absorption coefficient and the transmission loss of the materials and also compared the results to the previous lectures, including experiments and theoretical analysis, to verify the accuracy of the present method.

Then the absorption coefficient and transmission loss of materials in air and in water was discussed respectively. For the sound absorption investigation, glass wool and PU foam on air and rubber in water were studied. It can be found that the sound absorption coefficient improved obviously when porous materials are put in layer with high density one in front of the sound source. For sound insulation in air, we focus on the sandwich structures that are formed by steels lined with porous material. The purpose is to create a light weight and high efficient insulation material. In the absorption of sound in the water, we simulated the conditions of submarines in naval environments in order to absorb the sounds of the sonar system of enemy ships. In the sound insulation in the water, we simulated sono-tones of submarines to lay efforts on lowering the loss of transmission.

Finally, the parameters, such as density, thickness of porous media, thickness of steel of each material in air and porosity, pore size, thickness of porous materials, thickness of steel and incident angles in water were investigated and also the influence on the sound absorption and insulation were discussed.

並列關鍵字

Biot theoretical ； absorption coefficient ； acoustical matericals

參考文獻

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