三明治蜂巢板之隔音性能

Abstract

本文目的在探討三明治蜂巢板之隔音性能。首先，將三明治板視為由多層介質所組合而成之複合板，而中間的芯材則為一彈性多孔材料，之後再利用Biot彈性理論分析聲音於多孔材中的傳播情形，並建立聲波在平板兩點間傳遞之轉換矩陣，最後藉由這些轉換矩陣來計算三明治蜂巢板之隔音性能。 為了驗證本文之理論，引用四組由Moore所量測之三明治複合板的數據，比較實驗數據與本文理論計算所得之數據，除Panel D因其結構與理論之基本假設不符外，其餘計算的結果皆大致符合，可證明本文理論之可行性， 以此理論作數值分析，藉由不同案例去探討芯材之相關參數，如厚度、密度與蜂巢孔徑，對隔音性能的影響。理論分析後發現，芯材厚度的變化會改變吻合效應所發生的頻率，進而影響整體之隔音性能。而芯材密度的改變亦會有類似的影響，吻合頻率會隨著芯材密度的減小而往低頻處移動，待密度超過某一定值後，此時吻合效應所發生的頻率則趨近一固定值。最後，由理論分析可知蜂巢孔徑對三明治板之穿透損失的影響甚微。

The purpose of this research is to discuss the sound insulation characteristics of honeycomb sandwich panel. At first, the sandwich panel is made of layered media and the center core was regarded as an elastic porous material. Thus, the Biot theory could be employed to analyze the waves propagated in fluid saturated porous material. The transfer matrix for waves propagated between two ends of the sandwich panel was established. The combination of these related matrices can be applied to evaluate the transmission loss. To order to verify the present method, four sandwich panels which were measured by Moore are analyzed. The comparison of the transmission loss between experimental data and numerical predictions is reliable except the Panel D. In the case of Panel D, the fundamental settings are different from present method in this thesis. Using the present method, several cases are set up to investigate related parameters of cores, such as thickness, density and cell size. The numerical results show that the coincident frequency will change with different thickness of the core and this variance in frequency will influence the sound insulation of the panel. In addition, the effect of core density is similar to the effect of core thickness. The coincident frequency will decrease with the increase of the core density until the core density increase to exceed certain limit. At the time, the coincidence will occur in the same frequency. Finally, cell size of the core doesn’t influence the transmission loss of sandwich panels.