複合材料三明治板之振動與聲射研究

Abstract

本文的目的在討論複合材料三明治板之振動特性，並且探討複合材料三明治板在不同尺寸時，各個激振頻率下的聲壓曲線變化。 在理論部份，本篇論文使用多層一階剪變形理論來建立複合材料三明治板之力學關係，以Rayleigh-Ritz Method求解複合材料三明治板的自然頻率。在聲壓方面，由有限元素軟體建立複合材料三明治板的模型進行頻率響應分析，將頻率響應分析所得到的相關數值代入聲壓公式做計算，繪製出各個激振頻率的聲壓趨勢曲線。由理論分析了解在複合材料三明治板不同尺寸下，聲壓趨勢曲線的變化。 在實驗部份，先量測複合材料三明治板的自然頻率與理論驗證，接著將激振器放置在複合材料三明治板中央量測各個激振頻率下所產生的聲壓趨勢曲線，將實驗所得到的結果與理論分析作比較，並討論如何在低頻中獲得良好的聲壓曲線。

In this thesis, vibration characteristics of laminated composite sandwich plates are studied via experimental and theoretical approaches. Sound pressure responses of laminated composite sandwich plates with different vibration characteristics are also studied experimentally and theoretically. In the theoretical study, the vibration analysis of laminated composite sandwich plates is achieved via the use of the Rayliegh-Ritz Method. In sound pressure analysis, the modal and harmonic analyses of laminated plates are performed using the finite element code ANSYS. The amplitude and phase angle obtained from the harmonic analysis together with sound pressure equation are used to construct the sound pressure level (SPL) curves. The SPL curves change for different sizes of laminated composite sandwich plates in the sound pressure analysis. In the experiment approach, above all, the measured natural frequencies of laminated composite sandwich plates are used to verify the theoretical results. Furthermore, sound pressure responses of different sandwich plates are measured and used to verify the theoretical results. The comparison between the experimental and theoretical results shows that the present method can produce satisfactory results for both natural frequencies and SPL curves.