具加勁複合材料結構板之聲傳研究

Abstract

本文主要是研究以不同加勁設計之複合材料結構板為揚聲板對聲傳行為的影響，以期設計出具有足夠剛性之具加勁複合材料結構板來避免聲壓值的起伏落差，而呈現出平滑之聲壓曲線。 透過四種加勁設計之複合材料結構板及未做加勁設計之平板的比較，探討其聲壓曲線之差異以及差異產生的原因，來研究如何做出能有效提高平板結構剛性之加勁設計。 在理論分析上，利用有限元素軟體ANSYS建構以不同加勁複合材料結構板為揚聲板的揚聲器系統分析模型，將由實驗測得之系統參數，如懸邊彈簧常數、激振器之彈波彈簧常數、音圈出力以及系統阻尼等，代入ANSYS模型中分析運算，便可得到振動板上各點之振幅與相角，再將得到之振幅與相角代入聲壓計算程式中，以模擬不同加勁複合材料結構板之揚聲器系統的聲傳行為，經由模擬結果與MLSSA聲壓頻譜儀測得之聲壓曲線的比對，而找出造成聲壓值起伏的原因並且加以改善，在本文中對於實驗結果與理論模擬之間誤差的產生原因也將予以討論說明。

The effects on sound radiation of composite panels with different stiffened designs are studied in this thesis. This study is used to design the stiffened composite panels with enough stiffness which can avoid the fluctuation of sound pressure. By investigating the differences among the behaviors of sound pressure responses of four types of stiffened plates and an unstiffened one, we obtain a structural design which can effectively modify the stiffness of a plate structure and its sound radiation behavior. For theoretical analysis, the simulation models of radiating panels with different designs of stiffeners were constructed using the software ANSYS. The amplitudes and the phases of these panels were obtained from the analyses of the simulation models using given system parameters such as spring constants of suspension and damper, the thrust of the voice coil and the damping ratio of the loudspeaker system, which were measured from experiments. Then, we use the amplitudes and the phases in the program of calculation of sound pressure level to simulate the behaviors of sound radiation of the loudspeakers. Through the comparison between the curves of sound pressure response measured by the sound measurement system MLSSA and the ones simulated by computer, we can find out the reason causing the drops in sound pressure curves and the direction to improve the loudspeaker system further. Finally, the discrepancies between the results of experiment and these of simulation were discussed.