揚聲平板之最佳設計參數研究

Abstract

本文在討論長方形振動板之揚聲器各項參數對聲壓曲線的影響，其中包括了振動板的長寬比值、振動板結構、音圈直徑、以及系統阻尼等，首先以有限元素分析軟體ANSYS利用簡諧激震分析來模擬揚聲平板的振動行為，並以實驗來證明其可行性及正確性；之後以驗證過的ANSYS模型為主，改變各種參數，探討其與聲壓曲線之間的關係，找出設計長方形揚聲平板之最佳長寬比值範圍，及適合的音圈直徑，由分析得知，以純巴沙木(E1/E2=67.273) 、發泡板(E1/E2=1) 、碳纖三明治板(E1/E2=18.322)而言，長寬比值介於1.6~1.9之間為其最佳長寬比範圍，此外針對不在此長寬比值範圍內的振動板，以碳纖複材加強板子結構的方法，達到改善其聲壓曲線的目標，使長方型振動板之揚聲器能產生更完美的聲音品質。

The influence of each parameter of rectangular pane1 on its SPL curve is discussed, including the panel’s aspect ratio and structure, the coil diameter, and the system’s damping. The harmonic analysis of the panel is performed using the FE software ANSYS. Experiments are performed to insure its correctness. Then, based on the FE model, the displacement response spectrum of the panel determined in the FEA is used to calculate the sound pressure radiated from the vibrating panel. The SPL curve of the panel is constructed in the sound radiation study of the panel. The influence of the changes of the parameters on SPL curve is studied, so as to find the optimal aspect ratio range of the rectangular panel. In the sensitivity analysis, it has been shown that the optimal aspect ratios for panels mode of pure balsa(E1/E2=67.273), foaming panel(E1/E2=1), carbon sandwich panel(E1/E2=18.322) are in the range from 1.6 to 1.9. Besides, for panels with aspect ratios out of the above specified range, it has been shown that use of carbon composite reinforced panel can make the loudspeaker produce better and pleasing sound.