具加勁矩形複合材料揚聲器的振動模擬及聲傳研究

Abstract

本文主要研究長形高功率揚聲器之加勁方式對聲音傳遞的影響。以相同面積下考量下，長形的揚聲器比圓形的揚聲器要來的容易利用空間。但對長形揚聲器而言，在中音域會產生一聲壓落差，影響聲傳表現，因此本文透過適當的加勁方式增加揚聲板的剛性，以改善揚聲器聲壓落差問題。本文可為二部分，第一部分，以”Rayleigh-Ritz Method”與”有限元素分析軟體ANSYS”互相驗證揚聲器之自然頻率與聲壓曲線，再以實驗驗證ANSYS模型，建立一套完整的分析方法。第二部分，利用”有限元素分析軟體ANSYS”，分析揚聲器較適當的加勁方式及分析較理想的揚聲板以及碳纖材料的常數，以達到延後中音谷頻率與提升揚聲板剛性。

This paper is focused on the sound radiation behavior of stiffened sound radiation panels for flat-panel loudspeaker. If the sound radiation panel is not properly design, it is easy for a flat-panel speaker to have a significant sound pressure drop in the mid-frequency range, which may affect the sound quality of the speaker. To suppress or even eliminate the sound pressure drop, this thesis attempts to enhance the rigidity of the plate by using an appropriate stiffening method. There are two parts in this thesis. In the first part, a Rayleigh-Ritz Method is constructed to analyze the sound radiation behavior of stiffened sound radiation panels. The results obtained using the proposed Rayleigh-Ritz Method are compared with those obtained from the finite element software ANSYS. It has been shown that the natural frequencies and the sound pressure level (SPL) curves produced by the proposed method are in good agreement with those produced by ANSYS or experiments. In the second part, ANSYS is used to find the appropriate stiffening pattern for designing the sound radiation panel and the ideal material constants of the panel so that the major sound pressure drop in the mid-frequency range can be suppressed.