結構振動所造成之聲輻射研究

Abstract

本篇論文主要探討結構振動於空氣場中的聲輻射(Sound Radiation)機制。首先，在簡支邊界條件下，我們討論兩種結構(圓板與矩形板)的聲音強度與輻射效率之特性。接著，我們將矩形板簡化成一維的細長板型式，並在相同聲輻射理論下，研究線性與非線性細長板的聲輻射機制。 在邊界條件皆為簡支邊界的情況下，我們將線性與非線性細長板的聲壓與聲音強度作分析，討論兩者在不同模態下的影響。接著歸納出於空氣場中，聲音強度在不同距離下的差異。最後，我們討論非線性細長板中的阻尼、勁度與擾動係數對其聲壓產生的影響並加以比較。

This paper focuses on the mechanism of sound radiation from vibrating structures in the air field. First, under a simply supported boundary condition, we discuss the characteristics of sound intensity and radiation efficiency for two types of structures (circular plate and rectangular plate). Second, we simplify a two-dimensional rectangular plate as a one-dimensional thin plate. Together with the preceding sound radiation theorem, the mechinical mechanism of sound radiation corresponding to the linear and nonlinear thin plate will be investigated. A analysis of sound pressure and intensity indueced by the vibrating linear and nonlinear thin plate with the simply supported boundary condition will be perfromed, and the influnece of different mode shapes be discussed. Then, induced sound intensities corresponding to distinct ranges in the air field will be also observed. Finally, the comparison of sound pressure will be executed by discussing the relevant factors of the nonlinear thin plate involving the damping, stiffness, and perturbation coefficient.