多組態聲子晶體之聲學二極體於可調控單向聲波傳輸

Abstract

本研究中提出一多組態之可調控式聲學二極體，該結構是由兩種尺寸之金屬鋁棒所組成，本研究使用方法：其中數值模擬部分使用有元素法分析藉由商用軟體COMSOL Multiphysics 5.0，包含特徵頻率計算與聲壓場計算，而實驗部分則是在無響室中進行聲學實驗量測該結構之穿透損失，由上述兩方法所得之實驗與模擬結果呈現了良好之吻合程度。進一步分析下列項目：各組態下之調控性能與比較、大小角度轉動所帶來之效益、容許小角度調控誤差以及聲學薄膜之設計討論。本研究之設計將改善現有之聲學二極體存在之問題，並透過薄膜設計將有希望可以應用於非破壞檢測以及醫用超聲波，舉凡聲學成像清晰與避免聲學儀器損壞。

In this research, the sonic-crystal-based tunable acoustic diode is proposed. This proposed acoustic diode can tune working frequency ranges by transforming its configurations. The acoustic characteristics of nonlinear transmission in proposed structure have favorable agreement between numerical results and experimental results. For these results, all the numerical results are calculated by using COMSOL Multiphysics 5.0 and the experiment results are measured in anechoic chamber. Moreover, effects of rotating angles and allowable errors of rotating angles are discussed to indicate that the proposed structure is a promising acoustic device for applications in the future. The proposed structure is designed as an acoustic membrane and this membrane shows its favorable tunability for controlling unidirectional transmission. All analyses for the proposed structure are beneficial to acoustic applications. The proposed acoustic membrane can alleviate the problems of acoustic imaging and non-destructive testing, and keep acoustic device from damages.