本論文主要探討在聲子晶體平板上之蘭姆波波傳分析與實驗量測，共設計三種不同結構聲子晶體平板，分別為圓洞型、圓盲孔型、橢圓盲孔型，首先分別對其進行有限元素模擬，計算頻帶結構與全波模擬穿透率分析，觀察聲子晶體的波傳特性，最後透過實驗量測進行比較與驗證。
有限元素模擬部分，首先觀察均質平板之波傳特性，並藉由不同蘭姆波傳遞模態的位移場特徵對其進行分類，將三維模擬中不屬於蘭姆波模態之頻散曲線移除，以降低分析頻帶結構之難度。接著分別探討在圓洞型、圓盲孔型、橢圓盲孔型聲子晶體平板上之波傳行為，同樣將各頻帶結構做模態篩選與過濾後，再經由頻帶結構圖中觀察沒有頻散曲線通過的區域，該段區域即屬於聲子晶體之能隙，最後再透過全波模擬施打特定模態的蘭姆波並計算其穿透率，用於佐證頻帶結構圖中所觀察到的能隙現象。
實驗部分共分為兩種實驗方法，第一種方法為超聲波顯微鏡量測實驗，使用PVDF壓電薄膜製作的探頭，針對圓盲孔與橢圓盲孔結構進行量測，再利用頻域量測法對實驗數據進行後處理後可將實驗結果轉換為傳遞波之頻帶結構圖。第二種方法為陶瓷壓電片超聲波換能器實驗，針對圓洞型結構進行量測，利用壓電片的幾何尺寸控制蘭姆波之中心作用頻率，再將作用頻率設計在聲子晶體能隙上進行實驗量測，觀察壓電訊號在能隙中衰減之現象。以上兩部分實驗皆會與有限元素模擬部分進行結果比較。

In this study, we discuss the behaviors of Lamb wave propagating on the plate with periodic structures, which are so-called phononic crystal plates. Three kinds of phononic crystal structures are considered, which are named “round hole-type”, “round blind hole-type” and “elliptic blind hole-type”, respectively. We employ finite element method to investigate the special wave propagating phenomena of the structure, such as band gaps and changes of wave velocity, then we utilize two experimental methods, which are based on a PVDF line-focus transducer and PZT transducer, to investigate the samples with these periodic structures, and compare the experimental results with numerical results.

In the part of numerical simulation, we first observe the wave propagation characteristics of homogeneous plates and classify it by the characteristics of the displacement field of different Lamb wave propagation modes. Then we discuss the band structures of the plates with three kinds of phononic crystals, the band structures show the absence of specific Lamb wave modes dispersion curves in some frequency ranges, namely the band gaps of Lamb wave, and the mechanisms that lead to band gaps are discussed.

In the part of experimental measurement, we first use the experiment system with PVDF line-focus transducer to measure the “blind hole-type” phononic crystal structures and then utilize the other experiment system with PZT transducer to measure the “hole-type” phononic crystal structures. The decrease of wave velocity and band gaps can be found in measurement results, which are consistent with simulation results. Based on this research, we can build a complete process of the analysis of phononic crystal plates.

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