本論文中以PVDF壓電薄膜自製線聚焦式超聲波換能器，並根據此換能器構成一套散焦量測系統，具有5MHz~20MHz的寬頻量測能力，由於換能器之線聚焦特性，可針對非等向性試件量測不同方向的波速，包括表面波與平板的蘭姆波，尤其可以得到相當準確的蘭姆波頻散曲線。
藉由此系統，本文探討受應力作用及不同程度塑性變形之平板試片的聲彈性效應(Acoustoelastic Effect)與聲塑性效應(Acoustoplastic Effect)，量測平板試片之藍姆波的頻散曲線，並由實驗所獲得的頻散曲線變化，了解藍姆波與應力應變之間的聲彈性效應與聲塑性效應。
文中另一個研究重點為非等向性鈮酸鋰(LiNbO3)壓電板受導電溶液負載時蘭姆波頻散曲線的變化情形，實驗量測不同波傳方向與不同溶液導電度下的藍姆波頻散曲線，討論頻散曲線變化趨勢及各角度對導電度的靈敏性。

In this thesis, line-focus PVDF focusing transducer and its measurement system operating from 5 MHz to 20 MHz have been applied to the measurements of Lamb wave velocities and dispersion curves. Since the transducer is line-focused, the wave velocity measurement can be along any specific direction of anisotropic samples. Good accuracy in velocity measurements and low cost make the transducer and the system a useful tool for ultrasonic non-destructive evaluation.
This thesis first investigates the acoustoelastic and acoustoplastic effects of Lamb waves in an isotropic plate. The Lamb wave dispersion curves for thin plates subjected to several different elastic strains and plastic deformation are experimentally measured. The measurement results show that the wave velocities are indeed influenced by the elastic and plastic deformation. However, the trends for elastic and plastic cases are quite different.
Furthermore, the influence of conducting fluid on the Lamb wave propagation characteristics of a piezoelectric plated is investigated. A X-cut LiNbO3 thin plate is used as the sample. The measurement data indicates a systematic change in dispersion curves when the piezoelectric plate is immersed in a conductive fluid with different conductivity. The angular dependence of the conductive fluid-loading effect is also studied.

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