本論文利用無鏡頭式線聚焦PVDF換能器和散焦量測系統，量測圓柱曲面導波，包含沿著圓柱體或鍍層圓柱體圓周方向傳遞的圓柱表面波 (Rayleigh-like cylindrical surface waves)，與在薄壁圓管圓周方向傳遞的圓柱蘭姆波 (Cylindrical Lamb waves) 的頻散曲線。不同於一般平面體的散焦量測，在量測圓柱曲面的表面波與蘭姆波時，散焦造成的干涉相位與位置之間的改變是非線性的；因此，為了能夠利用V(f,z)散焦量測系統與波形分析法求得在不同頻率下的表面波波速，本論文引入一種新的交叉相關法 (Cross-Correlation method)，分析V(z)震盪曲線的干涉相位變化，以萃取得到在：(1)圓柱體表面或 (2)鍍層圓柱體表面傳播的圓柱表面波波速與 (3)薄壁管圓上傳遞的蘭姆波波速。針對這三種不同特性的試片，本論文以實驗量測得到圓柱體表面波與圓管蘭姆波的頻散曲線，並與理論計算的結果相比較，得到非常吻合與接近的結果。
此外，利用無鏡頭式線聚焦PVDF換能器和V(f,z)散焦量測系統，本論文研究彈性體中的聲彈性和聲塑性現象與行為。首先，利用單軸拉伸系統使待測物體產生不同程度的彈性變形，再量測沿著單軸拉伸方向與不同角度方向下的表面波波速與其變化，最後決定待測物的聲彈性係數。另外，同樣以單軸拉伸的方式在待測試片中產生永久形變，利用量測系統量測表面波的波速變化，根據波速變化評估與探討材料的聲塑性行為。此一方面的研究證明：無鏡頭式線聚焦PVDF換能器和V(f,z)散焦量測系統提供了一種非破壞性的檢測方式，檢測物體是否受力或有殘餘應力的產生。

Lens-less line-focused PVDF transducers and defocusing measurement method are applied to determine the dispersion curves of cylindrically guided waves, including Rayleigh-like cylindrical surface waves propagating along the circumferential direction of solid cylinders and layer-coated cylinders, as well as cylindrical Lamb waves on circular annuli. Conventional V(f,z) waveform processing method has been modified to cope with the non-linear relationship between the phase angle of wave interference and the defocusing distance. A cross correlation method is proposed to accurately extract the cylindrically guided wave velocity from measured data. Experiments have been carried out on: (1) stainless steel and glass cylinders, (2) Ni-coated stainless steel cylinders, and (3) cylindrically curved stainless steel sheets. The experimentally obtained dispersion curves are in very good agreement with their theoretical counterparts. Variation of cylindrically guided wave velocity due to the cylindrical curvature is quantitatively verified using this method.
Line-focused PVDF transducers and its V(f,z) defocusing measurement system are also applied to determine the acoustoelastic and acoustoplastic effects of deformed polymethylmeth-acrylate (PMMA) samples, as well as silicon steel samples with permanent deformation. Different levels of strain or permanent deformation are formed in PMMA and silicon steel samples. Large plastic deformation ranging from 5% to 30% is created in the silicon steel samples using uni-axial tensile loading. The velocity changes of surface acoustic waves under different strain or plastic deformation are measured along various directions relative to the loading direction. The acoustoelastic coefficients of PMMA are successfully determined from measurement results. The acoustoplastic effects of PMMA and silicon steel samples are also measured and determined. The investigation on the acoustoelastic and acoustoplastic effects demonstrates an effective way for estimating applied and/or residual stresses in solid materials nondestructively using the line-focused PVDF transducer and its measurement method.

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