超薄玻璃近年來大量用於可攜式電子產品中作為結構元件或是顯示面板，由於玻璃脆性材料的特性，在切割玻璃時容易在邊緣產生碎屑與裂紋而影響玻璃品質，因此目前主要切割玻璃的技術為透過短脈衝皮秒/飛秒雷射聚焦在超薄玻璃內部進行改質，弱化局部玻璃材料，並透過外加機械力或熱應力的方式進行裂片，以提升玻璃邊緣的切割品質，另外在外型的切割上，國內廠商對於開放式改質路徑已掌握切割技術，但是對於封閉式改質路徑切割的技術卻仍有很大的阻礙，因此本論文提出一套實驗逆向分析的方法量化殘留應力場及殘留應變場，同時預測超薄玻璃切割下料的發生。

短脈衝皮秒/飛秒雷射進行切割會在作用區周圍產生殘留壓應力場與殘留應變場，而主要用於量測雙折射材料殘留應力的光彈法解析度並無法達到所需的尺度要求，因此本文先使用光學顯微鏡觀察玻璃內部長光刀貝索光路皮秒雷射改質區的形貌為圓柱結構，接著透過實驗逆向分析將研究分為兩個部分，第一部分對超薄玻璃狗骨頭試件進行單軸拉伸實驗得到不同改質間隔的破斷應力，以及對未改質的素玻璃進行雙環彎矩實驗得到玻璃的破裂應力，再透過空孔陣列應力集中現象解析解及建立有限元素模型模擬單軸拉伸實驗，量化局部的殘留應變場大小；第二部分建立另一個有限元素模型模擬封閉圓形路徑裂片實驗，在圓形路徑中央施加冷卻源產生熱應力的方式，使得玻璃沿著圓形封閉路徑成功裂片下料，此有限元素模型除了可以預測玻璃破裂的發生，同時可驗證第一部分量化之殘留應力場與殘留應變場。

In this study, the residual stress field associated to the ultrashort-pulsed laser is investigated by using an experimentally conducted inverse approach. The effects of laser parameters on the local damage on glass were first examined. From the microscopic analysis, it was observed that the picosecond laser irradiation results in a cylindrical hole and a surrounding process zone of diameters around 1 µm and 3 µm, respectively. The relationship between glass fracture strength and laser irradiation pitch was obtained from a series of uniaxial tensile and ring-on-ring tests. The analytical solutions of stress field between two neighboring holes show that not only the stress concentration effect but also residual stress and strain field in the process zone contributes to reduce the tensile strengths. Numerical finite element simulations were then performed to consider the mechanical tests for evaluating the residual stress developed from the laser irradiation. From the correlation between the numerical and experimental results, it was determined that the cylindrical process zone created by the laser irradiation is under compressive state, which may be attributed to the rapid vaporization of the glass material at the focal line of the Bessel beam. The compressive process zone is accompanied by a tensile circumferential stress field in the neighboring region. Consequently, the fracture strength of the picosecond-laser processed glass is lower compared to the unprocessed glass. The numerical model was also implemented to study the process for creating a hole. Stress field around a circular path of laser irradiation was modeled, and the resulting maximum cleavage stress contour for a combined laser-induced residual stress and the subsequently applied thermomechanical stress is shown in Fig. 2. The cracking predictions based on the numerical model was confirmed by an experimental evaluation under the same process condition.

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