本論文目的乃以有限元素法模擬雷射熱破裂技術於切割脆性材料之熱應力分佈與變化，並以破壞力學的觀點，分析材料因雷射熱應力導致裂緣應力強度因子值局部上升，並探討材料中裂縫得以擴展之機制與參數影響。文中主要以玻璃基板切割為對象，分析雷射熱源、板材性質與冷卻源中的八項製程參數，對切割潛力、裂縫擴展時間以及裂縫落後熱源中心距離之影響。
雷射熱破裂技術在脆性材料加工中，由於其高加工品質及低設備需求之優點，近年已逐漸取代傳機械切割與雷射燒蝕技術。在模擬雷射切割的過程中，文中分別採用五個不同裂縫長度之有限元素模型，模擬裂縫擴展至不同長度加工過程時，其材料溫度場分佈與應力場狀態；並藉由虛擬裂紋閉合法和裂緣位移外插法，計算此刻裂縫前緣之應變能釋放率和應力強度因子，檢視該裂縫擴展情形或確保該裂縫能夠繼續延伸。分析結果顯示，縮減材料厚度、使用液體輔助冷卻與增加雷射熱源對材料表面之熱通量，均能提高成功切割材料之機會。且減少冷熱源間的相對距離，可有效縮短裂縫落後熱源之情形。數值結果，有限元素法確可有效應用於雷射熱破裂技術之分析與製程建立。

The finite element method has employed to simulate the laser thermal cracking process for brittle materials. The varieties of temperature and thermal stress distributions around the crack tip were studied. The effect of cracking parameters, i.e. laser power, focus moving speed, plate thickness, crack length, cooling effect… etc., on the crack propagation has also investigated.
The stress intensity factor around crack tip is considered as the key parameter to dominate the crack propagation. The thermal-plastic-elastic finite element model was employed to simulate the temperature and stress distributions. The strain energy release rate and stress intensity factor solved from virtual crack closure technique and displacement extrapolation method are employed to illustrate the crack state in this study. Five crack length models were used to show the stress intensity factor variations around the crack tip. Numerical results indicate that the head flux on the surface, substrate thickness and adopting cooling sources may affect the crack propagation, crack delay significantly. The results in this study also demonstrate the feasibility of employing finite element method in the exploring crack propagation mechanism in laser thermal cracking process.

目錄 i
表目錄 iv
圖目錄 v
符號說明 x
摘要 xiv
Abstract xv
第一章 緒論 1
1.1 前言 1
1.2 發展背景與文獻回顧 4
1.3 研究動機 9
1.4 組織章節 11
第二章 相關理論與方法 13
2.1 陶瓷材料基本特性與熱破裂切割機制 13
2.2 基礎破壞力學 16
2.3 有限元素處理裂縫問題 24
2.3.1 前言 24
2.3.2 裂緣位移外插法 28
2.3.3 虛擬裂紋閉合法 30
2.4 熱傳模式 36
2.5 力學模式 37
第三章 有限元素模型與分析方法 39
3.1 概述 39
3.2 研究步驟 40
3.3 建模方法與假設 42
3.3.1 材料性質與模型幾何 42
3.3.2 網格切割與接觸設定 44
3.3.3 初始條件與邊界條件 52
3.4 分析模式與模型驗證 57
3.4.1 離散化裂縫擴展問題 57
3.4.2 模擬過程之運算設定 60
3.4.3 有限元素模型之可靠度測試 64
3.5 參數規劃 71
第四章 數值結果與討論 75
4.1 初始製程參數下之模擬結果與熱破壞機制 75
4.2 雷射熱源之參數分析 99
4.3 板材之參數分析 107
4.4 冷卻源之參數分析 113
4.5 多熱源配置 122
第五章 結論 127
5.1 本文成果 127
5.2 未來展望 128
參考文獻 129

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