• 作者： 李三保
• 作者服務機構： 國立清華大學材料科學工程學系
• 中文摘要： 　　我們探討了螺旋差排和裂縫之間的彈性交互作用。除了材料特性，幾何形狀與溫度在破裂上也扮演著重要角色。我們導出有表面裂縫之片狀材料的應力場，應力強度因子，裂縫延伸力和作用在差排上的鏡像力。由這些結果，我們發現小尺寸材料有較高韌性性。我們也利用不連續差排法提出破裂模式III的無差排帶模型。我們導出釋放差排的應力強度因子隨釋放差排數目的增加而增加。基於這些假設，我們得到無差排帶和塑性帶。因為釋放差排的應力強度因子是差排核半徑的函數，所以延性對脆性的轉變溫度也可加以合理解釋。
• 英文摘要： We investigate the elastic interaction between screw dislocations and cracks. In addition to materialproperties, geometry and temperature also play an important role in fracture. We derive the stress field,the stress intensity factor, the crack extension force and the image force on the dislocation in a finite sizeof material with a surface crack. From these results, we find that material of small size has high toughness.We also propose a dislocation-free zone model of mode III fracture using the discrete dislocation approach.We introduce the stress intensity factor for dislocation emission which increases with the emitted disloca-tion. Based on this assumption, we obtain the dislocation-free zone and the plastic zone. Since the stressintensity factor for dislocation emission is a function of the core radius of dislocation, ductile versus brittletransition temperature can also be explained.
• 中文關鍵字： screw dislocationl crack; stress intensity factorl dislocation emission
• 英文關鍵字： --