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第二章线弹性断裂力学线弹性断裂力学以理想的线性弹性裂纹体为对象,其结果可用于高强钢和厚截面中强钢(尤其工作温度较低时)的结构。线弹性断裂力学是断裂力学的理论基础和重要组成部分。一、能量平衡理论(一)格里菲斯(GRIFFITH)理论一九二○年格里菲斯通过对玻璃等完全脆性材料的断裂强度的实验研究认为:其实际断裂强度大大小于理论强度(实测值仅为理论值的1/10～1/1000),这是因为有一定大小裂纹存在,一次脆断是裂纹失稳扩展(快速扩展或加速扩展)的结果。并且从能量平衡的观点建立了脆性断裂判据,即裂纹体的裂纹失稳扩展的判据。
Chapter 2 Linear Elastic Fracture Mechanics The linear elastic fracture mechanics is based on the ideal linear elastic crack. The result can be applied to the structure of high-strength steel and heavy-gauge steel in thick sections (especially at lower operating temperatures). Linear elastic fracture mechanics is the theoretical basis and an important part of fracture mechanics. I. THEORY OF ENERGY BALANCE A. GRIFFITH Theory In 1920, Griffith, through an experimental study of the fracture strength of a completely brittle material such as glass, concluded that the actual fracture strength is much less than the theoretical strength The value is only 1/10 to 1/1000 of the theoretical value) due to the existence of cracks of a certain size. A brittle fracture is the result of crack instability expansion (rapid expansion or accelerated expansion). From the viewpoint of energy balance, the criterion of brittle fracture is established, that is, the criterion of crack instability propagation in cracked body.