岩石动态断裂韧性测试的失稳判据研究

根据应力强度因子和断裂韧性的定义,研究并分析了应力强度因子的影响因素;表明试件的几何尺寸和物质材料的应力强度水平对应力强度因子起着决定性因素。辨明了起裂韧性、断裂韧性和止裂韧性的区别与联系;针对断裂K准则,提出了动态断裂韧性测试中的失稳判据,即dσ/dt=0,得到了试件所受的最大载荷对应于裂纹的失稳判据;并通过SHPB冲击装置,对这个失稳判据进行了验证。发现在8.0×10~4到35×10~4MPa·m~(1/2)s~(-1)的加载速率范围内,试验所用玄武岩的动态断裂韧性随着加载速率的增大而增大的规律。

REASEARCH ON ROCK UNSTABLE FAILURE CRITERION OF DYNAMIC FRACTURE TOUGHNESS

From the original source of SIF (Stress Intensity Factor) and fracture toughness, research the relation between them. Describe the influential factor of SIF in detail, and express the geometry of the specimen and the strength of the material are the two main factors of the SIF. Then introduce the fracture toughness and distinguish the fracture initial toughness, fracture toughness and fracture arrest toughness. According to the empirical K fracture criterion and different toughness above, propose the crack unstable failure criterion, i.e. , corresponding to the maximum load during the impact process. Under the SHPB setup, verify the criterion and discover that the dynamic fracture toughness increase with the loading rate, especially during the loading rate between 8.0e4 and 35e4 .