This paper presents an experimental research on the length and shape of the fracture process zone of rocks under mode I, mixed mode (I + II) and mode II loading conditions for different geometries of cracked specimens made of two types of rocks, using the digital image correlation approach. Single edge notch bending (SENB) and semi-circular bend specimens are the two geometries considered. In order to investigate the effect of the specimen size on the fracture process zone length, rocks with three different sizes are produced and tested. To investigate the effect of the mode mixity on the fracture process zone length of marble and sandstone, the specimens are tested under different modes of loading. According to the experimental results, it is found that the fracture process zone length changes with mode ratio, specimen size, geometry and the material properties. The fracture process zone length increases when the mode of loading moves from mode I to mode II. Experimental results also show that fracture process zone becomes longer for specimens with larger sizes. The fracture process zone is also affected by the specimen geometry.

中文翻译：

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使用数字图像相关技术评估岩石中的断裂过程带：模式混合、尺寸、几何形状和材料的作用

本文针对两种岩石的不同几何形状开裂试样，在模式 I、混合模式 (I + II) 和模式 II 加载条件下，对岩石断裂过程带的长度和形状进行了实验研究。图像相关方法。单边缺口弯曲 (SENB) 和半圆形弯曲试样是考虑的两种几何形状。为了研究试样尺寸对断裂过程带长度的影响，制作并测试了三种不同尺寸的岩石。为了研究模式混合对大理岩和砂岩断裂过程带长度的影响，在不同的加载模式下对试样进行了测试。根据实验结果发现，断裂过程区长度随模态比、试样尺寸、几何形状和材料特性。当加载模式从模式 I 移动到模式 II 时，断裂过程区长度增加。实验结果还表明，对于较大尺寸的试样，断裂过程区变得更长。断裂过程区也受试样几何形状的影响。