Influence of partial separation between rock specimen and loading device on determination of Mode II fracture toughness by shear-box test

IF 2.5 3区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

International Journal of Fracture Pub Date : 2025-07-29 DOI:10.1007/s10704-025-00876-w

Huai-Zhong Liu, Wan-Xi Liang, Hong-Qiang Xie, Li Zhuo, Ming-Li Xiao, Jiang-Da He

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Abstract

Shear-box loading could partially separate rock specimen and loading device to keep moment balance, but the influence of the partial separation has not been considered in determining Mode II fracture toughness. In this study, the finite element method was employed to analyze the separation states between rock specimen and loading device in the shear-box tests with various loading angles, and the influences of the separation state on the stress intensity factors and Mode II fracture toughness were investigated by recalibrating the Mode I and Mode II dimensionless shape factors. The results indicate that the separated length increases as the initial crack length or the loading angle increases. If the separation state is not considered in the mechanical analysis, the average relative errors of the resulted Mode I and Mode II stress intensity factors are about 21.66% and 11.06%, and the relative errors of the Mode II fracture toughness determined by the Mohr–Coulomb fracture criterion are greater than 9.3%. Therefore, the influence of the separation state between rock specimen and loading device cannot be ignored in the fracture analysis of the shear-box test.

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岩石试样与加载装置部分分离对剪切箱试验测定II型断裂韧性的影响

剪切箱加载可以使岩石试样与加载装置部分分离以保持力矩平衡，但在确定II型断裂韧性时未考虑部分分离的影响。本研究采用有限元方法分析了不同加载角度剪切箱试验中岩石试样与加载装置的分离状态，并通过重新标定I型和II型无量纲形状因子，研究了分离状态对应力强度因子和II型断裂韧性的影响。结果表明：随着初始裂纹长度和加载角度的增大，分离长度增大；在力学分析中不考虑分离状态的情况下，得到的ⅰ型和ⅱ型应力强度因子的平均相对误差分别为21.66%和11.06%，由Mohr-Coulomb断裂准则确定的ⅱ型断裂韧性的相对误差大于9.3%。因此，在剪切箱试验的断裂分析中，试件与加载装置分离状态的影响是不可忽视的。

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来源期刊

International Journal of Fracture 物理-材料科学：综合

CiteScore

4.80

自引率

8.00%

发文量

审稿时长

13.5 months

期刊介绍： The International Journal of Fracture is an outlet for original analytical, numerical and experimental contributions which provide improved understanding of the mechanisms of micro and macro fracture in all materials, and their engineering implications. The Journal is pleased to receive papers from engineers and scientists working in various aspects of fracture. Contributions emphasizing empirical correlations, unanalyzed experimental results or routine numerical computations, while representing important necessary aspects of certain fatigue, strength, and fracture analyses, will normally be discouraged; occasional review papers in these as well as other areas are welcomed. Innovative and in-depth engineering applications of fracture theory are also encouraged. In addition, the Journal welcomes, for rapid publication, Brief Notes in Fracture and Micromechanics which serve the Journal''s Objective. Brief Notes include: Brief presentation of a new idea, concept or method; new experimental observations or methods of significance; short notes of quality that do not amount to full length papers; discussion of previously published work in the Journal, and Brief Notes Errata.