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| Characteristics of tensile strength and fracture properties of coal#br#
based on semi-circular bending tests#br# |
| ZHAO Yixin1，2，GONG Shuang1，JIANG Yaodong2，3，HAN Chao3 |
| (1. School of Resource and Safety Engineering，China University of Mining and Technology，Beijing 100083，China；2. State Key Labratory of Coal Resources and Safe Mining，China University of Mining and Technology，Beijing 100083，China；3. School of Mechanics and Civil Engineering，China University of Mining and Technology，Beijing 100083，China) |
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Abstract Brazilian disc(BD) and semi-circular bending(SCB) tests were carried out to investigate the characteristics of tensile strength and fracture properties of coal under quasi-static loading. The SCB specimens with notches of various depths were tested to analyse the fracture properties of coal. The KIC fracture toughness and J-intergral fracture toughness of coal were calculated. The effects of notch depth on the fracture toughness were also discussed. The strain gauges were utilized to monitor the deformation features of specimens. The computed tomography scanning was also carried out on the failure specimens to figure out the crack distribution. Results show that SCB method is more suitable to obtain the tensile strength of coals than BD test. In the current testing situation，the coefficient of variation(CV) of KIC fracture toughness is the smallest as the dimensionless notch depth equal to 0.28. The KIC fracture toughness is easily affected by the notch depth and the dimensionless stress intensity factor(SIF). The results also indicate that the J-intergral fracture toughness is more suitable for evaluating the fracture properties of coals.
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2016, Vol. 35 
