Dynamic split tensile test of Brazilian disc of coal with split Hopkinson pressure bar loading

In order to study the tensile failure characterization of coal under impact loading, the split Hopkinson pressure bar was applied in the test of dynamic Brazilian disc split tension test of coals. The effects of impact velocity and bedding plane in the coals on the dynamic failure parameters, such as tensile strength, failure strain and strain rate, were discussed. A high speed camera and the Digital Speckle Correlation Method were used to analyze the dynamic failure process of coal samples. It is found that there are great effects of impacting speed and bedding plane of coal on the dynamic tensile failure features. With the increase of impacting speed, the dynamic tensile strength raises, but the rate of increase reduces. The failure strain reaches the maximum value as the impacting speed equal to 3.5 m/s. Moreover, at the almost same impacting speed and as the bedding plane of coal vertical to the loading direction, the failure strain is almost the maximum, but the strain rate reaches the minimum value. However, the dynamic tensile strengthfluctuates with the change of bedding plane. The split tensile failure dominate the failure process of coal as the bedding plane in coals vertical or parallel to the impact direction. In other directions of bedding plane, the tension-shear failure model was observed.