The Semi-Circular Bend (SCB) dynamic fracture toughness test, performed by the split-Hopkinson pressure bar, is simulated using a discrete element model. The influence of fracture constitutive law, loading rate and frictional boundary condition on the test measurements is investigated. It is found that friction between loading bars and rock specimen will severely affects on the test results and must be, therefore, considered carefully to secure the accuracy of the measurement. Simulation results also show that a rate-dependent fracture law is needed to predict the test data properly. Furthermore, the study suggests that the SCB specimen fractures before the peak dynamic load, based on which dynamic fracture toughness is calculated, is reached. Hence, the technique overestimates the dynamic fracture toughness of material.

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