Effect of loading rate on fracture toughness and failure micromechanisms in marble

Fracture experiments in a notched semi-circular bend configuration were conducted to characterize rate effects and failure micromechanisms of a marble using a servo-hydraulic machine and a modified split Hopkinson pressure bar. Three real-time measurement techniques were used to estimate crack propagation velocities and full-field deformation fields. Micro-measurement techniques were employed to qualitatively and quantitatively identify micrograph and surface morphology. Based on the theory of fracture mechanics, a micromechanical model was presented to examine the intergranular and transgranular fracture. The results indicated that fracture toughness and surface roughness were dependent on loading rate, which were induced by the intrinsic failure mechanisms.