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.

► Quasi-static and dynamic fracture toughnesses were determined by NSCB specimens.
► The high-speed DIC technique was used for estimating full-field deformation fields.
► Micro-measurement techniques were employed to identify micrograph and morphology.
► Fracture toughness and the fractal dimension were dependent on loading rate.
► We proposed a micromechanical model to investigate IG and TG fracture behavior.