Loading rate effects on cracking behavior of flaw-contained specimens under uniaxial compression

To investigate the loading rate effects on the cracking processes of flaw-contained specimens under compressive loading, rectangular parallelepiped specimens containing centrally located single and double flaw(s) are numerically loaded using the bonded-particle model (BPM). The study reveals that the uniaxial compressive stress ( and coalescence stress ( increase significantly, while the first crack initiation stress ( only subtly increases with the increase of loading rate. The trajectories of the first and secondary cracks become shorter while the amount of discrete micro-cracks increases as the loading rate increases. The mode of coalescence cracks changes from tensile-segments-dominant to shear-band-dominant when the loading rate increases. The shape of the stress-strain curves of specimens loaded at different rates also varies. Based on the present study, an upper limit of loading rate of 0.08 m/s deems to be acceptable for cracking processes analysis under static load using the BPM.