Propagation and fracture mechanism of an internal crack in brittle solid based on 3D-ILC under uniaxial tension

Owing to the low tensile strength of rocks, internal crack expansion under tensile loading is highly susceptible to causing rock engineering failure without warning. In order to reveal the propagation and fracture mechanism of 3D internal cracks under tensile loading, uniaxial tensile tests. numerical simulations were carried out in this study using the 3D-ILC (3D-internal laser-engraved crack) method for prefabricated 3D internal cracks inside transparent rock-like materials. The results indicate that: under axial tension, the crack propagation surface is “S” shaped from the inside to the outside through the outer surface of the specimen, near the left and right side boundaries of the crack surface in the principal max tensile stress is approximately horizontal; According to the distribution and direction of the Wallner lines of the fracture surface, it is known that the prefabricated crack firstly propagates in the ring under the action of uniaxial tension and then changes into a wave shape to propagate to the transverse boundaries on both sides; The trend of crack propagation under uniaxial tension at different inclination angles was basically the same, and the relationship between K_II/K_I and crack deflection angle is revealed by mutual verification of the theoretical formula of energy release rate and numerical simulation results, i.e., the pre-crack inclination angle increases, K_II/K_I increases subsequently, and the crack deflection angle also increases. The research findings will serve as experimental and numerical references for studies on the propagation and fracture mechanism of internal cracks under tensile loading conditions across a spectrum of brittle materials, including rocks.