Experimental and numerical investigation on crack propagation for a zigzag central cracked Brazilian disk

This study examines the influence of zigzag joint configuration on crack propagation in centrally cracked Brazilian disks subjected to diametric forces, employing a 2-dimensional Particle Flow Code (PFC2D). An 80-mm-diameter disk specimen was used, featuring a single zigzag joint positioned at its center. The angles between the zigzag joint walls varied (45 degrees, 90 degrees, 135 degrees), and the angle between loading and joint direction ranged from 0 degrees to 90 degrees. Testing was conducted under Brazilian indirect tensile (Splitting tensile test) conditions, with Acoustic Emission (AE) data utilized to analyze fracture progression. The movements of the boundary rate were kept at 0.005 mm/s. Brazilian tensile strength and uniaxial compression strength of samples were 0.8MPa and 7.4 MPa, respectively. The failure strengths were found to be contingent on the specific failure mechanism, which, in turn, was influenced by the geometric attributes of the flaws considered. The maximum failure force correlated with the number of tensile cracks, which increased as the zigzag notch angle decreased. Initial loading exhibited few AE events, but subsequently, AE hits escalated prior to reaching peak force, with the number of hits increasing as the zigzag notch angle decreased. The failure pattern and maximum force observed in specimens closely mirrored results obtained through both numerical simulations and experimental methods.