Experimental and Theoretical Fracture Assessments of Blunt V-Notched Rock Samples Under SHPB Impact Loading

This paper investigates the dynamic fracture resistance of blunt V-notched rock samples using the experimental and theoretical methods. The semi-circular bend sample, made of Fangshan granite, weakened by an edge blunt V-notch is selected as the testing rock sample. An empirical formula for calculating the dynamic notch fracture toughness of blunt V-notched samples is established by the stress extrapolation method in the finite-element method (FEM). According to the established empirical formula, the dynamic notch fracture toughness of the testing rock samples under split Hopkinson pressure bar (SHPB) impact loading condition are obtained from the dynamic strain signals in pressure bars. The experimental results reveal that the dynamic notch fracture resistance depends heavily on the opening angle, notch radius, and loading rate. A modified mean stress (MS) criterion is proposed to assess the dynamic fracture onset of blunt V-notched rock samples, which agree well with that obtained from the experimental data. These conclusions show that the proposed experimental and theoretical methods are capable of accurately assessing the dynamic strength of blunt V-notched specimen being tested, which may have significant implications to assess the dynamic fracture in notched rock samples and other brittle components.