Study of mixed-mode I/II fractures using single cleavage semicircle compression specimens under impacting loads

In order to study the fracture behavior of mixed-model I/II cracks under dynamic loads, a single cleavage semicircle compression (SCSC) specimen was proposed, and by using these specimens, rock dynamic fracture experiments for pure mode I and mixed-mode I/II under the impact of split Hopkinson pressure bar (SHPB) were conducted. Crack propagation speed was measured by using a crack propagation gauge (CPG) system and a high speed photography system, respectively. In order to confirm the experimental results, several numerical models for pure mode I and mixed mode I/II were established by using cumulative damage (CD) failure criterion, and by using these models, crack propagation behavior was simulated by using AUTODYN code. Generally, the results of crack propagation paths predicated by the numerical simulation agree well with the experimental results. This study shows that during crack propagation, the propagation speed is not a constant, and it may arrest for a moment. The new configuration specimen SCSC proposed in this paper is applicable in studying dynamic fractures by combining with SHPB device.