Experimental Investigation of Dynamic Fracture Patterns of 3D Printed Rock-like Material Under Impact with Digital Image Correlation

This paper presents the results of an experimental study on the dynamic fracture behaviour of 3D printed rock-like disc specimens with various pre-existing flaw configurations under high strain rate loading. The 3D printing technology is utilized to prepare disc specimens containing a single or a pair of unfilled or filled flaws. A split Hopkinson pressure bar is employed to generate high rate loading on the specimens, while the digital image correlation (DIC) technique is adopted to determine the type of new cracks, and their initiation, propagation paths and coalescence types. The results show that the dynamic strengths of the 3D printed specimens are higher than the quasi-static ones. When under high strain rate loading, not only can the specimens with filled flaws carry more load than the corresponding specimens with an unfilled flaw, but also their cracking pattern is different as compared to the unfilled flaw counterpart. It is interesting to note that the dynamic peak loads are not dependent on the flaw inclination angle, while the quasi-static peak loads show obvious flaw inclination angle dependence. Moreover, DIC results reveal that under some specific flaw configurations, the filling material undergoes shear strain concentration and a shear band develops inside the filled flaws. Overall this study confirms the strong effects of the flaw configurations and filling material on the deformation and crack patterns of the 3D printed rock-like materials under impact loading.