Dynamic mixed mode I–II fracture of notched Brazilian discs fabricated by additive manufacturing

Considering applications of Additive Manufacturing (AM, i.e., 3D printing) in manufacturing of end-use products, the ability of 3D-printed components to withstand mechanical stress has grown in importance. In this respect, Notched Brazilian Disc (NBD) specimens are designed and fabricated based on the vat photopolymerization technique. In a series of experiments, we examined the NBD specimens under static and dynamic loading regimes. Particularly, we used the conventional Split Hopkinson Pressure Bar (SHPB) includes aluminium incident and transmission bars which generates a strain rate of 25 s⁻¹. Notably, mixed mode I–II fracture is studied by diametrically loaded specimens with varying notch inclination angle values (0° to 90° with a 15° increment). In the experimental tests, a high speed camera is utilized as non-contact optical method to document the process from initial impact till the specimen failure. Parallel to the experiments, finite element models are developed to determine the dynamic mechanical response of the notched discs. The experimental findings and numerical outcomes have been compared, and the convergence investigated. In addition, a 3D laser microscope and a free-angle observation system have been used to study failure patterns and crack propagation paths in the specimens with initial notch. The documented findings can be used for new designs of 3D-printed parts with customized mechanical behavior and enhanced structural performance.