Mixed modes crack paths in SCB specimens obtained via SLS

The paper presents experimental results of the crack path in Semi-Circular Bend (SCB) specimens obtained through additive manufacturing using Selective Laser Sintering (SLS) process. Determination of fracture parameters for components obtained via Additive manufacturing is a challenging topic, due to the influence of manufacturing parameters on the mechanical properties. Several researches provided the fracture toughness of SLS components, however there are not yet available results regarding the crack paths in such materials. The SCB specimens were designed with different crack orientations (0°, 15°, 30°, 45°, and 54°) and manufactured using EOS Formiga – SLS equipment (energy density 0.066 J/mm2, chamber temperature 169.5 °C, layer thickness 0.1 mm) using PA2200 material. The specimens were tested in symmetric three point bending configuration, creating 6 mode mixity from mode I (0° – crack orientation) to pure mode II (54° – crack orientation). Tests were performed at room temperature using 2 mm/min loading speed in a Zwick ProLine Z005 testing machine. For each crack orientation five specimens were tested. Crack initiation angle and crack propagation were measured by image digitization after the mechanical testing and presented in accordance to the initial orientation of the crack. Also, numerical simulation of crack path was conducted in the same way like the experiment and results were compared to the measured one.