Crack paths in plain and notched specimens of additively manufactured PLA under static loading

The aim of this paper is to investigate the way the infill angle affects, under static loading, the orientation of the crack paths in plain and notched additively manufactured polylactide (PLA). Un-notched specimens and samples containing a variety of geometrical features (i.e., notches) of 3D-printed PLA were fabricated horizontally by making the infill angle vary in the range 0º-90º. The generated experimental results demonstrate that, independently of the infill orientation, static breakage is the result of two different mechanisms, i.e., shear-stress-governed de-bonding between adjacent filaments and normal-stress-governed breakage of the filaments themselves. The combined effect of these two failure mechanisms results in the fact that the orientation of the crack paths fully depends on the orientation of the 3D-printed filaments.