Comparison of flexural strength in rectangular shape 3D-printed PLA samples with different grooves

The production of parts using 3D printing, which is a type of additive manufacturing, is expanding at a faster rate. This technology can produce complex geometries by depositing melting polymer material layer by layer. Polylactic acid (PLA) is one of the most widely used materials in this technology due to its good properties such as biodegradability and bio-compatibility, and parts manufactured with PLA are being used in various engineering applications. The strength of these layer-by-layer parts depends on the printing parameters such as the infill density, the orientation of the printed fibers, the speed and temperature of the print, the distance between the fibers, etc. Also, the presence of grooves in engineering parts, especially printed polymer layer-by-layer parts, can significantly affect the mechanical behavior of these materials. In this research, the strength of short grooved beam parts with three different geometries (U, V, key hole) printed with PLA material under quasi-static bending loading is investigated experimentally and statistically. The amount of load and fracture energy of the samples are measured and also the sensitivity to the geometry of the groove in the tested parts is evaluated. Fisher's test is used for pairwise comparison of the grooves' strength. The results of this research show that the groove with an angled corner is the weakest, while the circular groove has a higher resistance, and this resistance increases when the radius of the circle is increased.