Experimental Determination of Tensile Stress Concentration Factors of 3D-Printed PLA Polymers: Fillet Radius, Hole Diameter, and Infill Density

3D-printing technology is being used as a regular approach in prototyping and the production of machine components. However, despite their metallic counterparts, there are many issues including infill pattern, density, and stress concentration coefficient in 3D printing that are not well-defined. The infill density plays a significant role in the printing time and mechanical properties of the printed objects. On the other hand, like metallic materials, changing geometry, such as fillet radius and hole alters the strength of the printed elements. In this work, experimental works have been conducted to determine the effect of infill density on the tensile strength of 3D printed elements. Furthermore, various standard specimens for tensile testing have been prepared to investigate the effects of fillet radius and in-plane hole diameters on the tensile strength of PLA 3D-printed elements with different infill density. Using the experimental results, the tensile stress concentration coefficients as a function of fillet radius, hole diameters, and infill density have been determined. The results of the present work can be used as a guideline for analytical design and manufacturing 3D printing objects.