Investigation of Stress Concentrations in Parts Manufactured with Fused Deposition Modeling

Conference Abstract: Fused Deposition Modeling (FDM) is an additive manufacturing process that creates a part by heating a material and extruding that material layer by layer. This manufacturing process has grown rapidly in its industry presence. FDM is a desirable method due to its ease of manufacturability and customization. The existing literature is limited in exploring how traditional solid mechanic theory applies to predict the failure location. Previous research has led to non-intuitive results, as solid mechanic theory predicts that the stress concentration factor will reduce the material's ultimate tensile strength (UTS) for the specimen's effective UTS. Since the prior tests produced these results, it indicates potential reinforcement from the additional layers of material around the stress concentration location. This research was conducted on a "dog bone" shape specimen consisting of opposite semicircular edge notches, with a radius chosen such that the theoretical stress concentration factor remains constant compared to the first hole-shaped geometry. To investigate the failure location of the specimens further, this study aims to introduce "v" shaped notches and elliptical holes in the specimen. The printed specimens will continue with the gyrometric infill patterns with densities varying from 20% to 60%, will remain the same as the previously tested ones for continuity. The theoretical stress concentration factor remains the same based on the specimen's design, however, due to the sharpness that the "v" shape creates, the stress field at that location will have a higher maximum stress as compared to the semicircles. It leads to a higher probability of crack initiation and propagation through the effective area. Ultimately, the results will lead to be influential in 3D-printed products failure theories to help engineers manufacture with FDM and understand the failure locations.