Probabilistic prediction of mechanical behavior of additively manufactured product considering geometrical imperfections associated with building direction

Among uncertainties that should be considered in the validation of numerical simulation, this study focused on the manufacturing process-induced geometrical imperfection. As one of the newly developed manufacturing process, the additive manufacturing by selective laser melting is studied. Dumbbell type tensile specimens with circular hole were additively manufactured using nylon with different building directions, and the distorted circular hole was modeled as an elliptic shape. Representative geometrical parameters were defined and statistically measured. It was found out that the width of the manufactured specimens and the length of the shortest ligament linearly depended on a sine function of the building direction. The database constructed from geometrical measurement could be interpolated with respect to the building direction. Using the interpolation of the database, probabilistic finite element models successfully predicted before manufacturing the upper and lower bounds of the mechanical behavior. The proposed method was verified by image-based analyses of real specimens, then it was applied to the same specimen but with unexperienced building direction as well as to an S-shaped component with seven circular holes.