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Stress triaxiality is one of the most important factors that controls fracture ductility. The objective of this study was to investigate the influence of stress triaxiality on fracture ductility for specimens’ printed using stereolithography (SL). Dog bone shape specimens were printed using Formlabs® Form 2 Desktop SLA 3D printer. The specimens were built layer by layer with the help of this 3D printer. Each layer of liquid photopolymer is solidified through a computer-controlled ultraviolet (UV) light source with a laser spot size of 140 𝜇m. A photopolymer resin supplied by the manufacturer which comprised of a proprietary mix of Methacrylated oligomers, Methacrylated monomer, photo initiators and trace amount of pigments and additives was used for printing the specimens. The length of the specimens was 92.06 mm and the width of the specimens in the gage length portion was 6 mm. Uniaxial tensile tests were conducted on 3D printed specimens. Numerical simulations of the uniaxial tensile tests were performed using the commercial finite element code, ABAQUS. Material properties of 3D printed specimens were calibrated using Abaqus/Isight. The stress triaxiality distribution in the critical cross section at a displacement corresponding to fracture displacement was evaluated. The maximum and average stress triaxialities at the critical cross section was recorded. Triaxiality versus equivalent strain to fracture was plotted for the tested specimens. The results indicate a strong dependence of fracture ductility on stress triaxiality for the 3D printed specimens investigated in this study.

Publication Date



New York, NY


Mechanical Engineering


Presented at the 13th World Congress of Computational Mechanics, New York, NY, July 23, 2018.

Influence of stress triaxiality on fracture ductility for stereo lithography