Tensile Test Analysis of 3D Printed Specimens with Varying Print Orientation and Infill Density

The research conducted aimed to investigate the effect of varying print orientation and infill density on the mechanical properties of different 3D printed polymer specimens by conducting tensile tests. The Stratasys Fortus 900mc Material Extrusion printer was used to produce multiple samples of different materials, namely, Acrylonitrile Styrene Acrylate (ASA), Nylon 12, Nylon 12 Carbon Fibre, ULTEM 1010, and ULTEM 9085 which were subjected to tensile tests according to the ASTM D638 standard. Samples were printed in flat, side, and upright orientations with both sparse (50%) and solid (100%) infill densities. The samples were then tensile tested to obtain the Young's Modulus, ultimate tensile strength (UTS), yield strength, and strain at break. The results produced revealed that the solid infill specimens almost always outperformed the sparse infill specimens. In terms of print orientation, side-orientated specimens achieved higher values for the material properties, followed by the flat specimens, with the upright specimens producing the performance with the lowest values. There were, however, notable exceptions to the results trends mentioned above. These findings were analysed using fracture mechanics and composite theory to explain the unexpected behaviour.