IZOD impact properties of full-density fused deposition modeling polymer materials with respect to raster angle and print orientation

One of the fundamental characteristics of additively processed materials is that they are naturally anisotropic; this variance in mechanical properties is primarily generated through the formulation of patterned shell and in-filled regions within the material during processing. This paper describes the formulation and results of a study to ascertain the impact strength of various full–infill polymer-based materials processed in various orientations and angles via fused deposition modeling. Ten different materials were tested using seven different hatch angles and three print orientations. Seven different pure materials were tested, as well as three composites; these were acrylonitrile butadiene styrene, standard polylactic acid, high-temperature polylactic acid, high-impact polystyrene, nylon, polyethylene terephthalate + glycol, polycarbonate, aluminum polylactic acid, wood polylactic acid, and carbon–fiber polylactic acid. All experiments were carried out using ASTM IZOD Type E tests with a 2.7J pendulum. Five replications of each test combination were collected, for a total of 1050 tests. The results showed that the shell orientation and raster angle were primary drivers in determining impact properties, as they strongly influenced the crack length and path though the material during fracture. This was especially clear for the polycarbonate, nylon, and polyethylene terephthalate + glycol which underwent large plastic deformation during the tests. It was further observed that the impact toughness was inversely correlated with test repeatability, with the toughest materials having the highest variability between test replications.