Mechanical Characterization of 3D Printed Specimens

Abstract

Additive manufacturing (AM), also known as 3D printing, has been showing significant growth in recent years. Due to the several advantages, these processes provide, such as high process speed, the possibility for non-conventional geometries and a large range of materials; AM is quickly becoming an industry standard for both prototyping and end-user products. There are several 3D printing technologies available in the market, the most prevalent being fused deposition modeling (FDM), also known by fused filament fabrication (FFF). FDM is widely used as it is highly versatile and has the lowest entry level cost of any AM technology. Due to the layer-by-layer nature of the production procedure, 3D printed materials tend to behave with highly anisotropic properties. The main aspect that governs the anisotropy in FDM is the printing orientation. In order to study these effects, as well as select the optimal materials for future work, bulk specimens were produced from three different materials: polylactic acid (PLA), polycarbonate (PC), and thermoplastic polyurethane (TPU). These specimens were then submitted to tensile testing. In this work, the printing orientations used to manufacture the tested materials were 0°, 45°, and 90° for 100% line infill, with the bulk specimens being produced flat on the printing bed. Steps were taken to prevent layer adhesion failure as well as optimize the production of flexible materials, in this case TPU. The results were then compared with the specifications given by the supplier for FDM and with the raw material properties found in the literature. As expected, for all the specimens, infill orientation played a major role on both tensile strength and elongation. With the results presented in this work, it was possible to select TPU and PC as the most interesting materials to combine, given their broadly different properties. As for future work, a multi-material specimen will be produced, varying the percentage of each material as well as the placement and distribution on the testing bulk.