Fatigue strength of plastics components made in additive manufacturing: first experimental results

Evolution of additive manufacturing (AM) techniques is making these innovative technologies more and more available and known to a larger audience. This allowed components built with AM techniques, especially metallic ones, to be effective in substituting similar components made with traditional technologies; with all the advantages of AM that make these components even more interesting in terms of performance. With plastics this process is relented also due to the chronic lack of established knowledge of the plastic materials, both in terms of strength, design criteria, both in long term behavior but also in static short-term properties. This work tries to give some useful information about the fatigue behavior of one class of material widely used with the mostly widespread AM technique for plastics, that is filament deposition modeling (FDM). The material considered is acrylonitrilebutadiene-styrene (ABS), used in countless components (electronic devices, household appliances, medical tools, and others) due to its excellent mechanical performances and relatively good workability. The property mainly analyzed in this work is fatigue behavior. Fatigue tests were performed in plane bending on specimen very similar to the type proposed and used by Nicoletto (2018) in different manufacturing and loading conditions. The obtained results offer an interesting insight into the properties of small components in ABS made by FDM and the effects of some influencing parameters: different stress-ratios were considered, as well as technological variations such as deposition direction. Experiments reveal that the scatter of fatigue data, even with the manufacturing uncertainties and defects typical of AM, can be controlled and within reasonable limits.