Static and fatigue behavior of 3D printed smooth and notched PLA and short carbon fibers reinforced PLA

Additive manufacturing (AM) offers various advantages, such as geometrical design freedom and highly tailored components. Among the AM technologies, fused deposition modeling (FDM) is one of the most commonly used methods for polymers. In this work, we analyze the fracture behavior of both smooth and notched specimens made from two different materials: polylactic acid (PLA) and short carbon fiber (CF) reinforced PLA. The experimental research revealed poorer static and fatigue properties for the PLA-CF specimens, regardless of the geometry. These poorer mechanical properties could be attributed to several factors, including higher porosity and poorer adhesion between filament layers. To assess the static and fatigue behavior influenced by the component geometry, the averaged strain energy density (SED) method was considered. After determining the characteristic length, R0, for both static and fatigue conditions, the data has been summarized in terms of averaged SED values. This method predicts the critical loads for different geometries and materials considered with an average error of ± 7 %. Additionally, a SED-based fatigue curve, independent of the geometry, has been determined for both materials.