Effect of the notch opening angle on the quasi-static behavior of PLA and carbon fibers reinforced PLA realized through Fused Deposition Modelling

Abstract

Additive manufacturing provides significant advantages over conventional manufacturing. Among the others, the almost unconstrained freedom in the geometrical design for this technology can be pointed out. However, the geometrical complexness of such components requires for adequate tools to assess both their fracture behavior and fatigue life. A suitable solution for such a design challenge is to rely on the so-called local approaches whose main advantage is to consider a local parameter to evaluate the behavior of the entire component; besides, such methods have the advantage that their critical value can be assumed to be independent on both the overall geometry of the component and the loading conditions. With this purpose, the present work investigates the fracture behavior of notched specimens made of PLA and carbon fiber reinforced PLA realized through additive manufactured technique. The specimen's geometry considered is smooth and double notched while the notch opening angles varies between 30 and 120 degrees. The results of the experimental campaign have been summarized through the averaged strain energy density (SED) method, an energy-based local approach, widely proved to be a valid tool to investigate both fracture in static condition and fatigue failure. The critical value of SED has been obtained through the stress-strain curve of smooth specimens for the two studied materials. After the determination of the control volume characteristic length, R0, the data have been summarized in terms of averaged SED values. The critical loads for the different geometries and the different materials considered are predicted by the method with an average error of ±7%.