Comparing approaches for predicting critical loads in 3D printed graphene-reinforced PLA plates containing notches

Abstract

This work provides a comparison of different methodologies that may be used to estimate critical loads in notched components. The use of 3D-printed composites in structural applications, surpassing the current prototyping application, requires the definition of safe and robust methodologies for the determination of critical loads. Considering that notches (corners, holes, grooves, etc.) are unavoidable in structural components, these stress risers affect the corresponding load-carrying capacity. This study compares the results obtained by applying two different methodologies: the Theory of Critical Distances (TCD) and the Averaged Strain Energy Density (ASED) criterion. Additionally, in the case of TCD, the Line Method, combined with Failure Assessment Diagrams, are used. These methodologies are employed to assess the critical loads in graphene-reinforced polylactic acid (PLA-Gr) plates manufactured by Fused Filament Fabrication with a fixed raster orientation at 45/-45. Furthermore, the plates contain two different notch types (U-notches and V-notches), and comprise various thicknesses (from 5 mm up to 20 mm) and ratios of notch length to plate width (a/W= 0.25 and a/W = 0.50). The comparison between the obtained experimental critical loads and the corresponding estimations derived from the application of the TCD and the ASED reveals that both approaches generate reasonably accurate results, with most of the predictions being safe.