Influence of raster orientation on the determination of fracture properties of polypropylene thin components produced by additive manufacturing

Abstract

Additive manufacturing techniques are increasingly being used to produce components in different sectors, including industrial, aeronautical, education and medical applications. In order to predict the mechanical behaviour of these components, it is necessary to characterise materials according to their manufacturing process. Considering the technology of additive manufacturing by “fused filament fabrication” (FFF) or “fused deposition modelling” (FDM), and specifically in “material extrusion additive manufacturing” (ME-AM), several parameters must be defined to produce the required geometries. The infill orientation is one of the parameters that most affects mechanical and fracture properties of the final components, often causing premature failures. Therefore, the objective of this work is to study the influence of raster orientation on fracture parameters for thin polymer components. For this purpose, double deeply edge-notched tensile (DDEN-T) thin specimens have been tested considering the essential work of fracture (EWF) approach. The studied material has been polypropylene (PP). Experimental results show the influence of filament orientation on the essential work of fracture and the limitations of the EWF approach for some of the assessed orientations. Additionally, two different fracture mechanisms have been observed and discussed. This work demonstrates the importance of optimising the raster orientation during the filament deposition layer by layer, depending on the application of the manufactured component, to preserve its structural integrity.