Effect of Processing Parameters on Interlayer Fracture Toughness of Fused Filament Fabrication Thermoplastic Materials

Abstract

Additive manufacturing by fused filament fabrication (FFF) is a promising method for rapid manufacturing of complex components for a wide variety of applications. FFF is often limited to non-structural and non-load bearing applications due to insufficient strength and stiffness of the end-material. This is particularly true in the direction of layer deposition, due to poor adhesion between FFF layers. Processing parameters such as extrusion temperature and print speed have been shown to have significant effect on the mechanical performance of FFF components, but these studies have often neglected interlayer properties. This work develops and experimental approach for quantifying the relationship between processing parameters and interlayer fracture toughness of FFF specimens. The processing parameters considered include extrusion and bed temperatures, extrusion speed, raster spacing, and cooling-fan speed. FFF test blocks were fabricated to identify which parameters would best optimize interlayer fracture toughness. To measure interlayer fracture toughness, unidirectional ABS double cantilever beam specimens were fabricated according to the parametric test matrix with guidance from the test block results. In situ full-field thermography was used to record the specimen thermal history during fabrication. X-ray computed tomography was used to determine the internal void resulting from varying the raster spacing. Finally, optical and SEM fractography was used to perform post mortem categorization of specimen fracture surfaces. The fracture toughness data measured in this study is used to develop an approach for rapid optimization of interlayer properties of FFF components.