Numerical and experimental studies of additively manufactured polymers for enhanced fracture properties

A combination of computational and experimental investigation is performed to study additively manufactured (AM) polymers for enhanced fracture properties. Single edge notch tension specimens made of acrylonitrile-butadienestyrene (ABS) materials through fused deposition modeling with various build/raster orientations are studied, namely, horizontal builds with 45 degrees/-45 degrees (45-45) or 0 degrees/90 degrees (0-90) raster orientations, and vertical builds with layers perpendicular to the notch (V0). The measured fracture properties were found to highly depend on the build/raster orientations and crack kinking was observed in 45-45 samples to follow the weak inter-filament weld-lines. The extended finite element method (XFEM) using cohesive segment approach with anisotropic damage initiation and evolution criteria was developed to capture the dependency of fracture behaviors on build/raster orientations. Numerical parametric studies further show that the inter-filament bonding strength could be tuned to create alternate crack paths for maximum energy dissipated in AM polymer fracture. Finally, toughening mechanisms using topological patterns on the sample surface to deflect crack paths are demonstrated in experiments. This study sheds light on optimization of AM polymers for enhanced fracture properties.