Fracture Properties of Additively Manufactured Acrylonitrile-Butadiene-Styrene Materials

Additively Manufactured (AM) parts exhibit orthotropic behavior when loaded as a result of the layer-by-layer assembly commonly utilized. While previous authors have studied the effect of layer orientation on the tensile, flexural, and impact response of AM parts, the effect of layer orientation on the fracture response is not well established. Here we explore the effect of layer orientation on the fracture properties of Acrylonitrile-Butadiene-Styrene (ABS) materials fabricated through the Fused Filament Fabrication (FFF) process. Critical fracture toughness values of Single Edge Notch Bend (SENB) specimens with a pre-crack oriented either parallel or perpendicular to the direction of layer-by-layer assembly were compared. Results show that the inter-laminar fracture toughness (fracture between layers) is approximately one order of magnitude lower than the cross-laminar toughness (fracture through layers) of similarly manufactured parts. Contrasting brittle and ductile fracture behavior is observed for inter-laminar and cross-laminar crack propagation, respectively, demonstrating that the elastic-plastic response of AM ABS parts is governed by the orientation of the layers with respect to the direction of crack propagation.