Fracture behavior of additively manufactured acrylonitrile butadiene styrene (ABS) materials

The effect of layer orientation on the fracture properties of poly(acrylonitrile-butadienestyrene) (ABS) materials fabricated through the fused filament fabrication (FFF) process was explored. Critical elastic-plastic strain energy release rates of single edge notch bend (SENB) specimens with variable crack-tip/laminae orientations 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 direction of crack propagation within the laminated structure. Fracture surfaces of failed specimens are examined using scanning electron microscopy to show micro- and macro-scale toughening/embrittling mechanisms. Techniques for designing tougher additively manufactured materials based on biological analogies are discussed.