Apparent fracture toughness estimation of additively manufactured alumina from as‐printed chevron‐notched test specimens

Abstract Ceramic vat photopolymerization (VPP) is a digital light processing method used to make additively manufactured green ceramic components that are then sintered. Despite the ever‐advancing maturation of this method's green‐state process, some of the material properties of sintered VPP‐processed ceramics are still not well defined or understood. One example is Mode I fracture toughness, K Ic . In this study, attention was devoted to K Ic measurement using net‐shape chevron‐notched bend bars that were VPP‐processed and the examination of whether valid K Ic measurement could occur by testing them. Stable crack propagation was observed in >60% of tested samples, indicated by a smooth nonlinear transition through the measured maximum force prior to final fracture. However, their results cannot yet be responsibly referred to as K Ic because of continuing violations of other prerequisites needed for valid K Ic testing.