A remaining multiaxial ductility-based fracture toughness prediction model for metallic alloys

Predicting fracture toughness is an important part of developing an overall structural integrity methodology for components. This study therefore tries to establish a fracture toughness prediction model based on the concept of remaining multiaxial ductility exhaustion. Numerical simulation model which takes into account the level of constraint at the crack tip and the material's inherent multiaxial ductility is established to research fracture initiation and propagation. The core of the model is based on increasing load to consume the remaining multiaxial ductility of metallic alloys until final fracture. The presence of grains (G) and grain boundaries (GB) in the simulation model is used to highlight a sensitivity analysis on the local interaction of microstructural at mesoscale with regards to crack initiation and growth. The model has been validated with fracture toughness tests by using additively manufactured Ti6Al4V alloy compact tension (CT) specimens. It is shown that the predicted plane strain KIC compares well with results from both wrought and heat-treated additively manufactured test specimens. Future tests on different other materials using low/high constraint cracked geometries should strengthen the model's predictive capabilities for different fracture scenarios.