Atomistic investigation of the T-stress effect on fracture toughness of copper and aluminum single crystals

The T-stress effect on the fracture toughness of Cu and Al single crystals with the (010)[001] crack system was investigated based on atomistic simulations. The interatomic potential function of the embedded-atom method was used to model the face-centered cubic structures. A molecular statics approach using the conjugate gradient algorithm was employed to simulate mode-I fracture testing, and a K-field displacement with various magnitudes of T-stress was applied to load the simulation system. The critical energy release rates were calculated based on the global energy balance to evaluate fracture toughness, and the results were compared with asymptotic solutions obtained from conventional linear elastic fracture mechanics. The obtained values of fracture toughness exhibit a strong T-stress dependence for both the Cu and Al single crystals. Furthermore, the crack growth behavior is explained from an atomistic view of fracturing to analyze the T-stress effect on crack growth resistance.