A void nucleation and growth based damage framework to model failure initiation ahead of a sharp notch in irradiated bcc materials

• A continuum damage framework is developed to model failure initiation in irradiated bcc polycrystalline ensembles.
• Constitutive equations for vacancy condensation, void nucleation and growth are developed.
• The framework is used to model damage at dislocation channel interfaces ahead a sharp notch.
• The fracture toughness of irradiated specimens is calculated for various loading histories and notch geometries.
• Crack growth resistance of the irradiated specimens is computed and compared to that of the virgin specimens.

A continuum damage framework is developed and coupled with an existing crystal plasticity framework, to model failure initiation in irradiated bcc polycrystalline materials at intermediate temperatures. Constitutive equations for vacancy generation due to inelastic deformation, void nucleation due to vacancy condensation, and diffusion-assisted void growth are developed. The framework is used to simulate failure initiation at dislocation channel interfaces and grain boundaries ahead of a sharp notch. Evolution of the microstructure is considered in terms of the evolution of inelastic deformation, vacancy concentration, and void number density and radius. Evolution of the damage, i.e., volume fraction of the voids, is studied as a function of applied deformation. Effects of strain rate and temperature on failure initiation are also studied. The framework is used to compute the fracture toughness of irradiated specimens for various loading histories and notch geometries. Crack growth resistance of the irradiated specimens are computed and compared to that of virgin specimens. Results are compared to available experimental data.