Simulation of ductile fracture of zirconium alloys based on triaxiality dependent cohesive zone model

The growth and coalescence of microvoids nucleating in the second phase particles are the dominant mechanism of ductile fracture. The ductile fracture process is strongly influenced by the stress state. Based on a triaxiality dependent cohesive zone model, the ductile fracture process of zirconium alloys under different stress states is described in the present study. Under the condition of plane strain, a compact tension analysis configuration is established for hydrided zirconium alloys composed of matrix and hydrides. By comparing our prediction with the results based on the extended finite element method, we can calibrate model parameters and then verify the model. The results show that the presence of hydrides accelerates the crack propagation and decreases the post-peak load level. Moreover, we find that the fracture resistance of zirconium alloys is strongly affected by the length, arrangement, quantity, and spacing of the hydrides. Specifically, for hydrides with the length along the crack propagation path, the increase in their length enhances the peak load and reduces the corresponding boundary displacement. The increase in their quantity reduces the post-peak load level. Besides, the increase in their spacing enhances the boundary displacement corresponding to the sudden load drop. For the ductile fracture of zirconium alloys, these simulation results provide insights into their ability to resist crack propagation.