Accurate numerical prediction of ductile fracture and micromechanical damage evolution for Ti6Al4V alloy

A CPB06-based Stewart-Cazacu micromechanical damage model is implemented and validated for Ti6Al4V material. It provides accurate numerical predictions in terms of macromechanical material response and damage accumulation. The Stewart & Cazacu-Tvergaard & Needleman-Thomason (SC11-TNT) based damage model presented here is developed and implemented in the finite element software Lagamine following a semi-implicit cutting plane algorithm and a well-chosen flow rule approach. The damage of the material is characterized by the porosity ratio contained within the material. It is modelled by void nucleation, growth and coalescence mechanisms. The onset of the coalescence is established by a criterion based on Thomason's approach. The macroscopic results obtained by the implemented model demonstrate a strong ability to predict the experimental elastoplastic mechanical behaviour of the material across a full deformation range and different types of loadings. At the microscopic level, the predicted accumulated porosity ratio of the material matrix at fracture exhibits a good correlation with the experimental observations. The element deletion feature, activated when a certain damage threshold is reached, provides a physical description of the loss of load-carrying capacity of the material during fracture.