Simulation of quasi-brittle fracture of lamellar GammaTiAl using the cohesive model and a stochastic approach

Abstract

Quasi-brittle fracture of fully lamellar two-phase (α2 + γ)TiAl is simulated and analysed using the cohesive model. Applications of the model for predicting crack initiation, propagation and unstable fracture are discussed and validated by fracture tests. The experiments have been conducted at room temperature, where specimens exhibit small force drops (pop-in) during stable crack propagation and all end by unstable failure. The global behaviour of the specimens is simulated by adjusting the cohesive parameters and the shape of the cohesive law using stochastic considerations. A systematic analysis is carried out and various aspects of modelling and simulation are discussed including the contribution of the specific lamellar microstructure. To some extent, the cohesive model can explain and describe the physical phenomena of the two-phase material.