Crack Growth Simulation in Quasi-brittle Materials Using a Localizing Gradient Damage Model

Failure in quasi-brittle materials comes under an intermediate category of fracture failure, which includes different stages, i.e., micro-cracks nucleation, growth, and coalescence into a macroscopic crack. The different stages of failure result in a tension-softening structural response, which can be accurately modeled using the conventional gradient damage models. However, due to a constant interacting domain throughout the load history, conventional gradient damage models suffer from various drawbacks which limits their application to simulate the final stages of quasi-brittle failure process. In this contribution, the present work illustrates a thermodynamically consistent localizing gradient damage model, which successfully overcomes the drawbacks of conventional gradient damage models. The localizing gradient damage model uses an interaction function definition in the constitutive framework to take into account the diminishing nonlocal interactions, thus attaining a macroscopic crack in the form of a localized damage profile during the last stages of failure. The numerical accuracy of the model is tested against both mode-I and mode-II types of failure problems and compared with the experimental results.