Simulation of finite-width process zone in concrete-like materials by means of a regularized extended finite element model

Experimental tests carried out on concrete specimens show that a fracture process zone with finite width develops in front of the crack tip. Currently, the only way of modelling a finite-width process zone is to adopt a non-local continuum damage model. This choice, however, precludes the description of macro-cracks, which emerge during the late stage of the cracking process. The eXtended Finite Element Method is a powerful tool for modelling the cracking process. The proposed eXtended Finite Element approach can simulate in a unified and smooth way both the formation of a process zone with finite width and its subsequent collapse into a macro-crack. Weak points of existing formulations, such as the necessity of ad hoc strategies in order to get mesh-independent results, and the sudden loss of stiffness at the transition from the continuous to the discontinuous regime, are overcome. In the case of tensile cracking, effectiveness is tested through comparisons with numerical and experimental results.