Following the so-called cracking elements method (CEM), we propose a novel Galerkin-based numerical approach for simulating quasi-brittle fracture, named global cracking elements method (GCEM). For this purpose the formulation of the original CEM is reorganized. The new approach is embedded in the standard framework of the Galerkin-based finite-element method (FEM), which uses disconnected element-wise crack openings for capturing crack initiation and propagation. The similarity between the proposed global cracking elements (GCEs) and the standard nine-node quadrilateral element (Q9) suggests a special procedure: the degrees of freedom of the center node of the Q9, originally defining the displacements, are "borrowed" to describe the crack openings of the GCE. The proposed approach does not need remeshing, enrichment, or a crack-tracking strategy, and it avoids a precise description of the crack tip. Several benchmark tests provide evidence that the new approach inherits from the CEM most of the advantages. The numerical stability and robustness of the GCEM are better than the ones of the CEM. However, presently only quadrilateral elements with nonlinear interpolations of the displacement field can be used.
K E Y W O R D Scracking elements method, finite-element method (FEM), quasi-brittle fracture, self-propagating crack, standard Galerkin form
INTRODUCTIONThis work extends the cracking elements method presented in References 1 and 2. Fracture of quasi-brittle materials is accompanied by a fast strain softening process, resulting in a localized failure zone of very small size. 3,4 In the last decades, different approaches were presented. They are made of a continuum, 5,6 discrete 7,8 or particle/meshless 9-11 -based framework, embedded either in classical fracture mechanics, or in continuum damage mechanics, 12 or in an equivalent-type theory such as peridynamics and lattice models. [13][14][15] This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.