Finite element modelling of internal and multiple localized cracks

Abstract

Tracking algorithms constitute an efficient numerical technique for modelling fracture in quasibrittle materials. They succeed in representing localized cracks in the numerical model without mesh-induced directional bias. Currently available tracking algorithms have an important limitation: cracking originates either from the boundary of the discretized domain or from predefined "crack-root" elements and then propagates along one orientation. This paper aims to circumvent this drawback by proposing a novel tracking algorithm that can simulate cracking starting at any point of the mesh and propagating along one or two orientations. This enhancement allows the simulation of structural case-studies experiencing multiple cracking. The proposed approach is validated through the simulation of a benchmark example and an experimentally tested structural frame under in-plane loading. Meshbias independency of the numerical solution, computational cost and predicted collapse mechanisms with and without the tracking algorithm are discussed.

An improved crack tracking algorithm with self‐correction ability of the crack path and its application in a continuum damage model

“…A check was made on whether the crack root element was inside or on the boundary and a different propagation procedure was suggested for the two types of crack roots in the work of Saloustros et al In the present TA, it is not detected whether the crack root element is inside or on the boundary. That is, if an element satisfying a crack root generation condition is first found, it is selected as a crack root without checking whether it is an inner element or a boundary element.…”

“…These models also have no guarantee for the continuity of the crack path. To correctly predict the crack path by CDM and improve its performance, some studies about the CDM approach, in addition to the crack TA, have been performed recently . In fact, many issues occur for predicting the crack path if the TA is not used in the EFEM or XFEM.…”

“…To correctly predict the crack path by CDM and improve its performance, some studies about the CDM approach, in addition to the crack TA, have been performed recently. 19,22,23 In fact, many issues occur for predicting the crack path if the TA is not used in the EFEM or XFEM. Rabczuk 17 pointed out some shortcomings of the EFEM without a TA, given by the fact that the crack path is not continuous and that, for some discretizations, spurious crack paths may be obtained in fracture simulation.…”

A softening-healing law for self-healing quasi-brittle materials: Analyzing with strong discontinuity embedded approach

“…During damage of quasi-brittle materials, micro-defects merge into macro-cracks and the size of fracture zone reduces from finite width to almost zero in a very limited loading period, the behavior of which is localized and anisotropic, highly depending on the crack locations and orientations [33,34]. From this point of view, discontinuous models such as conventional interface element [35][36][37][38][39], Strong Discontinuity embedded Approach (SDA or E-FEM) and localization [40][41][42][43][44][45][46][47][48][49], nodal enrichment method eXtended Finite Element Method (X-FEM) [50][51][52][53][54][55][56][57] and phantom node method [58][59][60] could be more suitable for especially simulating the damage process of quasi-brittle materials, which holds much less mesh dependence than continuous method. Correspondingly, when using discontinuous models for self-healing quasi-brittle materials, as a pseudo reverse damage process, healing should also be considered in a discontinuous form e.g.…”

Tracking multi-directional intersecting cracks in numerical modelling of masonry shear walls under cyclic loading

“…Cyclic loading of masonry structures may result in complex damage patterns characterized by multiple and intersecting cracks. To appropriately model this, a novel numerical methodology is proposed, on the basis of the tracking algorithm developed in previous works [22,31,32], that allows the simulation of intersecting and multi-directional cracking, extending the use of tracking algorithms to a large field of applications. At the constitutive level, the paper presents a novel formulation in the context of a continuum damage model for the description of irreversible deformations under shear loading.…”