Multiscale fracture modelling of concrete using a variational micromechanics-enriched embedded strong discontinuity Finite Element Method

Azua-Gonzalez, Carlos 2022. Multiscale fracture modelling of concrete using a variational micromechanics-enriched embedded strong discontinuity Finite Element Method. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The focus of this research is the development of a novel physics-based variational multiscale formulation and its computer implementation for modelling diffuse directional microcrack growth and localised macrocrack propagation in a general class of quasi-brittle solids, the so-called cementitious composites. For this task, Micromechanics-based formulations at the material scale, previously developed at Cardiff University, have been improved to cope with deformation localisation objectively, by using Finite Elements with embedded strong discontinuities at the macroscale. The newly coupled numerical scheme seeks to enable a robust and efficient multiscale fracture propagation framework, which avoids remeshing. The framework predicts deformation and stress response at the homogenized bulk and predicts the propagation of macrocracks until failure is attained. In this context, failure is modelled as a consequence of progressive macroscopic softening with feedback from microscale material deterioration. This Micromechanics-enhanced nonlinear Finite Element framework with embedded strong discontinuities has been implemented into the in-house Fortran code Cardinal. In combination with an existing Matlab post-processor, interfaces have been coded between Cardinal and the open-source visualisation toolkit Paraview. In this way, meshes for representative problems were generated and display effectively. Finally, validation of the computational framework has been carried out by comparisons of numerical predictions against experimental data of benchmark-type Boundary Value Problems (BVPs) in unreinforced concrete specimens, under various mechanical actions including combined shear and normal deformation upon macrocrack nucleation.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Finite Elements , Multiscale analysis , Micromechanics , Fracture , Concrete failure
Date of First Compliant Deposit:	22 November 2022
Last Modified:	22 Nov 2022 11:20
URI:	https://orca.cardiff.ac.uk/id/eprint/154388

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