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Title: Computational technology for damage and failure analysis of quasi-brittle materials
Author: Wang, Xiaofeng
ISNI:       0000 0004 5990 1073
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2015
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The thesis presents the development and validation of novel computational technology for modelling and analysis of damage and failure in quasi-brittle materials. The technology is demonstrated mostly on concrete, which is the most widely used quasi-brittle material exhibiting non-linear behaviour. Original algorithms and procedures for generating two-dimensional (2D) and three-dimensional (3D) heterogeneous material samples are developed, in which the mesoscale features of concrete, such as shape, size, volume fraction and spatial distribution of inclusions and pores/voids are randomised. Firstly, zero-thickness cohesive interface elements with softening traction-separation relations are pre-inserted within solid element meshes to simulate complex crack initiation and propagation. Monte Carlo simulations (MCS) of 2D and 3D uniaxial tension tests are carried out to investigate the effects of key mesoscale features on the fracture patterns and load-carrying capacities. Size effect in 2D concrete is then investigated by finite element analyses of meso-structural models of specimens with increasing sizes. Secondly, a 3D meso-structural damage-plasticity model for damage and failure analysis of concrete is developed and applied in tension and compression. A new scheme for identifying interfacial transition zones (ITZs) in concrete is presented, whereby ITZs are modelled by very thin layers of solid finite elements with damage-plasticity constitutive relations. Finally, a new coupled method named non-matching scaled boundary finite element-finite element coupled method is proposed to simulate crack propagation problems based on the linear elastic fracture mechanics. It combines the advantage of the scaled boundary finite element method in modelling crack propagation and also preserves the flexibility of the finite element method in re-meshing. The efficiency and effectiveness of the developed computational technology is demonstrated by simulations of crack initiation and propagation problems.
Supervisor: Jivkov, Andrey Sponsor: University of Manchester
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Quasi-brittle material ; Concrete ; Random generation and packing ; Crack propagation ; Size effect ; ITZ ; CZM ; Damage-plasticity ; SBFEM ; Monte Carlo simulation