Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"quasi-brittle"”.
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A gradient-damage theory for quasi brittle fracture
Phase-field modeling of brittle fracture of linear elastic solids has been the subject of several studies in the past 25 years. An attractive feature of this approach to model fracture is its seamless ability to simulate the complicated fracture processes of nucleation, propagation, branching and …
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Three-dimensional peridynamic modelling of quasi-brittle structural elements
… of simulating the complex fracture processes in quasi-brittle materials. However, there is a lack of detailed validation studies in the literature, and significant work remains to quantify the predictive accuracy and generality of a peridynamic model. This thesis presents the development and …
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Higher-order discontinuous modelling of fracturing in quasi-brittle materials
Quasi-brittle failure is characterised by material degradation, fracturing and potential interaction of fragmented parts. The computational description of this behaviour has presented significant challenges to the mechanics community over the past few decades, driven by the development of …
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Fracture process zone : microstructure and nanomechanics in quasi-brittle materials
… tip. The context of this research is the FPZ in quasi-brittle materials, which is characterized by cracking at various scales. This study focuses on crack propagation and FPZ development at a fundamental material scale: the scale of the grain. With regard to the FPZ, the study seeks to understand …
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Failure processes in soft and quasi-brittle materials with nonhomogeneous microstructures
… a wide spectrum of failure behavior; in soft and quasi-brittle materials with nonhomogeneous microstructures considering a statistical distribution of material properties. The first topic we investigate considers the influence of interfacial interactions on the macroscopic constitutive response of …
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Three-dimensional modeling of failure in quasi-brittle materials and structures
… conditions, concrete structures present quasi-brittle behavior and failure due to the presence of a nonlinear fracture process zone ahead of the crack front. Predictive models and design methodologies have to be able to reliably calculate the load capacity, or structural strength, of …
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Using 3D Printing to Improve the Impact Resistance of Sandwich Panels
… ULTEM-1010 was designed. It was then tested in quasi-static compression, bending and indentation, low-velocity impact and high-velocity impact regimes and then compared against two typical reference designs. The 3D printed ULTEM-1010 panel design showed a significant improvement in core …
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Fracture characterization of clays and clay-like materials using flattened Brazilian Test
… many years to study the mechanical behavior of brittle and quasi-brittle materials like concrete, rock, wood, and ceramics. To date, the application of fracture mechanics to soils has been limited to dry and partially saturated soils where soil consistency changes due to suction and tends to be …
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Adaptive finite element simulation of fracture: from plastic deformation to crack propagation
… remeshing for two types of structural systems: quasi-brittle and ductile. For ductile systems, we are interested in modeling the large deformations that occur before rupture of the material. The deformations can be so large that element distortion can cause lack of numerical convergence. Thus, …
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Fracture Tests for Bituminous-Aggregate Mixtures: Laboratory and Field Investigations
… concrete at low temperatures can be described as quasi-brittle and the fracture properties are specimen size dependent within the size range tested for this study (25 mm up to 450 mm). The DC(T) test was applied to forensic studies of pavement structures and fracture energy estimated from the …
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Investigation of the Addition of Basalt Fibres into Cement
… its prime ingredient) is that unlike steel it is quasi-brittle material. It tends to want to crack when tensile stresses develop. Fibres have been added to concrete for many years to reduce the amount of and size of cracks cause by temperature changes or shrinkage. In more recent years, …
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Damage analysis and mechanical response of as-received and heat-treated Nicalon/CAS-II glass-ceramic matrix composites
… fibers. Different damage modes such as "brittle" matrix crack propagation and "quasi-brittle" matrix crack propagation were observed in heat-treated specimens. Results obtained from microanalysis using an analytical scanning transmission electron microscope equipped with an energy …
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Potential-Based Fracture Mechanics Using Cohesive Zone and Virtual Internal Bond Modeling
… model is verified and validated by investigating quasi-static fracture, dynamic fracture, branching and fragmentation. For quasi-static fracture problems, intrinsic cohesive surface element approaches are utilized to investigate microstructural particle/debonding process within a multiscale …
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Nanomechanical studies of metallic glasses at ambient and elevated temperatures
… features upon deformation, including quasi-brittle failure along shear bands, extremely limited tensile ductility, and propensity for fatigue under cyclic loading. Though researchers have studied metallic glasses for the last fifty years, several fundamental aspects of the mechanical …
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Fracture of Asphalt Concrete: A Cohesive Zone Modeling Approach Considering Viscoelastic Effects
Asphalt concrete is a quasi-brittle material that exhibits time and temperature dependent fracture behavior. Softening of the material can be associated to interlocking and sliding between aggregates, while the asphalt mastic displays cohesion and viscoelastic properties. To properly account for …
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Investigation of Toughening Mechanisms in the Fracture of Asphalt Concrete Using the Clustered Discrete Element Method
Asphalt concrete is a quasi-brittle composite material which is composed of solid inclusions and a viscous matrix. The fracture of heterogeneous solids is a difficult problem to handle numerically due to the creation and continuous motion of new surfaces. A clustered discrete element method (DEM) …
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Development of a numerical technique for modelling of multi-stage hydraulic fracturing in shale reservoirs
… with user-defined subroutines. Considering a quasi-brittle multi-layer shale, two key scenarios including sequentially and simultaneously multi-stage HF from an individual wellbore are investigated. Validation of the numerical technique has been performed by comparing the solution for an …
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Mechanical and microstructural characterization of nuclear grade PCEA graphite
… across all mechanical tests verified predictable quasi-brittle behavior and provided representative reliability parameters. Digital Image Correlation (DIC) revealed fundamentally different deformation mechanisms under tension and compression. Tensile loading produced linear elastic behavior …
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Lattice-based peridynamic modeling of linear elastic solids
… often used in civil engineering structures. This quasi-brittle material, when reinforced with steel, develops cohesive cracks under loading even though it has adequate strength to carry service loads. Concrete often cracks even before the application of load, due to temperature changes and …
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Behaviour of High- and Ultra-High Performance Fibre Reinforced Concrete Flexural Members
Concrete is a quasi-brittle material that increases in brittleness as the compressive strength increases and as such plain high-strength concrete always fails in an explosive manner. Incorporation of randomly distributed discrete non-metallic or metallic fibres into conventional concrete mixes has …
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