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Design of bi-adhesive joint for optimal strengthVennapusa, Siva Koti Reddy January 2019 (has links)
To support the trust in the design development of adhesively bonded joints, it is important to precisely predict their mechanical failure load. A numerical simulation model with a two-dimensional linear elastic cohesive zone model using a combination of a soft and a stiff adhesive is developed to optimize the strength of a lap-joint. Separation under mixed-mode conditions (normal and shear direction) is considered. By varying the length of the adhesives, the fracture load is optimized. The results obtained from the numerical experiments show an improvement in strength.
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Solving three-dimensional problems in natural and hydraulic fracture development : insight from displacement discontinuity modelingSheibani, Farrokh 26 September 2013 (has links)
Although many fracture models are based on two-dimensional plane strain approximations, accurately predicting fracture propagation geometry requires accounting for the three-dimensional aspects of fractures. In this study, we implemented 3-D displacement discontinuity (DD) boundary element modeling to investigate the following intrinsically 3-D natural or hydraulic fracture propagation problems: the effect of fracture height on lateral propagation of vertical natural fractures, joint development in the vicinity of normal faults, and hydraulic fracture height growth and non-planar propagation paths. Fracture propagation is controlled by stress intensity factor (SIF) and its determination plays a central role in LEFM. The DD modeling is used to evaluate SIF in Mode I, II and III at the tip of an arbitrarily-shaped embedded crack by using crack-tip element displacement discontinuity. We examine the accuracy of SIF calculation is for rectangular, penny-shaped, and elliptical planar cracks. Using the aforementioned model for lateral propagation of overlapping fractures shows that the curving path of overlapping fractures is strongly influenced by the spacing-to-height ratio of fractures, as well as the differential stress magnitude. We show that the angle of intersection between two non-coincident but parallel en-echelon fractures depends strongly on the fracture height-to-spacing ratio, with intersection angles being asymptotic for "tall" fractures (large height-to-spacing ratios) and nearly orthogonal for "short" fractures. Stress perturbation around normal faults is three-dimensionally heterogeneous. That perturbation can result in joint development at the vicinity of normal faults. We examine the geometrical relationship between genetically related normal faults and joints in various geologic environments by considering a published case study of fault-related joints in the Arches National Park region, Utah. The results show that joint orientation is dependent on vertical position with respect to the normal fault, the spacing-to-height ratio of sub-parallel normal faults, and Poisson's ratio of the media. Our calculations represent a more physically reasonable match to measured field data than previously published, and we also identify a new mechanism to explain the driving stress for opening mode fracture propagation upon burial of quasi-elastic rocks. Hydraulic fractures may not necessarily start perpendicular to the minimum horizontal remote stress. We use the developed fracture propagation model to explain abnormality in the geometry of fracturing from misaligned horizontal wellbores. Results show that the misalignment causes non-planar lateral propagation and restriction in fracture height and fracture width in wellbore part. / text
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Investigation of the reliability deterioration of ageing marine structuresLouvros, Dimitrios 09 1900 (has links)
In the present work, an investigation of the fatigue life benefits emerging from
fillet weld geometries optimization has been carried out.
At first, an introduction to ageing mechanisms, corrosion and especially fatigue,
acting on operating marine structures has been made. Residual stresses at
weld toes, stress modes, and types, geometrical factors (weld angle, toe radius,
leg length), welding techniques selected, post-welding treatment and plate‟s
material are some of the principal factors affecting the fatigue life of a fillet weld
joint.
Especially, the accuracy of various approaches in fatigue life estimation of
specific geometries under pre-set types and levels of stress is studied. It is
evident so far that even the notch stress concept is the most accurate method
based on S-N curves, the Fracture Mechanics approach can offer more
accurate solutions of a crack development through the material. Towards this, a
literature review on crack evolution aspects in welded and non-welded plates
under bending and tension was performed; substantial parameters were
determined and finally implemented in the LEFM model which was used for the
simulation purposes of Chapter 6.
As far as the crack aspect ratio evolution is concerned, an extensive reference
is available in literature since many researchers have investigated its
contribution to the determination of geometrical paths, commonly known as
“Preferred Propagation Paths”. Their significance is related with our ability to
determine accurate SIF solutions leading to precise fatigue life estimations.
A typical fillet weld joint 2-D model has been developed in CAE Abaqus
software and a Finite Element Analysis of subject T-profile has been carried out.
Through this analysis, the fillet weld angle, the weld leg length, the weld toe
curvature radio ρ and the carrying load plate thickness are examined for their
impacts on the maximum surface stress. Finally, a number of stress mitigating
measures are proposed and their effects are analyzed.
Undoubtedly, the notch stress concept today is gradually gaining more and
more acceptance among other fatigue analysis practices, hence the need for an
estimation of the actual surface stresses along fillet weld toes, has become
imperative. Towards this, different 2-D geometries are tested against stress
concentration factors developed at weld toes, which are calculated on the basis
of maximum in-plane principal stresses over nominal stresses in mode I pure
bending and pure tension respectively. Moreover, validation with corresponding
results from literature is provided. Finally, three different concepts for reducing
the maximum surface stresses are presented. The first one proposes grinding
of the weld toe area and formulation of an artificial U-notch or a part- circular
profile. The second one applies to non-penetrating welds and assumes the
existence of a root gap of a specific geometry which is related to the fatigue life
and stress concentration factor of the fillet weld joint. Last but not least, the
relatively recent concept of the variable radius notch is discussed, even though
it is applicable mostly to notched bodies, not weld joints.
Afterwards, a Linear Elastic Fracture Mechanics analysis of reference 2D fillet
weld model is demonstrated. A number of geometrical parameters considered
at previous stage for their impact on surface Stress Concentration levels at the
weld toe region, have been correlated to fatigue life benefits in terms of
increased number of stress cycles till failure.
An extensive analysis of 9 different T-butt weld joint geometries has been
provided in order to investigate how positively a possible SCF reduction can
affect the fatigue life of a weld joint. Essential geometric variations (weld angle,
length, toe radius, root slot) were considered in the 2D model. All calculated
benefits both in pure bending and pure tension cases have been reported
accordingly.
Based on a linear interpolation of the points scatter (SCF, N-cycles) both in
banding and tension, it was observed that a surface stress mitigation of 1%
could lead to 1,33 up to 2,5% fatigue life benefit in the range of SCF=2 – 2,5. It
is evident so far that the geometrical optimization of a weld joint in respect of
notch stress mitigation can be a powerful tool both in shipbuilding and
maintenance practice in the future. However, technically wise their application
may incur high initial costs of improved tools of welding and post welding
treatment and robots even though it would consist a cost effective solution in a
medium/long term basis.
Finally, the above process is followed by a reliability analysis of the most critical
geometrical parameters affecting the fatigue life of a fillet weld joint. Reliability
assessment results concerning medium, high and low cycle fatigue are provided
and a comparative analysis of each factor‟s impact on fatigue life has been
carried out.
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The application of modified linear elastic fracture mechanics (LEFM) and its implication for tear strength development of fibrous materialsZhang, Ziyang 06 November 2020 (has links)
No description available.
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Método dos elementos de contorno aplicado à análise de sólidos multi-fraturados / Boundary element method applied to analysis of multi-fractured bodiesLeonel, Edson Denner 03 March 2006 (has links)
Esse trabalho trata da análise de corpos multi-fraturados utilizando o método dos elementos de contorno. Este método numérico é conhecido por ser robusto e preciso neste tipo de problema e também por requerer pequeno esforço computacional na criação da malha de elementos para o crescimento das fissuras. Duas metodologias para a análise do comportamento das fissuras são consideradas. A primeira é a já consagrada metodologia dual. Por meio desta técnica equações integrais distintas são aplicadas às faces da fissura. Estas equações integrais são escritas em termos de deslocamentos e forças de superfície. A segunda metodologia é a que emprega a formulação singular onde a fissura é considerada como um vazio no domínio sendo as faces da fissura separadas por uma pequena distância. No tocante ao crescimento das fissuras foi desenvolvido um procedimento especial para a determinação da direção de crescimento das fissuras o qual mostrou-se muito eficiente levando a resultados precisos. O crescimento das fissuras é efetuado considerando o fator de intensidade de tensão atuante na extremidade de cada fissura. Dessa forma, as fissuras mais solicitadas apresentam maior comprimento de propagação tornando a análise mais realista. Os fatores de intensidade de tensão são calculados por meio de duas técnicas. A primeira é a já conhecida técnica de correlação de deslocamentos a qual relaciona os deslocamentos atuantes nas faces da fissura. Uma técnica alternativa é também utilizada a qual emprega o campo de tensões presente na extremidade da fissura. Após a determinação dos fatores de intensidade de tensão quatro diferentes teorias de interação de modos podem ser utilizadas para a determinação do ângulo de propagação. Foram analisadas estruturas sendo os resultados comparados aos previstos analiticamente e também numericamente. As respostas obtidas foram satisfatórias validando assim a metodologia proposta neste trabalho / This work deals with analysis of multi-fractured bodies using boundary element method. This numerical method is known to be robust and accurate in this kind of problem and by small computational effort to create elements mesh of crack growth. Two methodologies to analyze of crack behavior are considerate. The first is consecrated dual methodology. Through this technique different kind of integral equations are applied to crack boundaries. These integrals equations are written in displacements and traction variables. Second methodology is singular formulation. Through this technique crack is represented like a hole in body and the crack boundaries is separated by a small gap. For crack growth was created a special proceeding to determination crack growth direction. This method is very efficient and your results are accurate. Crack growth is made through the stress intensity factor performed in crack tip. Then the cracks more requested going to propagate with a larger lengths growth turning this model very realistic. The stress intensity factors are calculated through two techniques in this work. First is the known correlation displacement technique which related displacement in crack boundaries. An alternative technique is also used which consider stress field in crack tip. After determination of stress intensity factors four different theories are used to calculate the crack growth angle. In this work were analyzed structures with results are compared with analytical and numerical answers. The results obtained went very satisfactory validating the methodology proposed
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A natural neighbours method based on Fraeijs de Veubeke variational principleLi, Xiang 02 July 2010 (has links)
A Natural nEighbours Method (NEM) based on the FRAEIJS de VEUBEKE (FdV) variational
principle is developed in the domain of 2D infinitesimal transformations.
This method is firstly applied to linear elastic problems and then is extended to materially
nonlinear problems and problems of linear elastic fracture mechanics (LEFM).
In all these developments, thanks to the FdV variational principle, the displacement field, the
stress field, the strain field and the support reaction field are discretized independently.
In the spirit of the NEM, nodes are distributed in the domain and on its contour and the
corresponding Voronoi cells are constructed.
In linear elastic problems the following discretization hypotheses are used:
1. The assumed displacements are interpolated between the nodes with Laplace functions.
2. The assumed support reactions are constant over each edge of Voronoi cells on which
displacements are imposed.
3. The assumed stresses are constant over each Voronoi cell.
4. The assumed strains are constant over each Voronoi cell.
The degrees of freedom linked with the assumed stresses and strains can be eliminated at the level
of the Voronoi cells so that the final equation system only involves the nodal displacements and
the assumed support reactions.
The support reactions can be further eliminated from the equation system if the imposed support
conditions only involve constant imposed displacements (in particular displacements imposed to
zero) on a part of the solid contour, finally leading to a system of equations of the same size as in
a classical displacement-based method.
For the extension to materially non linear problems, similar hypotheses are used. In particular, the
velocities are interpolated by Laplace functions and the strain rates are assumed to be constant in
each Voronoi cell.
The final equations system only involves the nodal velocities. It can be solved step by step by time
integration and Newton-Raphson iterations at the level of the different time steps.
In the extension of this method for LEFM, a node is located on each crack tip. In the Voronoi cells
containing the crack tip, the stress and the strain discretization includes not only a constant term
but also additional terms corresponding to the solutions of LEFM for modes 1 and 2.
In this approach, the stress intensity coefficients are obtained as primary variables of the solution.
The final equations system only involves the nodal displacements and the stress intensity
coefficients.
Finally, an eXtended Natural nEighbours Method (XNEM) is proposed in which the crack is
represented by a line that does not conform to the nodes or the edges of the cells.
Based on the hypotheses used in linear elastic domain, the discretization of the displacement field
is enriched with Heaviside functions allowing a displacement discontinuity at the level of the
crack.
In the cells containing a crack tip, the stress and strain fields are also enriched with additional
terms corresponding to the solutions of LEFM for modes 1 and 2.
The stress intensity coefficients are also obtained as primary variables of the solution.
A set of applications are performed to evaluate these developments.
The following conclusions can be drawn for all cases (linear elastic, nonlinear, fracture
mechanics).
In the absence of body forces, the numerical calculation of integrals over the area of the
domain is avoided: only integrations on the edges of the Voronoi cells are required, for
which classical Gauss numerical integration with 2 integration points is sufficient to pass
the patch test.
The derivatives of the nodal shape functions are not required in the resulting formulation.
The patch test can be successfully passed.
Problems involving nearly incompressible materials can be solved without
incompressibility locking in all cases.
The numerical applications show that the solutions provided by the present approach
converge to the exact solutions and compare favourably with the classical finite element
method. / Une méthode des éléments naturels (NEM) basée sur le principe variationnel de FRAEIJS de
VEUBEKE (FdV) est développée dans le domaine des transformations infinitésimales 2D.
Cette méthode est dabord appliquée aux problèmes élastiques linéaires puis est étendue aux
problèmes matériellement non linéaires ainsi quà ceux de la mécanique de la rupture élastique
linéaire (LEFM).
Dans tous ces développements, grâce au principe variationnel de FdV, les champs de
déplacements, contraintes, réformations et réactions dappui sont discrétisés de façon
indépendante.
Dans lesprit de la NEM, des noeuds sont distribués dans le domaine et sur son contour et les
cellules de Voronoi associées sont construites.
En domaine élastique linéaire, les hypothèses de discrétisation sont les suivantes :
1. Les déplacements sont interpolés entre les noeuds par des fonctions de Laplace.
2. Les réactions dappui sont supposées constantes sur chaque côté des polygones de Voronoi
le long desquels des déplacements sont imposés.
3. Les contraintes sont supposées constantes sur chaque cellule de Voronoi.
4. Les déformations sont supposées constantes sur chaque cellule de Voronoi.
Les degrés de liberté associés aux hypothèses sur les contraintes et les déformations peuvent être
éliminées au niveau des cellules de Voronoi de sorte que le système déquations final nimplique
que les déplacement nodaux et les réactions dappui supposées.
Ces dernières peuvent également être éliminées de ce système déquations si les conditions
dappui nimposent que des déplacements constants (en particulier égaux à zéro) sur une partie du
contour du domaine étudié, ce qui conduit à un système déquations de même taille que dans une
approche basée sur la discrétisation des seuls déplacements.
Pour lextension aux problèmes matériellement non linéaires, des hypothèses similaires sont
utilisées. En particulier, les vitesses sont interpolées par des fonctions de Laplace et déformations
sont supposées constantes sur chaque cellule de Voronoi.
Le système déquations final nimplique que les vitesses nodales. Il peut être résolu pas à pas par
intégration temporelle et itérations de Newton-Raphson à chaque pas de temps.
Pour lextension de cette méthode aux problèmes de LEFM, un noeud est localisé à chaque pointe
de fissure. Dans les cellules de Voronoi correspondantes, la discrétisation des contraintes et des
déformations contient non seulement un terme constant mais aussi des termes additionnels
correspondant aux solutions de la LEFM pour les modes 1 et 2.
Avec cette approche, les coefficients dintensité de contraintes constituent des variables primaires
de la solution. Le système déquations final ne contient que les déplacements nodaux et les
coefficients dintensité de contraintes.
Finalement, une méthode des éléments naturels étendue (XNEM) est proposée dans laquelle la
fissure est représentée par une ligne indépendante des noeuds ou des côtés des cellules de Voronoi.
La discrétisation utilisée en domaine élastique linéaire est enrichie par des fonctions de Heaviside
qui autorisent une discontinuité des déplacements au niveau de la fissure.
Dans les cellules contenant une pointe de fissure, les contraintes et les déformations sont aussi
enrichies par des termes additionnels correspondant aux solutions de la LEFM pour les modes 1 et
2.
Ici aussi, les coefficients dintensité de contraintes constituent des variables primaires de la
solution.
Une série dapplications numériques sont réalisées afin dévaluer ces développements.
Les conclusions suivantes peuvent être tirées. Elles sappliquent à tous les cas (élastique linéaire,
non linéaire, mécanique de la rupture) :
En labsence de force volumique, le calcul numérique dintégrales sur laire du domaine
est évité : seules sont nécessaires des intégrales numériques sur les côtés des cellules de
Voronoi. Lutilisation de 2 points de Gauss suffit pour passer le patch test.
Les dérivées des fonctions dinterpolation nodales ne sont pas nécessaires dans cette
formulation.
La formulation passe le patch test.
Les problèmes impliquant des matériaux quasi incompressibles sont résolus sans
verrouillage.
Les applications numériques montrent que les solutions fournies par lapproche
développée convergent vers les solutions exactes et se comparent favorablement avec
celles de la méthode des éléments finis.
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Método dos elementos de contorno aplicado à análise de sólidos multi-fraturados / Boundary element method applied to analysis of multi-fractured bodiesEdson Denner Leonel 03 March 2006 (has links)
Esse trabalho trata da análise de corpos multi-fraturados utilizando o método dos elementos de contorno. Este método numérico é conhecido por ser robusto e preciso neste tipo de problema e também por requerer pequeno esforço computacional na criação da malha de elementos para o crescimento das fissuras. Duas metodologias para a análise do comportamento das fissuras são consideradas. A primeira é a já consagrada metodologia dual. Por meio desta técnica equações integrais distintas são aplicadas às faces da fissura. Estas equações integrais são escritas em termos de deslocamentos e forças de superfície. A segunda metodologia é a que emprega a formulação singular onde a fissura é considerada como um vazio no domínio sendo as faces da fissura separadas por uma pequena distância. No tocante ao crescimento das fissuras foi desenvolvido um procedimento especial para a determinação da direção de crescimento das fissuras o qual mostrou-se muito eficiente levando a resultados precisos. O crescimento das fissuras é efetuado considerando o fator de intensidade de tensão atuante na extremidade de cada fissura. Dessa forma, as fissuras mais solicitadas apresentam maior comprimento de propagação tornando a análise mais realista. Os fatores de intensidade de tensão são calculados por meio de duas técnicas. A primeira é a já conhecida técnica de correlação de deslocamentos a qual relaciona os deslocamentos atuantes nas faces da fissura. Uma técnica alternativa é também utilizada a qual emprega o campo de tensões presente na extremidade da fissura. Após a determinação dos fatores de intensidade de tensão quatro diferentes teorias de interação de modos podem ser utilizadas para a determinação do ângulo de propagação. Foram analisadas estruturas sendo os resultados comparados aos previstos analiticamente e também numericamente. As respostas obtidas foram satisfatórias validando assim a metodologia proposta neste trabalho / This work deals with analysis of multi-fractured bodies using boundary element method. This numerical method is known to be robust and accurate in this kind of problem and by small computational effort to create elements mesh of crack growth. Two methodologies to analyze of crack behavior are considerate. The first is consecrated dual methodology. Through this technique different kind of integral equations are applied to crack boundaries. These integrals equations are written in displacements and traction variables. Second methodology is singular formulation. Through this technique crack is represented like a hole in body and the crack boundaries is separated by a small gap. For crack growth was created a special proceeding to determination crack growth direction. This method is very efficient and your results are accurate. Crack growth is made through the stress intensity factor performed in crack tip. Then the cracks more requested going to propagate with a larger lengths growth turning this model very realistic. The stress intensity factors are calculated through two techniques in this work. First is the known correlation displacement technique which related displacement in crack boundaries. An alternative technique is also used which consider stress field in crack tip. After determination of stress intensity factors four different theories are used to calculate the crack growth angle. In this work were analyzed structures with results are compared with analytical and numerical answers. The results obtained went very satisfactory validating the methodology proposed
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Crack propagation in concrete dams driven by internal water pressureSohrabi, Maria, Sanchez Loarte, José January 2017 (has links)
Concrete structures are in general expected to be subjected to cracking during its service life. This is the reason why concrete is reinforced, where the reinforcement is only activated after cracks occur. However, cracks may be a concern in large concrete structures, such as dams, since it may result in reduced service life. The underlying mechanisms behind crack formations are well known at present day. On the other hand, information concerning the crack condition over time and its influence on the structure is limited, such as the influence of water pressure within the cracks. The aim of this project is to study crack propagation influenced by water pressure and to define an experimental test setup that allows for crack propagation due to this load. Numerical analyses have been performed on an initial cracked specimen to study the pressure along the crack propagation. The finite element method has been used as the numerical analysis tool, through the use of the software ABAQUS. The finite element models included in these studies are based on linear or nonlinear material behavior to analyze the behavior during a successively increasing load. The numerical results show that a crack propagates faster if the water is keeping up with the crack extension, i.e. lower water pressure is required to open up a new crack. When the water does not have time to develop within the crack propagation, more pressure is required to open up a new crack. The experimental results show that the connection between the water inlet and the specimen is heavily affected by the bonding material. In addition, concrete quality and crack geometry affects the propagation behavior.
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A Numerical Based Determination of Stress Intensity Factors for Partially Cracked Flexural I-shaped Cross-sectionsSomeshwara Korachar, Eshwari 19 April 2019 (has links)
The AASHTO LRFD design specifications and the AASHTO manual for bridge evaluation are consistently revised using knowledge of previous bridge failures. Although modern steel structures are designed to resist fatigue cracking from service loads, cracks in the tension flanges of steel bridge girders have been observed as a result of stress concentrations, design errors, welding quality control, and vehicular impacts. Cracks can grow in size with time and active cyclic live loads and may result in a member fracture. Fracture is a dangerous limit state which occurs with little to no warning. One method to quantify the stress field in the vicinity of a crack tip is by calculating the Stress Intensity Factor (SIF) around the crack tip. Finding SIFs for a cracked geometry may help an engineer to determine the fracture potential based on crack dimensions found during the inspection. Rolled I-beam and steel plate girders are extensively used as bridge superstructure members to efficiently carry live loads. This research was focused on determining Stress Intensity Factors (SIFs) of partially cracked I-sections using Finite Element Analysis. Two different tension flange crack profiles were studied: edge cracks, and full-width cracks. The SIF solutions were further used to study the fracture behavior and stress redistribution in the partially cracked flexural I-shaped members. / Master of Science / Steel is one of the fundamental materials used in the construction of bridge structures, and steel girder bridges are one of the most common types of bridge structures seen in the United States. Past bridge failures have helped engineers to understand shortcomings in design specifications, and AASHTO codes have been developed and revised over the years to reflect an improved understanding and evolution of engineering behavior. Engineers must make sure that a design is robust enough for functional use of the component during its service life. It is also equally important to understand the potential chances of failure and make the structure strong enough to overcome any failure mechanisms. Fracture is one structural failure mode which occurs with little to no warning and hence is very dangerous. One efficient way to quantify the stress field in the vicinity of a crack tip is by calculating the Stress Intensity Factor (SIF) around a crack tip. Fracture literature is available which describes different methods of determining SIFs for cracked members. However, there are no solutions available to find a SIF of a partially cracked flexural I-shaped members. This research was focused on determining Stress Intensity Factors and studying the fracture behavior of partially cracked I-sections using Finite Element Analysis. The resulting SIF solutions were further used to study the fracture behavior and stress redistribution in partially cracked flexural I-shaped members.
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A peridynamic model for sleeved hydraulic fractureVan Der Merwe, Carel Wagener 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Current numerical methods in the eld of hydraulic fracturing are based mainly on
continuum methods, such as the Finite Element Method (FEM) and the Boundary Element
Method (BEM). These methods are governed by Linear Elastic Fracture Mechanics
(LEFM) criteria, which su er from the inherent
aw of a non-physical stress representation
at the fracture tip. In response to this, a non-local method is proposed, namely
the peridynamic theory, to model sleeved hydraulic fracture. A 2D implicit quasi-static
ordinary state based peridynamic formulation is implemented on various benchmark
problems, to verify the ability to capture constitutive behaviour in a linear elastic solid,
as well as, the quanti cation of adverse e ects on the accuracy of the displacement solution,
due to the nature of the non-local theory. Benchmark tests consist of a plate in
tension, where convergence to the classical displacement solution, non-uniform re nement
and varying cell sizes are tested, as well as, a thick walled cylinder with internal
pressure, where three di erent loading techniques are tested. The most accurate loading
technique is applied to the sleeved fracture model, in order to simulate fracture initiation
and propagation. This model is then veri ed and validated by using the Rummel &
Winter hydraulic fracturing model and experimental results, respectively. Displacement
error minimisation methods are implemented and as a result, the displacement solutions
for a plate in tension converges to the analytical solution, while the thick walled cylinder
solutions su er from inaccuracies due to an applied load on an irregularly discretized
region. The fracture initiation test captures the fracture tip behaviour of the Rummel
& Winter model and the fracture propagation test show good correlation with experimental
results. This research shows that the peridynamic approach to sleeved hydraulic
fracture can yield a realistic representation of fracture initiation and propagation, however,
further research is needed in the area of a pressure load application on a solid using
the peridynamic approach. / AFRIKAANSE OPSOMMING: Huidige numeriese metodes in die veld van hidrouliese breking is hoofsaaklik gebaseer
op kontinuum metodes, soos die Eindige Element Metode (EEM) en die Rand Element
Metode (REM). Hierdie metodes word beheer deur Linie^ere Elastiese Breukmeganika
(LEB) kriteria, wat ly aan die inherente gebrek van 'n nie- siese voorstelling van die
spanning by die fraktuur punt. Om hierdie probleme aan te spreek, word 'n nie-lokale
metode voorgestel, naamlik die peridinamiese teorie, om gehulsde hidrouliese breking
te modelleer. 'n 2D implisiete kwasi-statiese ordin^ere toestand gebaseerde peridinamika
formulering word ge mplimenteer op verskeie norm probleme, om te veri eer of dit oor
die vermo e beskik om die konstitutiewe gedrag van 'n linie^ere elastiese soliede materiaal
te modeleer, asook die kwanti sering van nadelige e ekte op die verplasings oplossing as
gevolg van die natuur van die nie-lokale teorie. Normtoetse bestaan uit 'n plaat in trek
spanning, waar konvergensie na die klassieke verplasings oplossing, nie-uniforme verfyning
en vari^eerende sel groottes getoets word, asook 'n dikwandige silinder onder interne
druk, waar drie verskillende belasting aanwendingstegnieke getoets word. Die mees akkurate
belasting aanwendingstegniek word dan gebruik in die gehulsde hidrouliese breking
model, om fraktuur aanvangs en uitbreiding na te boots. Die model word dan geveri-
eer deur die Rummel & Winter hidrouliese breking model en eksperimentele resultate,
onderskeidelik. Fout minimering metodes word toegepas en as 'n resultaat, konvergeer
die verplasing oplossing vir die plaat na die analitiese oplossing, terwyl die oplossing
van die dikwandige silinder onakuraathede toon as gevolg van 'n toegepaste belasting
op 'n onre elmatig gediskretiseerde gebied. Die modellering van die fraktuur inisi ering
by die fraktuur punt, stem goed ooreen met die Rummel en Winter voorspelling en die
fraktuur uitbreiding stem goed ooreen met eksperimentele resultate. Hierdie navorsing
toon dat die peridinamiese benadering tot gehulsde hidrouliese breking wel die fraktuur
inisi ering en uitbreiding realisties kan modelleer, maar nog navorsing word wel benodig
in die area waar 'n druk belasting op 'n peridinamiese soliede model toegepas word.
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