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Omatuku, Emmanuel Ngongo. "Phase field modeling of dynamic brittle fracture at finite strains". Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30172.
Pełny tekst źródłaSchlueter, Alexander [Verfasser], i Charlotte [Akademischer Betreuer] Kuhn. "Phase Field Modeling of Dynamic Brittle Fracture / Alexander Schlueter ; Betreuer: Charlotte Kuhn". Kaiserslautern : Technische Universität Kaiserslautern, 2018. http://d-nb.info/116213397X/34.
Pełny tekst źródłaLi, Tianyi. "Gradient-damage modeling of dynamic brittle fracture : variational principles and numerical simulations". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX042/document.
Pełny tekst źródłaIn civil engineering, mechanical integrity of the reinforced concrete structures under severe transient dynamic loading conditions is of paramount importance for safety and calls for an accurate assessment of structural behaviors in presence of dynamic crack propagation. In this work, we focus on the constitutive modeling of concrete regarded as an elastic-damage brittle material. The strain localization evolution is governed by a gradient-damage approach where a scalar field achieves a smeared description of dynamic fracture phenomena. The contribution of the present work is both theoretical and numerical. We propose a variationally consistent formulation of dynamic gradient damage models. A formal definition of several energy release rate concepts in the gradient damage model is given and we show that the dynamic crack tip equation of motion is governed by a generalized Griffith criterion. We then give an efficient numerical implementation of the model based on a standard finite-element spatial discretization and the Newmark time-stepping methods in a parallel computing framework. Simulation results of several problems are discussed both from a computational and physical point of view. Different damage constitutive laws and tension-compression asymmetry formulations are compared with respect to their aptitude to approximate brittle fracture. Specific properties of the dynamic gradient damage model are investigated for different phases of the crack evolution: nucleation, initiation, propagation, arrest, kinking and branching. Comparisons with experimental results are also performed in order to validate the model and indicate its further improvement
Zhai, Xinyuan. "Crack propagation in elastic media with anisotropic fracture toughness : experiments and numerical modeling". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAE010.
Pełny tekst źródłaAdditive manufacturing is receiving increasing attention due to its advantages in terms of modelling flexibility and allowing to easily design complex micro-structures. Through the manipulation of the printing strategy, we observed that fused deposition of polycarbonate can result in printed samples showcasing a distinct anisotropic behavior in fracture toughness, all the while retaining isotropic properties in elasticity.This thesis is dedicated to investigating fracture behavior within isotropic elastic media with anisotropic fracture toughness. The approach involves a combination of fracture experiments and numerical simulations. In the experimental part, we examine crack propagation under various loading conditions using diverse sample geometries, encompassing both Mode I and Mode I+II loading condition. In the numerical part, we adopt the phase-field modeling of brittle fracture based on a variational approach, using experimental data for calibrating and identification of the numerical parameters. Through these comprehensive methodologies, our objective is to foster a deeper comprehension of the interplay between printing patterns and the selection of crack paths. This understanding holds significant implications for guiding and controlling crack propagation in additive manufacturing-produced components. Besides, we adopted the classical based criteria Generalized Maximum Energy Release Rate to enhance our understanding of crack path selection and the relevant critical force.In the last part of this thesis, we presents some preliminary investigations regarding the potential emergence of Zig-Zag crack patterns in 3D printed specimens. Additionally, we delve extensively into the fracture behavior of printed specimens under cyclic loading, offering a comprehensive comparison between experimental observations and numerical forecasts
Cheng, Zifeng. "Modelling Brittle Fractures with Finite Elements: A Time-independent Phase-field Model". Thesis, Faculty of Engineering, School of Civil Engineering, 2020. https://hdl.handle.net/2123/29350.
Pełny tekst źródłaDeogekar, Sai Sharad. "A Computational Study of Dynamic Brittle Fracture Using the Phase-Field Method". University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439455086.
Pełny tekst źródłaTanne, Erwan. "Variational phase-field models from brittle to ductile fracture : nucleation and propagation". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX088/document.
Pełny tekst źródłaPhase-field models, sometimes referred to as gradient damage, are widely used methods for the numerical simulation of crack propagation in brittle materials. Theoretical results and numerical evidences show that they can predict the propagation of a pre-existing crack according to Griffith’s criterion. For a one- dimensional problem, it has been shown that they can predict nucleation upon a critical stress, provided that the regularization parameter is identified with the material’s internal characteristic length.In this work, we draw on numerical simulations to study crack nucleation in commonly encountered geometries for which closed-form solutions are not available. We use U- and V-notches to show that the nucleation load varies smoothly from the one predicted by a strength criterion to the one of a toughness criterion when the strength of the stress concentration or singularity varies. We present validation and verification of numerical simulations for both types of geometries. We consider the problem of an elliptic cavity in an infinite or elongated domain to show that variational phase field models properly account for structural and material size effects.In a second movement, this model is extended to hydraulic fracturing. We present a validation of the model by simulating a single fracture in a large domain subject to a control amount of fluid. Then we study an infinite network of pressurized parallel cracks. Results show that the stimulation of a single fracture is the best energy minimizer compared to multi-fracking case. The last example focuses on fracturing stability regimes using linear elastic fracture mechanics for pressure driven fractures in an experimental geometry used in petroleum industry which replicates a situation encountered downhole with a borehole called burst experiment.The last part of this work focuses on ductile fracture by coupling phase-field models with perfect plasticity. Based on the variational structure of the problem we give a numerical implementation of the coupled model for parallel computing. Simulation results of a mild notch specimens are in agreement with the phenomenology of ductile fracture such that nucleation and propagation commonly reported in the literature
Abdollahi, Amir. "Phase-field modeling of fracture in ferroelectric materials". Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/285833.
Pełny tekst źródłaLos materiales ferroeléctricos poseen únicas propiedades electro-mecánicas y por eso se utilizan para los micro-dispositivos como sensores, actuadores y transductores. No obstante, debido a la fragilidad intrínseca de los ferroeléctricos, el diseño óptimo de los dispositivos electro-mecánicos es altamente dependiente de la comprensión del comportamiento de fractura en estos materiales. Los procesos de fractura en ferroeléctricos son notoriamente complejos, sobre todo debido a las interacciones entre campos de tensión y eléctricos y los fenómenos localizados en zona de fractura (formación y evolución de los dominios de las diferentes variantes cristalográficas). Los modelos de campo de fase son particularmente útiles para un problema tan complejo, ya que una sola ecuación diferencial parcial que gobierna el campo de fase lleva a cabo a la vez (1) el seguimiento de las interfaces de una manera suave (grietas, paredes de dominio) y (2) la modelización de los fenómenos interfaciales como las energías de la pared de dominio o las condiciones de las caras de grieta. Tal modelo no tiene ninguna dificultad, por ejemplo en la descripción de la nucleación de los dominios y las grietas o la ramificación y la fusión de las grietas. Además, la naturaleza variacional de estos modelos facilita el acoplamiento de múltiples físicas (campos eléctricos y mecánicos en este caso). La principal aportación de esta tesis es la propuesta de un modelo campo de fase para la simulación de la formación y evolución de la microestructura y la nucleación y propagación de grietas en materiales ferroeléctricos. El modelo aúna dos modelos de campo de fase para la fractura frágil y para la formación de dominios ferroeléctricos. La aplicación de elementos finitos a la teoría es descrita. Las simulaciones muestran las interacciones entre la microestructura y la fractura del bajo cargas mecánicas y electro-mecánicas. Otro de los objetivos de esta tesis es la codificación de diferentes condiciones de contorno de grieta porque estas condiciones afectan en gran medida el comportamiento de la fractura de ferroeléctricos. La imposición de estas condiciones se discuten y se comparan con los resultados de modelos clasicos para validar los modelos propuestos. Las simulaciones muestran los efectos de diferentes condiciones, cargas electro-mecánicas y medios que llena el hueco de la grieta en la propagación de las fisuras y la microestructura del material. En un tercer paso, el modelo se modifica mediante la introducción de una condición que representa el comportamiento asimétrico en tensión y compresión. El modelo modificado hace posible explicar el crecimiento de la grieta anisotrópica en ferroeléctricos. Este modelo también se utiliza para el análisis de la fractura de los actuadores ferroeléctricos, lo que demuestra el potencial del modelo para su futura aplicación. El modelo se extiende también a policristales mediante la introducción de microestructuras policristalinas realistas en el modelo. Modos de fractura inter y trans-granulares de propagación se observan en las simulaciones. Por último y para completar, la teoría del campo de fase se extiende para la simulación de las grietas conductivas y algunas simulaciones preliminares también se realizan en tres dimensiones. Principales características del fenómeno de la propagación de la grieta predicho por las simulaciones de esta tesis se comparan directamente con las observaciones experimentales.
Parrinello, Antonino. "A rate-pressure-dependent thermodynamically-consistent phase field model for the description of failure patterns in dynamic brittle fracture". Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:c6590f4f-f4e2-40e3-ada1-49ba35c2a594.
Pełny tekst źródłaLee, Ji Soo. "Time-Dependent Crack Growth in Brittle Rocks and Field Applications to Geologic Hazards". Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/193784.
Pełny tekst źródłaBhowmick, Sauradeep. "Advanced Smoothed Finite Element Modeling for Fracture Mechanics Analyses". University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623240613376967.
Pełny tekst źródłaNigro, Claudio F. "Phase field modeling of flaw-induced hydride precipitation kinetics in metals". Licentiate thesis, Malmö högskola, Institutionen för materialvetenskap och tillämpad matematik (MTM), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-7787.
Pełny tekst źródłaGavagnin, Claudio. "Modeling and computation of cracking in multiphase porous media with the phase-field approach". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3427308.
Pełny tekst źródłaLo sviluppo di modelli matematici e numerici per lo studio della frattura nei mezzi porosi è motivato da numerose applicazioni nel mondo reale. In particolare, lo studio della frattura con la tecnica del phase-filed, basata sulla regolarizzazione della formulazione variazionale della teoria di Griffith, sembra essere una delle più promettenti, grazie alla sua abilità di modellare fenomeni complessi, come la formazione e la ramificazione di fratture, a preservare la continuità del campo di spostamenti. La maggior parte dei modelli phase-field presenti in letteratura sono principalmente orientati allo studio della frattura in mezzi porosi saturi. D'altro canto, alcuni fenomeni, come la formazione di fratture in argille durante un processo di essicazione, indicano l'importanza di estendere questi modelli in condizione di parziale saturazione, tenendo in considerazione la possibile influenza del flusso della fase gassosa sul comportamento meccanico dello scheletro solido e, di conseguenza, sul processo di formazione e evoluzione della frattura. Lo scopo di questa tesi è la formulazione di un modello numerico agli elementi finiti per lo studio, con la tecnica del phase-field, della frattura in mezzi porosi trifase, in cui si considerino sia il flusso d'acqua che il flusso dell'aria all'interno del mezzo. Particolare attenzione è rivolta ad un approfondimento di alcune problematiche numeriche che tale modellazione comporta, come gli errori nella conservazione della massa della fase liquida e il locking numerico dovuto ad un eccesso di rigidezza volumetrica, quando lo split volumetrico-deviatorico dell'energia viene utilizzato nel modello phase-field. In particolare, vengono proposte e testate attraverso varie applicationi numeriche una nuova formulazione conservativa che tenga conto della deformabilità dello scheletro solido, e una nuova stabilizzazione per la formulazione mista del modello phase-field per la frattura in mezzi porosi saturi. Nell'ultima parte la discretizzazione agli elementi finiti del modello trifase proposto viene derivata, e applicata alla simulazione numerica di due problemi di essicazione, con l'obiettivo di studiare l'influenza dell'equazione di bilancio dell'aria sullo sviluppo di fratture nel mezzo poroso.
Cajuhi, Tuanny Verfasser], Lorenzis Laura [Akademischer Betreuer] De i Pietro [Akademischer Betreuer] [Lura. "Fracture in porous media : phase-field modeling, simulation and experimental validation / Tuanny Cajuhi ; Laura De Lorenzis, Pietro Lura". Braunschweig : Technische Universität Braunschweig, 2019. http://d-nb.info/1180601521/34.
Pełny tekst źródłaSridhar, Ashish [Verfasser], i Marc-André [Akademischer Betreuer] Keip. "Phase-field modeling of microstructure and fracture evolution in magneto-electro-mechanics / Ashish Sridhar ; Betreuer: Marc-André Keip". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1232727903/34.
Pełny tekst źródłaAldakheel, Fadi [Verfasser], i Christian [Akademischer Betreuer] Miehe. "Mechanics of nonlocal dissipative solids : gradient plasticity and phase field modeling of ductile fracture / Fadi Aldakheel ; Betreuer: Christian Miehe". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118370228/34.
Pełny tekst źródłaSchänzel, Lisa-Marie [Verfasser], i Christian [Akademischer Betreuer] Miehe. "Phase field modeling of fracture in rubbery and glassy polymers at finite thermo-viscoelastic deformations / Lisa-Marie Schänzel. Betreuer: Christian Miehe". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1069107409/34.
Pełny tekst źródłaGoswami, Somdatta [Verfasser], Timon [Akademischer Betreuer] Rabczuk, Stephane [Gutachter] Bordas i Magd Abel [Gutachter] Wahab. "Phase field modeling of fracture with isogeometric analysis and machine learning methods / Somdatta Goswami ; Gutachter: Stephane Bordas, Magd Abel Wahab ; Betreuer: Timon Rabczuk". Weimar : Bauhaus-Universität Weimar, 2021. http://d-nb.info/122878924X/34.
Pełny tekst źródłaMsekh, Mohammed Abdulrazzak Verfasser], Timon [Akademischer Betreuer] Rabczuk, Lorenzis Laura [Gutachter] De i Tom [Gutachter] [Lahmer. "Phase Field Modeling for Fracture with Applications to Homogeneous and Heterogeneous Materials / Mohammed Abdulrazzak Msekh ; Gutachter: Laura De Lorenzis, Tom Lahmer ; Betreuer: Timon Rabczuk". Weimar : Bauhaus-Universität Weimar, 2017. http://d-nb.info/1135592950/34.
Pełny tekst źródłaMsekh, Mohammed Abdulrazzak Verfasser], Timon [Akademischer Betreuer] [Rabczuk, Lorenzis Laura Gutachter] De i Tom [Gutachter] [Lahmer. "Phase Field Modeling for Fracture with Applications to Homogeneous and Heterogeneous Materials / Mohammed Abdulrazzak Msekh ; Gutachter: Laura De Lorenzis, Tom Lahmer ; Betreuer: Timon Rabczuk". Weimar : Bauhaus-Universität Weimar, 2017. http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170615-32291.
Pełny tekst źródłaRiad, Soukaina. "Vers une modélisation de la corrosion sous contrainte assistée par l'irradiation du superalliage 718". Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0039.
Pełny tekst źródłaInconel 718 alloy is renowned for having excellent corrosion resistance, very high mechanical strength and good resistance to irradiation. Thus, it is a material of choice within a nuclear power reactor for parts subjected to extreme stresses (springs, retaining systems,...). However, failures in service have been observed in this material under irradiationassisted stress corrosion cracking phenomenon. This thesis aims to bring new elements of understanding of this complex phenomenon from the point of view of numerical modeling. The stress corrosion cracking process is modeled by the phase field fracture method. A unified implementation, able to deal with inter and intergranular fracture, is proposedand allows to couple efficiently different scales of work (from continuous medium to polycrystal) and different physics (mechanics of continuous and generalized media and internal oxidation). This modeling allows to propose simulations of the complex stages of stress corrosion cracking, namely initiation, coalescence and propagation
Borden, Michael Johns. "Isogeometric analysis of phase-field models for dynamic brittle and ductile fracture". Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6113.
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(9312344), Xiaorong Cai. "PHASE FIELD MODELING OF MICROSTRUCTURE EVOLUTION IN CRYSTALLINE MATERIALS". Thesis, 2020.
Znajdź pełny tekst źródłaThe material responses and the deformation pattern of crystals are strongly influ- enced by their microstructure, crystallographic texture and the presence of defects of various types.
In electronics, Sn coatings are widely used in circuits to protect conductors, reduce oxidation and improve solderability. However, the spontaneous growth of whiskers in Sn films causes severe system failures. Based on extensive experimental results, whiskers are observed to grow from surface grains with shallow grain boundaries. The underlying mechanism for these surface grains formation is crucial to predict potential whisker sites. A phase field model is coupled with a single crystal plasticity model and applied to simulate the grain boundary migration as well as the grain rotation process in Sn thin film, which are two possible mechanisms for surface grain formation. The grain boundary migration of three columnar grains is modeled and no surface grain is formed due to large plastic dissipation. In polycrystal Sn thin film, the nucleation of subgrains with shallow grain boundaries is observed for certain grain orientations on the film surface and the location of which corresponds to the regions with high strain energy density. From these simulations, it can be concluded that the grain rotation is the mechanism for whisker grain formation and the nucleated subgrains may be the potential whisker sites.
Sn-based solders are also widely used in electronics packaging. The reliability and the performance of SAC (Sn-Ag-Cu) solders are of key importance for the miniaturiza- tion of electronics. The interfacial reaction between Cu substrates and Sn-based sol- ders forms two types of brittle intermetallic compounds (IMCs), Cu6Sn5 and Cu3Sn.
During the operation, the interconnecting solders usually experience thermal loading
and electric currents. These environmental conditions result in the nucleation of voids
in Cu3Sn layer and the growth of the IMCs. A phase field damage model is applied
to model the fracture behavior in Cu/Sn system with different initial void densities
and different Cu3Sn thickness. The simulation results show the fracture location is
dependent on the Cu3Sn thickness and the critical stress for fracture can be increased
by lowering the void density and Cu3Sn thickness.
In alloys, the stacking fault energy varies with the local chemical composition. The effects of the stacking fault energy fluctuation on the strengthening of alloys are studied using phase field dislocation method (PFDM) simulations that model the evolution of partial dislocations in materials at zero temperature. Some examples are shown to study the dependency of the yield stress on the stacking fault energy, the decorrelation of partial dislocations in the presence of impenetrable and penetrable particles. Simulations of the evolution of partial dislocations in a stacking fault energy landscape with local fluctuations are presented to model the responses of high entropy alloys. A strong size dependency is observed with a maximum strength when the mean region size approaches the average equilibrium stacking fault width. The strength of high entropy alloys could be improved by controlling the disorder in the chemical misfit.
Arriaga, e. Cunha Miguel Torre do Vale. "Stability Analysis of Metals Capturing Brittle and Ductile Fracture through a Phase Field Method and Shear Band Localization". Thesis, 2016. https://doi.org/10.7916/D8RX9HPR.
Pełny tekst źródłaMondal, Anirban. "A non-classical continuum approach to study the fragmentation of brittle solids". Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5930.
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