En el presente trabajo se expone el uso del agua salina y/o agua de mar como sustancia en la mejora de los parámetros geotécnicos del suelo no cohesivo, procedente de los distritos de Villa El Salvador, Chilca y el balneario de Asia al sur de Lima, indicando los efectos del agua salina sobre estos. Además, se presentan los resultados de este suelo sin adición de agua salina, que en adelante se considerará como condiciones iniciales; y el método de aplicación del agua salina, que en adelante se denominará condiciones finales, con el fin de observar cuál es su comportamiento y el efecto que dicha sustancia causa en este suelo. También se analizan algunos aspectos de este proceso, a través de los resultados obtenidos dentro del laboratorio, para, de esta manera, tener no solo una apreciación visual sino también evidencia y registro de lo realizado mediante equipos especializados. / This work presents the use of saline water or seawater as a substance in the geotechnical parameters improvement of the non-cohesive soil from the districts of Villa El Salvador, Chilca and The Asia bay in southern Lima, indicating the effects of saline water on these. In addition, the results of this soil are presented without the addition of saline water, which here in after are considered as final conditions, in order to observe what it’s behavior is and the effect that causes this substance on this soil. Also, some aspects of this process are analyzed, through the results obtained in the laboratory, to obtain, in this way, not only a visual appreciation but also the evidence and record of that has been done through specialized equipment. / Tesis

La modélisation de bassin est couramment utilisée pour décrire l’évolution des bassins sédimentaires à partir d’une reconstitution de leur histoire. Durant la modélisation des processus géologiques, les propriétés de transfert des sédiments peuvent changer significativement à cause de leur fracturation naturelle. La présence de ces fractures dans le bassin peut constituer des chemins préférentiels d’écoulement ou des barrières qui contrôlent les niveaux de surpressions, l’accumulation et la migration des hydrocarbures dans le milieu ainsi que la perméabilité du milieu. Dans l’industrie pétrolière et en particulier durant l’exploration, la connaissance de l’historique des processus de fracturation naturelle permet d’améliorer la prédiction des positions de réservoirs d’hydrocarbures dans le milieu ainsi que leurs propriétés. En profondeur les fractures s’amorcent dans les roches aux niveaux des discontinuités géométriques. Cependant, les chargements à l’origine de l’initiation de ces fractures restent mal connus. Dans les bassins sédimentaires, les propriétés mécaniques et géométriques de ces fractures sont directement reliées aux processus inhérents à leur formation. Elles peuvent dériver de certains processus comme par exemple le dépôt des sédiments, les chargements tectoniques ou le processus d’érosion. Le but de cette thèse est de fournir une amélioration de la caractérisation de l’amorçage des fractures dans la modélisation de bassin à partir d’un outil numérique de simulation de réseaux de fractures et de son évolution sous chargement hydromécanique. Au cours de la sédimentation, les matériaux enfouis subissent une augmentation de la contrainte verticale. Cette augmentation de la contrainte par sédimentation entraîne une compaction mécanique et une diminution de la porosité. La compaction mécanique qui dépend du taux de sédimentation et de la perméabilité des matériaux enfouis peut générer des surpressions importantes dans le bassin. Dès lors une compétition s’établie entre la dissipation de la surpression des fluides et la vitesse de sédimentation et peut conduire à l’amorçage de fractures. Ainsi, pour étudier analytiquement l’amorçage des fractures dans le bassin, un modèle synthétique géologique est proposé. La solution analytique de l’évolution de la pression et des contraintes dans ce contexte est obtenu en superposant deux problèmes de poroélasticités. L’analyse de la solution et d’un critère de fracturation serviront de base pour prédire l’amorçage et la propagation des fractures. Pour simuler la propagation et l’évolution des fractures, un modèle numérique comportant des chemins potentiels de fracturation uniformément repartis est mis au point dans le code de calcul par éléments finis Porofis. Les fractures sont modélisées par un modèle de joints cohésifs avec endommagement et l’écoulement est décrit à partir de loi de Poiseuille. Les effets du couplage hydromécanique dans les fractures et dans la matrice poreuse sur l’évolution dynamique de l’espacement des fractures pour des cas synthétiques typiques de la modélisation de bassin sont également étudiés / Basin modeling is commonly used to describe basin's evolution from a reconstruction of its history. During the geological processes modeling, the transfer properties of sediments can change significantly due to natural fracturing and therefore may constitute preferential flow paths or barrier that control hydrocarbons migration and accumulation. In petroleum industry, and especially for exploration, the knowledge of natural fracturing processes and history enhances the prediction of overpressures, potential location of hydrocarbon storage and matrix equivalent permeability. At significant depth, nucleation of fractures and initiation are triggered at existing defects, but the loads behind its initiation are unknown or poorly characterized. In sedimentary basin, fracture mechanical and geometrical properties are directly related to the processes from which it comes. Fracture initiation at depth can arise from by many processes such as deposition, tectonic and erosion processes. The aim of the thesis is to provide an improvement in the characterization of fracture initiation in basin modeling by using a numerical modeling of fracture network and its evolution under hydro mechanical loading. During sedimentation, buried rocks are subjected to an increase in vertical stress. This increase leads to a decrease of porosity that is commonly called mechanical compaction. Indeed, the mechanical compaction depending on its rate and on the permeability of the burden rocks, can induce significant overpressures. Thus, a competition is initiated between the dissipation of fluid overpressure and sedimentation rate, and may result in fracture initiation. For analytical study of fracture initiation, a synthetic geologic structure is used. The analytical solution analytical solution of the pressure and stresses in a sealing formation is proposed under sedimentation by superposing two problems of poroelasticity. This analytical solution and a fracturing criterion are used to predict the initiation and propagation of the fracture. The fracture propagation and growth are studied by numerical simulations based on a finite element code dedicated to fractured porous media called Porofis. The numerical model contains defects initially closed and homogeneously distributed. The fractures are modeled with a constitutive model undergoing damage and the flow is described by Poiseuille’s law. The effect of hydromechanical coupling on dynamicevolution of fracture spacing using synthetic geological structure for basin modeling are also studied

Bien que la maçonnerie en pierre soit une technique de construction ancestrale,le comportement mécanique de ce type de construction reste encore aujourd’hui méconnu.En conséquence, la réglementation concernant ces ouvrages est restrictive et considèredes marges de sécurité importantes, qui conduisent à un surdimensionnement de cetype de structure. Ce projet de recherche vise à développer un code de calcul adapté à l’étudede structures maçonnées, utilisable en bureau d’études afin d’aider les ingénieurs qui nepossèdent pas d’outils adaptés aux ouvrages maçonnés sur lesquels s’appuyer.Le logiciel de calcul aux éléments discrets LMGC90 a été choisi pour sa capacité à représenterle caractère discontinu de la maçonnerie. Une loi d’interface cohésive enmode mixte (I+II) aété mise au point afin de prendre en compte l’endommagement progressif et la dissipationd’énergie associés au comportement quasi-fragile des joints de mortier. Un protocole expérimentalpermettant d’estimer l’ensemble des paramètres cohésifs et frictionnels des jointsde mortier a également été mis au point.Le modèle numérique proposé est confronté à deux essais expérimentaux menés sur desmurs sollicités en cisaillement sous deux conditions aux limites différentes. L’analyse desrésultats obtenusmet en avant l’insuffisance de la loi deMode II proposée à décrire précisémentle comportement en cisaillement dans certains cas. Des voies d’amélioration concernantla modélisation sont donc proposées, comprenant notamment l’étude précise du couplageentre l’endommagement (comportement cohésif) et le comportement frictionnel desjoints sollicités en cisaillement. / Stone masonry is an age-old constructive technique, nevertheless the mechnicalbehavior of this type of construction is still misunderstood. Consequently, standardsfor masonry structural design are very conservative and overestimate design of this kind ofstructures. Moreover, engineers cannot rely on suitable design code to assess masonry buildings.This research project aims to develop a design code suitable for structural masonrydesign to help engineers.Discrete element code LMGC90 was picked for its capacity to take into account masonrydiscontinuities. A mixed mode I+II cohesive interface law is established in order to considerprogressive damage and energy dissipation associated to quasi-brittle behaviour of mortarjoints. An experimental procedure was also carried out to estimate the whole cohesive andfrictional parameters ofmortar joints.The proposed numerical model is confronted to two experimental tests on shear masonrywalls under two different boundary conditions. The results of the analysis shows that thedeveloped model fails at reproducing precisely the shear behaviour especially when the normalstress to the joint strongly increses during the test. Thus we discuss on the Mode II law,and more specifically on the separation of frictional and cohesive behaviours which must beresponsible for the deficient results.

Esta investigación tiene como objetivo evaluar el desempeño geotécnico del suelo arcilloso de alta plasticidad de la urbanización Sudamérica en Talara- Piura, mediante la incorporación de dos materiales reciclados polvo cerámico (PCR) y yeso (YSR). En primer lugar, se optó por clasificar el suelo en estados natural el cual se caracterizó por ser una arcilla de alta plasticidad, para luego realizar los ensayos de contenido de humedad, granulometría y límites de consistencia. En segundo lugar, se analizó la muestra con las dos adiciones incorporadas con porcentajes de 2.5%, 5% y 7.5% de YSR y 5%, 10% y 15% de PCR, con el propósito de analizar cuál fue la influencia de las adiciones en la densidad seca y la resistencia a la compresión no confinada del suelo adicionado. Finalmente, los resultados de laboratorio analizados demostraron que la incorporación de los agentes estabilizadores de YSR y PCR aumentan en 7.5% en la densidad máxima seca y 13.5% en el óptimo contenido de humedad respecto a los valores iniciales del suelo en estado natural. Además, la resistencia a la compresión no confinada incrementó, de un valor promedio, de 6.3 kg/cm2 a 28.8 kg/cm2. Estos resultados muestran que al incorporar las adiciones de PCR y YSR son un método valido de implementación frente a fuerzas de compresión, ya que aumentan la capacidad resistente del suelo. / This research aims to evaluate the geotechnical performance of the highly plastic clay soil of the South American urbanization in Talara-Piura, by incorporating two recycled materials: ceramic powder (PCR) and gypsum (YSR). In the first place, it was decided to classify the soil in natural states which was characterized by being a clay of high plasticity, and then carry out tests for moisture content, grain size and consistency limits. Secondly, the sample was analyzed with the two additions incorporated with percentages of 2.5%, 5% and 7.5% of YSR and 5%, 10% and 15% of PCR, in order to analyze what was the influence of the additions in the dry density and unconfined compressive strength of the added soil. Finally, the analyzed laboratory results showed that the incorporation of the stabilizing agents of YSR and PCR increase by 7.5% in the maximum dry density and 13.5% in the optimal moisture content with respect to the initial values of the soil in the natural state. Furthermore, unconfined compressive strength increased, from an average value, from 6.3 kg / cm2 to 28.8 kg / cm2. These results show that incorporating the additions of PCR and YSR are a valid method of implementation against compression forces, since they increase the resistant capacity of the soil. / Tesis

Cette thèse vise à réaliser des développements théoriques et numériques portant sur le comportement en cyclage thermomécanique de nouveaux alliages de brasure. L’objectif est de proposer une méthodologie de simulation de la fatigue des assemblages électroniques intégrant ce type de brasures. De nombreux modèles semi-empiriques de fatigue existent déjà mais ont montré leurs limites pour une prédiction suffisamment précise de la fiabilité. Il existe donc un besoin d’enrichir les approches existantes par une description des mécanismes de défaillance à l’échelle mésoscopique, en prenant en compte la microstructure fine de l’alliage d’étain. Une formulation décrivant la plasticité cristalline de l’étain et l’endommagement aux joints de grains a donc été développée et intégrée dans un code de calcul pour simuler les mécanismes de déformation dans le joint de brasure. / This thesis aims to carry out theoretical and numerical developments on the thermo-mechanical cyclic behavior of new solder alloys. The objective is to propose a methodology for modeling the fatigue of electronic packages including this type of solders. Several semi-empirical fatigue models already exist, but have shown their limitations for an accurate sufficiently prediction of reliability. Therefore, it requires to enrich the existing approaches by a description of failure mechanisms in the mesoscopic scale, taking into account the fine microstructure of the alloy of tin. A formulation describing the crystal plasticity of tin and the damage of grain boundaries has therefore been developed and integrated in the finite element code for simulating the fracture mechanisms of solder joint.

L’objectif de cette thèse est d’étudier l’évolution de la fissure sous les effets de plasticité et du champ de contrainte non-uniforme à l’aide du modèle de zone cohésive. Dans un premier temps, l’évolution de la fissure au sein du matériau élastoplastique est explorée dans le cadre de l’approche variationnelle. Les solutions sont explicitées dans le cas d’une barre 1D sous traction simple grâce aux conditions de stabilité locale d’énergie au premier ordre et au second ordre. Cette étude nous permet de mettre en lumière l’effet de la plasticité sur le comportementadoucissant du matériau dès que la fissure cohésive apparaît. En effet, la réponse globale de la barre sous déplacement imposé est stable seulement si la longueur de la barre est inférieure à une longueur critique. Cette dernière est démontrée indépendante du module d’écrouissage plastique mais dépend du module Young et de la dérivée seconde de la densité d’énergie de fissure. Les formulations énergétiques peuvent être généralisées pour la structure 3D. Dans ce cas, les critères de plasticité et de cohésif deviennent les courbes dans le plan des contraintes de Mohr. La comparaison des courbes nous permet d’étudier la nucléation de fissure cohésive au sein du domaine plastifié. Dans un deuxième temps, les effets de la non-uniformité du champ de contrainte sur la nucléation de la fissure au sein de la structure élastique sont mis en évidence. On construit la solution analytique en utilisant la technique à deux échelles et l’analyse complexe. L’évolution de la fissure purement cohésive et partiellement non-cohésive est contrôlée par le gradient du champ de contrainte lié à une longueur caractéristique. L’utilisation des différentes lois cohésives dans le problème est explorée. La sensibilité de la solution à la taille du défaut préexistant est également étudiée. Finalement, des résultats analytiques sont validés par les simulations numériques et le modèle de zone cohésive en mode mixte est implémenté dans Code_Aster. / The aims of this work is to study the cracks evolution under plasticity and nonuniform stress field effects by using cohesive zone model. Firstly, basing on the variational approach, the crack evolution in the elastoplastic material is investigated. The solutions for 1D beam under simple tension is expressed explicitly through the first and the second orders stability conditions of energy. This study shows us the plasticity effects on the material softening behavior as soon as crack appears. In fact, the global solution of the beam under described displacement is stable only if the beam length is lower than a characteristic length. This length is independent of plasticity hardening module but depends on Young modulus and on the second derivative of crack energy density. The energy formulations can be generalized for 3D structure. In this case, the plasticity and cohesive criteria become two curves in Mohr’s stresses plane. The comparison between theses curves allows us to consider the crack nucleation in the plastified domain. Secondly, the non-uniform stress field effects on the crack nucleation in the elastic material is highlighted. The analytical solution is established by using two-scales techniqueand complex analysis. The evolution of fully cohesive crack and partially non-cohesive crack is controlled by the stress gradient, which is related to a characteristic length. Different cohesive laws are used in our study. The sensitivity of solution to preexisting imperfection size is also explored. Finally, analytical results are validated by numerical simulations and the cohesive zone model in mixed mode is implemented in Code_Aster.

[pt] Apresentamos um método computacional na GPU que lida com eventos de fragmentação dinâmica, simulados por meio de zona coesiva. Implementamos uma estrutura de dados topológica simples e especializada para malhas com triângulos ou tetraedros, projetada para rodar eficientemente e minimizar ocupação de memória na GPU. Apresentamos um código dinâmico paralelo, adaptativo e distribuído que implementa a formulação de modelo zona coesiva extrínsica (CZM), onde elementos são inseridos adaptativamente, onde e quando necessários. O principal objetivo na implementação deste framework computacional reside na habilidade de adaptar a malha de forma dinâmica e consistente, inserindo elementos coesivos nas facetas fraturadas e inserindo e removendo elementos e nós no caso da malha adaptativa. Apresentamos estratégias para refinar e simplificar a malha para lidar com simulações dinâmicas de malhas adaptativas na GPU. Utilizamos uma versão de escala reduzida do nosso modelo para demonstrar o impacto da variação de operações de ponto flutuante no padrão final de fratura. Uma nova estratégia de duplicar nós conhecidos como ghosts também é apresentado quando distribuindo a simulação em diversas partições de um cluster. Deste modo, resultados das simulações paralelas apresentam um ganho de desempenho ao adotar estratégias como distribuir trabalhos entre threads para o mesmo elemento e lançar vários threads por elemento. Para evitar concorrência ao acessar entidades compartilhadas, aplicamos a coloração de grafo para malhas não-adaptativas e percorrimento nodal no caso adaptativo. Experimentos demonstram que a eficiência da GPU aumenta com o número de nós e elementos da malha. / [en] A GPU-based computational framework is presented to deal with dynamic failure events simulated by means of cohesive zone elements. We employ a novel and simplified topological data structure relative to CPU implementation and specialized for meshes with triangles or tetrahedra, designed to run efficiently and minimize memory requirements on the GPU. We present a parallel, adaptive and distributed explicit dynamics code that implements an extrinsic cohesive zone formulation where the elements are inserted on-the-fly, when needed and where needed. The main challenge for implementing a GPU-based computational framework using an extrinsic cohesive zone formulation resides on being able to dynamically adapt the mesh, in a consistent way, by inserting cohesive elements on fractured facets and inserting or removing bulk elements and nodes in the adaptive mesh modification case. We present a strategy to refine and coarsen the mesh to handle dynamic mesh modification simulations on the GPU. We use a reduced scale version of the experimental specimen in the adaptive fracture simulations to demonstrate the impact of variation in floating point operations on the final fracture pattern. A novel strategy to duplicate ghost nodes when distributing the simulation in different compute nodes containing one GPU each is also presented. Results from parallel simulations show an increase in performance when adopting strategies such as distributing different jobs amongst threads for the same element and launching many threads per element. To avoid concurrency on accessing shared entities, we employ graph coloring for non-adaptive meshes and node traversal for the adaptive case. Experiments show that GPU efficiency increases with the number of nodes and bulk elements.

No description available.

Timber-concrete composite (TCC) structures are becoming more popular in several industrial applications as an efficient method for optimizing the structural performance and the cost of construction as well as lowering the emissions of carbon dioxide. TCC floors are more sustainable than pure concrete floors and more resistant to vibrations and excessive deflections than pure wooden floors. The effectiveness of a TCC floor is dependent on the connection between the materials. The stiffness and strength of the composite element increases by having a rigid connection. An example of a rigid connection is an adhesive-bonded connection, however obtaining a connection without slip is difficult considering there will always be certain amount of slippage in the connection. In this thesis adhesive connections are investigated with two different types of adhesive, one called Sikasil SG-500 and the other Sika PS. The application of the adhesives for the test specimen differ. Since Sika PS is a more fluid glue, a different approach was necessary than for the Sikasil SG-500. Five test specimen were tested of each adhesive by performing double shear push out tests and comparing the results to a numerical model, which was performed in ABAQUS. In the numerical model, the adhesive was created as a cohesive element. Furthermore the properties of the modeled adhesive was based on the experimental results for respective adhesive. The experimental results showed that both adhesives managed the estimated shear force in the serviceability limit state and the ultimate limit state and yet remained in the elastic region. Sikasil SG-500 turned out to be more flexible while Sika PS specimen resulted in higher shear strength. The short creep tests (30 minutes of a constant load) showed that the deformation increased more for Sika PS than for Sikasil SG-500. However both adhesives had large deformations after only 30 minutes. There was also a difference in the average longitudinal shear strength, where it resulted in 1.06 MPa for Sikasil SG-500 and 2.02 MPa for Sika PS. This study indicates that Sika PS is more preferable in TCC structures than Sikasil SG-500.

Transparent trä biokompositer (TW) är en ny attraktiv klass av biokomposit. De är uppbyggda av delignifierat trä som impregnerats med en polymer med matchande brytningsindexet.  TW kan skräddarsys för inom ett brett spektrum av funktionella, optiska och mekaniska egenskaper. Eftersom de är biobaserade ses de dessutom som ett möjligt material som kan ersätta andra, mer miljöpåverkande material, inom olika sektorer, däribland byggnadsindustrin. Till skillnad från de funktionella egenskaperna har det mekaniska beteendet hos dessa biokompositer dock inte undersökts särskilt ingående. Syftet med denna avhandling är därför att utöka den nuvarande kunskapen om det mekaniska beteendet av dessa material genom att använda två olika mekanisk karakterisering metoder av TW och vanligt trä som referensmaterial. TW framställdes genom impregnering av delignifierade björkfaner med PMMA. Den mekaniska karakteriseringen utfördes med hjälp av olika metoder. Elastiska modulen och böjhållfastheten i tvärriktningen studerades med hjälp av fyrpunktsböjningprov. Resultaten visade en förbättring för båda egenskaperna jämfört med vanligt björkträ. Brottet vinkelrätt mot fibern (TR-systemet) undersöktes genom att utföra in situ fyrpunktsböjningstester på prover med en kant-spricka i ett svepelektronmikroskop för att observera hur sprickorna fortplantar sig i den komplexa mikrostrukturen. En anmärkningsvärd förbättring (cirka 175 procent) av brottsstyrkan konstaterades jämfört med vanligt trä. Dessutom användes DIC-teknik (digital image correlation) på fyrpunktsböjningstesterna, med kant-spricka, för att studera spänningsfältet under spricktillväxten, särskilt bildandet av brottprocesszonen (FPZ) runt sprickspetsen. Därefter föreslogs en ekvation som beskriver kohesionslagen för båda materialen baserat på experimentella observationer som i slutändan kan användas för sprickmekaniska simuleringar. Slutligen visades kort hur man kan använda de uppmätta mekaniska egenskaperna hos den nya TW för materialval för tekniska tillämpningar. / Transparent wood (TW) biocomposites are a new attractive class of materials. They are based on a delignified wood template impregnated by a refractive index-matching polymer.  TWs can be tailored in order to show a wide range of functional, optical, and mechanical properties. Moreover, being biobased, they are seen as a possible key material to replace more environmentally impactful materials in various sectors including the construction industry. However, unlike the functional properties, the mechanical behaviour of this class of materials has been poorly investigated. Therefore, in this thesis, the aim was to extend the current knowledge about the mechanical response of these materials by using a two-step mechanical characterization on TW and native wood as reference material. The analysed TW biocomposite was prepared by impregnation of delignified birch veneers by PMMA. The mechanical characterization was carried out using different techniques. The Young’s modulus and the flexural strength along the transverse direction were studied by four-point bending tests. The results showed an improvement for both properties compared to native birch wood. The fracture perpendicular to the grain (TR system) was investigated by performing in situ single-edge-notched four-point bending tests onto a scanning electron microscope to observe how the cracks propagate in this complex microstructure. A remarkable improvement (about 175 percent) in fracture toughness was found compared to the native wood. Furthermore, the in situ single-edge-notched four-point bending test was also applied, together with the digital image correlation (DIC) technique, to study the strain field during the crack growth, specifically the formation of the fracture process zone (FPZ) around the crack tip. Then, an equation describing the cohesive law was proposed for both materials based on experimental observations that can be ultimately used for fracture mechanics simulations. Finally, it was briefly shown how to make use of the measured mechanical properties of the novel TW for material selection for engineering applications.