Дисертації з теми "Micropolar Cohesive Damage Model"
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Searcy, Chad Randall. "A multiscale model for predicting damage evolution in heterogeneous viscoelastic media." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1251.
Повний текст джерелаLi, Xiaole. "An extended cohesive damage model for simulating crack propagation in fibre reinforced composies." Thesis, University of Portsmouth, 2016. https://researchportal.port.ac.uk/portal/en/theses/an-extended-cohesive-damage-model-for-simulating-crack-propagation-in-fibre-reinforced-composies(c8a15f4e-826e-444a-9c8a-758b75f8c742).html.
Повний текст джерелаThomas, Michael Andrew. "Framework for Cohesive Zone Model Based Multiscale Damage Evolution in a Fatigue Environment." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1308257790.
Повний текст джерелаMay, Michael. "A new model for initiation of damage in composites under fatigue loading for cohesive elements." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521074.
Повний текст джерелаLi, Bo. "Applications of Cohesive Zone Models in Dynamic Failure Analysis." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1459953377.
Повний текст джерелаJosefsson, Axel, and Johan Wedin. "Convergence properties of a continuum damage mechanics model for fatigue of adhesive joints." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-10188.
Повний текст джерелаBahadursha, Venkata Rama Lakshmi Preeethi. "Tearing of Styrene Butadiene Rubber using Finite Element Analysis." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431029910.
Повний текст джерелаCuvilliez, Sam. "Passage d’un modèle d’endommagement continu régularisé à un modèle de fissuration cohésive dans le cadre de la rupture quasi-fragile." Thesis, Paris, ENMP, 2012. http://www.theses.fr/2012ENMP0064/document.
Повний текст джерелаThe present work deals with the study and the improvement of regularized (non local) damage models. It aims to study the transition from a continuous damage field distributed on a structure to a discontinuous macroscopic failure model.First, an analytical one-dimensional study is carried out (on a bar submitted to tensile loading) in order to identify a set of interface laws that enable to switch from an inhomogeneous solution obtained with a continuous gradient damage model to a cohesive zone model. This continuous / discontinuous transition is constructed so that the energetic equivalence between both models remains ensured whatever the damage level reached when switching.This strategy is then extended to the bi-dimensional (and tri-dimensional) case of rectilinear (and plane) crack propagation under mode I loading conditions, in a finite element framework. An explicit approach based on a critical damage criterion that allows coupling both continuous and discontinuous approaches is then proposed. Finally, results of several simulations led with this coupled approach are presented
Swindeman, Michael James. "A Regularized Extended Finite Element Method for Modeling the Coupled Cracking and Delamination of Composite Materials." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1324605778.
Повний текст джерелаCabello, Ulloa Mario Javier. "Desarrollo de modelos para el cálculo de uniones estructurales con adhesivos flexibles." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/403837.
Повний текст джерелаLes unions adhesives són especialment interessants en aplicacions estructurals i el seu ús ha augmentat notablement en la industria moderna. No obstant, el disseny d’una unió adhesiva segueix essent actualment un repte per als enginyers, doncs no es disposa de models eficaços per a predir el seu comportament. Particularment, la utilització d’adhesius flexibles s’està estenent cada vegada méss degut als avantatges que aquests ofereixen, i actualment s’estan duent a terme nombrosos esforços per obtenir models analítics méss eficaços que permetin poder analitzar-ne el seu comportament. Els models existents, desenvolupats per adhesius compressibles i rígids no son capaços de predir amb precisió el comportament d’unions amb adhesius flexibles, que presenten un mòdul elàstic baix, incompressibilitat i grans deformacions fins a la seva ruptura. Els models analítics més avançats incorporen l’efecte de l’elasticitat de l’adhesiu en la seva formulació com una distribució constant, i com que no tenen en compte aspectes com l’efecte de les tensions sobre la rigidesa de l’adhesiu, la influència del dany i les grans deformacions a la capa de l’adhesiu no són suficientment precisos en la modelització del comportament de la unió.
Las uniones adhesivas son de especial interés en aplicaciones estructurales y su uso ha aumentado notablemente en la industria moderna. Sin embargo, el diseño de uniones adhesivas sigue siendo a día de hoy un reto para los ingenieros que carecen de modelos eficaces para la predicción de su comportamiento. En particular, el uso de adhesivos flexibles se ha convertido en una tendencia en la industria debido a las ventajas que estos ofrecen y se están dedicando numerosos esfuerzos para lograr modelos analíticos más eficaces. Los modelos existentes, desarrollados para adhesivos compresibles rígidos, no son capaces de predecir con precisión el comportamiento de uniones con adhesivos flexibles que presentan bajo módulo elástico, incompresibilidad y grandes deformaciones hasta la rotura. Los modelos analíticos más avanzados incorporan el efecto de la elasticidad del adhesivo en su formulación como una distribución constante y aún carecen de suficiente precisión debido a que no toman en cuenta efectos como la influencia del estado tensional sobre la rigidez, la influencia del daño y las grandes deformaciones presentes en la capa de adhesivo.
Lotura itsasgarriak interes handiko loturak dira aplikazio estrukturaletarako eta bereerabilera nabarmenki handitzen joan da industria mailan. Hala ere, gaur egun loturaitsasgarrien diseinuak erronka izaten jarraitzen du, ingeniariek horien portaera ezagutzekoeredu egokirik ez daukatelako. Konkretuki, itsasgarri malguen erabilera joera bilakatuda industria mailan, eskaintzen dituzten abantailengatik, eta hori dela eta ahalegin handiakegiten ari dira eredu analitiko eraginkorragoak lortzeko. Erabilgarri dauden ereduak,itsasgarri zurrun konprimigarrietarako garatuak zainik, ez dira gai modulu elastiko baxua,konprimitzeko ezintasuna eta haustura arteko deformazio handiak jasaten dituztenitsasgarri malguen jarrera iragartzeko. Eredu analitiko garatuenek itsasgarriaren malgutasunarenefektua banaketa konstante bezala moduan agertzen dute, eta oraindik zehaztasunfalta dute, zurruntasunaren tentsio egoeraren efektuak, kaltearen eragina eta itsasgarriangertatzen diren deformazio handiak kontuan hartzen ez dituztelako.
Wolf, Johannes. "Traitement numérique de la fissuration dans les matériaux structuraux ductiles sous l’effet de sollicitations sévères." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0040/document.
Повний текст джерелаThe present work aims at numerically predicting the current residual strengthof large engineering structures made of ductile metals regarding accidental events,e.g. ships collision or bird strike in aviation, which may potentially lead to failure.With this aim in view, the challenge consists in reproducing within a unified finiteelement (FE)-based methodology the successive steps of micro-voiding-induceddamage, strain localization and crack propagation, if any.A key ingredient for a predictive ductile fracture model is the proper numericaltreatment of the critical transition phase of damage-induced strain localizationinside a narrow band. For this purpose, three different viewpoints in terms ofdisplacement field across the localization band are proposed involving a strong,weak and (non-linearly) regularized discontinuity, respectively.A consistent variational framework is elaborated for each of the three methods,whereby the enriched kinematics is embedded into the FE formulation using theeXtended FEM. Then, within a comparative procedure, the performance of thesemethods is assessed regarding their ability of modeling the transition phase betweendiffuse damage (continuum mechanics framework) and crack propagation (fracturemechanics framework), always in the context of ductile materials.According to the aforementioned analyses, the combination of the strong discontinuitycohesive model and the X-FEM appears to be the most promising of thethree studied approaches to bring together physics and numerics. The developmentof such a model is discussed in detail. Finally, two supplementary criteria aredefined: the first one for the passage from diffuse damage to the cohesive bandmodel and the second one for the passage from the cohesive band model to thecrack
Llobet, Vallejo Jordi. "A constitutive model for fatigue and residual strength predictions of composite laminates." Doctoral thesis, Universitat de Girona, 2020. http://hdl.handle.net/10803/670692.
Повний текст джерелаAquesta tesi investiga la resposta a fatiga de laminats compòsits fabricats amb fibra de carboni. L'estudi de la fatiga en materials compòsits és un tema de gran complexitat tant des d'un punt de vista experimental com de modelització computacional. En aquest context, s'ha dissenyat una àmplia campanya experimental per investigar els mecanismes de dany que apareixen quan el material es sotmet a càrregues cícliques o a fatiga. Al mateix temps, s'ha desenvolupat un model constitutiu per anticipar la resposta estructural i la resistència final del material. Aquest model s'ha implementat dins d'un codi d'elements finits per tal d'analitzar estructures aeronàtutiques en diferent condicions de càrrega. L'objectiu final d'aquest models computacionals és la de reduir el nombre d'assajos experimentals i el temps que es necessita per certificar estructures aeronàutiques
Roth, Stephan. "Entwicklung und Implementierung zyklischer Kohäsivzonenmodelle zur Simulation von Werkstoffermüdung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-209735.
Повний текст джерелаCyclic cohesive zone models describe irreversible separation behaviour and damage accumulation under cyclic loading. In the present thesis, the formulation of cyclic cohesive zone models is systemised and their potential to simulate fatigue processes is analysed. The relation between traction and separation is described based on established thermodynamical concepts of damage mechanics. Cyclic damage accumulation is controlled by a damage evolution equation taking into account a state-dependent endurance limit. The cohesive zone model is applied successfully to the simulation of material fatigue. Fatigue crack growth rate curves, which were obtained numerically by means of the finite element method, reproduce the experimentally observed behaviour in all stages. The influences of the particular parameters of the model are determined by parametric studies. In addition, simulations of uniaxial fatigue tests using the cyclic cohesive zone model are presented. Furthermore, the size effect on the fatigue behaviour is investigated. The relation between the local states within the cohesive zone and the predicted global failure modes is explained. These findings form the foundation for a concept of parameter identification which bases on the evaluation of Wöhler-curves and fatigue crack growth rate curves
Lé, Benoît. "Contribution à la simulation numérique des structures en béton armé : utilisation de fonctions de niveau pour la modélisation de la fissuration et des renforts." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0003/document.
Повний текст джерелаPrediction of cracking is a key point for the analysis ofreinforced concrete structures, which requires the use of Modeling and numerical simulation. The analysis of reinforced concrete structures using the finite element method raises two issues: on one hand, few models areable to deal with the initiation, the propagation and the opening of cracks, on the other hand the diameter of thereinforcements which is usually small compared to the dimensions of the structures necessitates very fine meshes. Some solutions to these two problematics areproposed, based on the use of level set functions.Damage and cracking of concrete are modeled using theThick Level Set (TLS) approach. This method,developped as a mean to regularize local damagemodels, uses a level set to introduce a characteristic length. It makes the location of the cracks easy, whichallows to enrich the displacement field with the eXtendedFinite Element Method (X-FEM) in order to model the macro-cracks opening. Concerning the modeling of thereinforcements, a new multidimensionnal approach isproposed. A volumic representation of the reinforcements with the X-FEM method is used in the zones of interest to get accurate results while simplifying the meshing process, whereas a lineic representation isused elsewhere to decrease the number of degrees of freedom. The developed transition method insures the consistency of the results
Susila, Gede Adi. "Experimental and numerical studies of masonry wall panels and timber frames of low-rise structures under seismic loadings in Indonesia." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-numerical-studies-of-masonry-wall-panels-and-timber-frames-of-lowrise-structures-under-seismic-loadings-in-indonesia(3ceb094b-4e6e-432a-b3de-3d4c306b0551).html.
Повний текст джерелаDeepu, S. P. "Non-Local Continuum Models for Damage in Solids and Delamination of Composites." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4206.
Повний текст джерела"Numerical Study on Cohesive Zone Elements for Static and Time Dependent Damage and its Application in Pipeline Failure Analysis." Master's thesis, 2016. http://hdl.handle.net/2286/R.I.40317.
Повний текст джерелаDissertation/Thesis
Masters Thesis Mechanical Engineering 2016
Τσαλούφη, Μαρίνα. "Αριθμητική προσομοίωση της μηχανικής συμπεριφοράς συνδέσεων με κόλλα πολύστρωτων πλακών". Thesis, 2012. http://hdl.handle.net/10889/5873.
Повний текст джерелаThis work is based on the development of three-dimensional numerical model based on the finite element method to simulate the mechanical behavior of adhesive bonded joints in composite materials. The model was developed in finite element procedures under the framework of the commercial software ANSYS. To simulate the behavior of the adhesive used two approaches: the cohesive zone modeling (CZM) and the continuum damage modeling (CDM). These two approaches are compared both in terms of reliability, which is determined by comparison with experimental results, and applicability, which is determined by the parameters required and the computational time. The comparison between the two methodologies was the basis of their application to simulate the mechanical behavior under mode-I fracture behavior of adhesively bonded joints between two CFRP plates. This problem was chosen because there were experimental results to compare in the laboratory. The sandwich plates are modeled using the stromal element of ANSYS SOLID185. This item each layer separately modeled as orthotropic material. The adhesive is modeled using the interface element of ANSYS INTER205. For the purpose of modeling the failure of continuous medium developed macro routine using the programming language code ANSYS. The numerical results showed that both methodologies simulate sufficient precision the curve force-displacement of the connection. About applicability of the two methods, the comparison showed that the process of cohesive zone modeling outweighs the process of continuum damage modeling because it requires less number of parameters, but falls to the computational time. Both methods are suitable for use in numerical design of adhesively bonded joints.
Roth, Stephan. "Entwicklung und Implementierung zyklischer Kohäsivzonenmodelle zur Simulation von Werkstoffermüdung." Doctoral thesis, 2015. https://tubaf.qucosa.de/id/qucosa%3A23074.
Повний текст джерелаCyclic cohesive zone models describe irreversible separation behaviour and damage accumulation under cyclic loading. In the present thesis, the formulation of cyclic cohesive zone models is systemised and their potential to simulate fatigue processes is analysed. The relation between traction and separation is described based on established thermodynamical concepts of damage mechanics. Cyclic damage accumulation is controlled by a damage evolution equation taking into account a state-dependent endurance limit. The cohesive zone model is applied successfully to the simulation of material fatigue. Fatigue crack growth rate curves, which were obtained numerically by means of the finite element method, reproduce the experimentally observed behaviour in all stages. The influences of the particular parameters of the model are determined by parametric studies. In addition, simulations of uniaxial fatigue tests using the cyclic cohesive zone model are presented. Furthermore, the size effect on the fatigue behaviour is investigated. The relation between the local states within the cohesive zone and the predicted global failure modes is explained. These findings form the foundation for a concept of parameter identification which bases on the evaluation of Wöhler-curves and fatigue crack growth rate curves.
Goldmann, Joseph. "Schädigungsprognose mittels Homogenisierung und mikromechanischer Materialcharakterisierung." Doctoral thesis, 2017. https://tud.qucosa.de/id/qucosa%3A31075.
Повний текст джерелаThe thesis at hand is concerned with the question if numerical homogenization schemes can be of use in deriving effective material properties of composite materials after the onset of strain localization due to strain softening. In this case, the usefulness of computational homogenization methods has been questioned in the literature. Hence, all the subtasks to be solved in order to provide a successful homogenization scheme are investigated herein. The first of those tasks is the characterization of the constituents, which form the composite. To allow for an experimentally based characterization an exemplary composite has to be chosen, which herein is a glass fiber reinforced epoxy. Hence the constituents to be characterized are the epoxy and the glass fibers. Furthermore, special attention is paid to the characterization of the interface between both materials. In case of the glass fibers, the measured strength values do not comply with the weakest link hypothesis. Numerous generalizations of the Weibull distribution are investigated, to account for interfering effects. Finally, distributions are derived, that incorporate the possibility of failure inside the clamped fiber length. Application of such a distribution may represent the measured data quite well. Additionally, it renders the cumbersome process of sorting out and repeating those tests unnecessary, where the fiber fails inside the clamps. Identifying the interface parameters of the proposed cohesive zone model relies on data from pullout and single fiber fragmentation tests. The agreement of both experiments in terms of interface strength and energy release rate is very good, where the parameters are identified by means of an evaluation based on finite element models. Also, the agreement achieved is much better than the one typically reached by an evaluation based on simplified analytical models. Beside the derivation of parameterized material models as an input, the homogenization scheme itself needs to be generalized after the onset of strain localization. In an assessment of the current state of the literature, prior to the generation of representative volume elements and the averaging operator, the boundary conditions (BC) are identified as a significant issue of such a homogenization scheme. Hence, periodic BC, linear displacement BC and minimal kinematic BC as well as two adaptive BC, namely percolation path aligned BC and generalized periodic BC are investigated. Furthermore, a third type of adaptive BC is proposed, which is called tesselation BC. Firstly, the three adaptive BC are proven to fulfill the Hill-Mandel condition. Secondly, by modifying the Hough transformation an unbiased criterion to determine the direction of the localization zone is given, which is necessary for adaptive BC. Thirdly, the properties of all the BC are demonstrated in several examples. These show that tesselation BC are the only type, that allows for arbitrary directions of localization zones, yet is totally unsusceptible to spurious localization zones in corners of representative volume elements. Altogether, fundamental objections, that have been raised in the literature against the application of homogenization in situations with strain localization, are rebutted in this thesis. Hence, the basic feasibility of homogenization schemes even in case of strain softening material behavior is shown.