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Littérature scientifique sur le sujet « Crystal Plasticity Finite Element Modelling »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 17 février 2022

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Articles de revues sur le sujet "Crystal Plasticity Finite Element Modelling"

CHEN, Y. P., W. B. LEE, S. TO et H. WANG. « FINITE ELEMENT MODELLING OF MICRO-CUTTING PROCESSES FROM CRYSTAL PLASTICITY ». International Journal of Modern Physics B 22, n^o 31n32 (30 décembre 2008) : 5943–48. http://dx.doi.org/10.1142/s0217979208051418.

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In ultra-precision machining (UPM), the depth of cut is within an extremely small fraction of the average grain size of the substrate materials to be cut. Polycrystalline materials commonly treated as homogeneous in conventional machining have to be considered as heterogeneous. The cutting force, one of the dominant factors influencing the integrity of the machined surface in UPM, is observed to strongly depend on the grain orientations. To accurately capture the intrinsic features and gain insight into the mechanisms of UPM of single crystals, the crystal plasticity constitutive model has been incorporated into the commercial FE software Marc by coding the user material subroutine Hypela2 available within it. The enhanced capability of the FE software will be adopted to simulate factors influencing the micro-cutting processes, such as grain orientation variation, the tool edge radius and the rake angle. The simulation results will provide useful information for the optimization of critical processing parameters and enhancement of quality of machined products.

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Brocks, Wolfgang, Alfred Cornec et Dirk Steglich. « Two-Scale Finite Element Modelling of Microstructures ». Advanced Materials Research 59 (décembre 2008) : 3–17. http://dx.doi.org/10.4028/www.scientific.net/amr.59.3.

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Modelling the constitutive behaviour of metallic materials based on their microstructural features and the micromechanical mechanisms in the framework of continuum mechanics is addressed. Deformation at the lengthscale of grains is described by crystal plasticity. The macroscopic behaviour is obtained either by a homogenisation process yielding phenomenological equations or by a submodel technique. The modelling processes for two light-weight materials, namely magnesium and titanium aluminides are presented.

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Li, Hei Jie, Jing Tao Han, Zheng Yi Jiang, Hua Chun Pi, Dong Bin Wei et A. Kiet Tieu. « Crystal Plasticity Finite Element Modelling of BCC Deformation Texture in Cold Rolling ». Advanced Materials Research 32 (février 2008) : 251–54. http://dx.doi.org/10.4028/www.scientific.net/amr.32.251.

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Taylor-type and finite element polycrstal models have been embedded into the commercial finite element code ABAQUS to carry out the crystal plasticity finite element modelling of BCC deformation texture based on rate dependent crystal constitutive equations. Initial orientations measured by EBSD were directly used in crystal plasticity finite element model to simulate the development of rolling texture of IF steel under various reductions. The calculated results are in good agreement with the experimental values. The predicted and measured textures tend to sharper with an increase of reduction, and the texture obtained from the Taylor-type model is much stronger than that by finite element model. The rolling textures calculated with 48 {110}<110>, {112}<111> and {123}<111> slip systems are close to the EBSD results.

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Bate, Peter. « Modelling deformation microstructure with the crystal plasticity finite–element method ». Philosophical Transactions of the Royal Society of London. Series A : Mathematical, Physical and Engineering Sciences 357, n^o 1756 (15 juin 1999) : 1589–601. http://dx.doi.org/10.1098/rsta.1999.0391.

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Liu, Mao, Cheng Lu et Anh Kiet Tieu. « Crystal plasticity finite element method modelling of indentation size effect ». International Journal of Solids and Structures 54 (février 2015) : 42–49. http://dx.doi.org/10.1016/j.ijsolstr.2014.11.008.

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Grilli, Nicolò, Alan C. F. Cocks et Edmund Tarleton. « Crystal plasticity finite element modelling of coarse-grained α-uranium ». Computational Materials Science 171 (janvier 2020) : 109276. http://dx.doi.org/10.1016/j.commatsci.2019.109276.

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Sajjad, Hafiz Muhammad, Stefanie Hanke, Sedat Güler, Hamad ul Hassan, Alfons Fischer et Alexander Hartmaier. « Modelling Cyclic Behaviour of Martensitic Steel with J2 Plasticity and Crystal Plasticity ». Materials 12, n^o 11 (31 mai 2019) : 1767. http://dx.doi.org/10.3390/ma12111767.

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In order to capture the stress-strain response of metallic materials under cyclic loading, it is necessary to consider the cyclic hardening behaviour in the constitutive model. Among different cyclic hardening approaches available in the literature, the Chaboche model proves to be very efficient and convenient to model the kinematic hardening and ratcheting behaviour of materials observed during cyclic loading. The purpose of this study is to determine the material parameters of the Chaboche kinematic hardening material model by using isotropic J2 plasticity and micromechanical crystal plasticity (CP) models as constitutive rules in finite element modelling. As model material, we chose a martensitic steel with a very fine microstructure. Thus, it is possible to compare the quality of description between the simpler J2 plasticity and more complex micromechanical material models. The quality of the results is rated based on the quantitative comparison between experimental and numerical stress-strain hysteresis curves for a rather wide range of loading amplitudes. It is seen that the ratcheting effect is captured well by both approaches. Furthermore, the results show that concerning macroscopic properties, J2 plasticity and CP are equally suited to describe cyclic plasticity. However, J2 plasticity is computationally less expensive whereas CP finite element analysis provides insight into local stresses and plastic strains on the microstructural length scale. With this study, we show that a consistent material description on the microstructural and the macroscopic scale is possible, which will enable future scale-bridging applications, by combining both constitutive rules within one single finite element model.

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Hartig, Ch, et H. Mecking. « Crystal Plastic Finite Element Simulation of Fe-Cu Polycrystals ». Materials Science Forum 495-497 (septembre 2005) : 1621–26. http://dx.doi.org/10.4028/www.scientific.net/msf.495-497.1621.

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The plastic and elastic deformation of PM two-phase Iron-Copper polycrystals was studied experimentally and modelled by a FEM model calculation, taking into account anisotropic elasticity and crystal plasticity. Following quantities were experimentally measured and calculated by a FEM model calculation: A local strain distribution and rolling textures. For a judgement of model predictions the orientation densities of the bcc a-fibres of Iron and of the fcc b-fibres of Copper were considered. Good predictions of the texture evolution were found in cases only, where local micromechanical interactions are not too much influenced by the heterogeneity of the microstructure. The implications of these results for the development and use of FEM schemes for modelling heterogeneous polycrystal plasticity are discussed.

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Qin, Xiaoyu, Guomin Han, Shengxu Xia, Weijie Liu et De-Ye Lin. « Crystal Plasticity Finite Element Method for Cyclic Behavior of Single Crystal Nickel-Based Superalloy ». Journal of Multiscale Modelling 12, n^o 01 (18 février 2021) : 2150002. http://dx.doi.org/10.1142/s1756973721500025.

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This paper reports the modeling and simulation of cyclic behavior of single crystal nickel-based superalloy by using the crystal plasticity finite element method. Material constitutive model based on the crystal plasticity theory is developed and is implemented in a parallel way as user subroutine modules embedded in the commercial Abaqus[Formula: see text] software. For simplicity in calibration and without loss of generality, the crystal plasticity constitutive relationship used in this work takes the form that only contains a few parameters. The parameters are optimized by using the Powell algorithm. We employ the calibrated constitutive model with the finite element solver on a cuboid and a blade to simulate cyclic and anisotropic properties of single crystal superalloy. Results show that the predicted stress–strain curves are in good agreement with the experimental measurements, and anisotropic results are presented in both elastic and plastic regions.

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Wei, Pei Tang, Cheng Lu, Kiet Tieu, Guan Yu Deng et Jie Zhang. « Modelling of Texture Evolution in High Pressure Torsion by Crystal Plasticity Finite Element Method ». Applied Mechanics and Materials 764-765 (mai 2015) : 56–60. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.56.

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In this study, texture evolution during high pressure torsion (HPT) of aluminum single crystal is predicted by the crystal plasticity finite element method (CPFEM) model integrating the crystal plasticity constitutive theory with Bassani & Wu hardening model. It has been found by the simulation that, during the HPT process, the lattice rotates mainly around the radial direction of the sample. With increasing HPT deformation, the initial cube orientation rotates progressively to the rotated cube orientation, and then to the C component of ideal torsion texture which could be remained over a wide strain range. Further HPT deformation leads to the orientation towards to the ideal texture component.

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Thèses sur le sujet "Crystal Plasticity Finite Element Modelling"

Zahedi, S. Abolfazl. « Crystal-plasticity modelling of machining ». Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14588.

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A machining process is one of the most common techniques used to remove material in order to create a final product. Most studies on mechanisms of cutting are performed under the assumption that the studied material is isotropic, homogeneous and continuous. One important feature of material- its anisotropyis linked to its crystallographic nature, which is usually ignored in machining studies. A crystallographic orientation of a workpiece material exerts a great influence on the chip-formation mechanism. Thus, there is a need for developing fundamental understanding of material's behaviour and material removal processes. While the effect of crystallographic orientation on cutting-force variation is extensively reported in the literature, the development of the single crystal machining models is somewhat limited.

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Xu, Yilun. « On the development of a multi-scale modelling framework to study plasticity and damage through the coupling of finite element crystal plasticity and discrete dislocation plasticity ». Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/52630.

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The microstructure of polycrystalline materials crucially determines their mechanical performance in engineering applications. A multi-scale modelling approach is capable of representing the microstructure and thus capturing the material performance for various resolution requirement at different scales. Besides, the application of multi-scale modelling effectively reduces expense and improves efficiency of computations without loss of accuracy at sensitive zones. A method of concurrent coupling of planar discrete dislocation plasticity (DDP) and a crystal plasticity finite element (CPFE) method was devised for simulating plastic deformation in large polycrystals with discrete dislocation resolution in a single grain or cluster of grains for computational efficiency; computation time using the coupling method can be reduced by an order of magnitude compared to DDP. The method is based on an iterative scheme initiated by a sub-model calculation, which ensures displacement and traction compatibility at all nodes at the interface between the DDP and CPFE domains. The proposed coupling approach is demonstrated using two plane strain problems: (i) uniaxial tension of a bi-crystal film and (ii) indentation of a thin film on a substrate. The latter demonstrated that the rigid substrate assumption used in earlier discrete dislocation plasticity studies is inadequate for indentation depths that are large compared to the film thickness, i.e. the effect of the polycrystalline plastic substrate modelled using CPFE becomes important. The coupling method can be used to study a wider range of indentation depths than previously possible using DDP alone, without sacrificing the indentation size effect regime captured by DDP. A comprehensive indentation pressure formula has been developed by applying the proposed multi-scale modelling approach on a polycrystalline coating system. Planar nano-sliding and fretting calculations have been performed on thin films modelling by CPFE and DDP at different scales. Results of CPFE simulations provide an understanding of the role of microstructure on the plasticity and crack initiation during a contact problem. Beside, a new DDP computational framework has been proposed for a nano-fretting problem which is able to capture the contact size effect, simulate the dislocation evolution and predict the surface profile variation of thin films. Calculations of DDP simulations potentially provide CPFE simulations with fatigue parameters that is of more physical significance. The method is general and can be applied to any problem where finer resolution of dislocation mediated plasticity is required to study the mechanical response of polycrystalline materials, e.g. to capture size effects locally within a larger elastic/plastic boundary value problem. Also, the model described here will provide further opportunities for directly coupled, three-tiered multi-scale models compromising an overall macroscopic continua having embedded crystal plasticity and discrete dislocation plasticity models, respectively, as the length scale decreases in the area of interest. Finally, the methodology of the proposed coupling method will shed light on archiving a general compatibility of sub-regions and thus benefit other researchers who are working on coupling methods among other scales.

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Dwyer, Liam Paul. « Steps toward a through process microstructural model for the production of aluminium sheet ». Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/steps-toward-a-through-process-microstructural-model-for-the-production-of-aluminium-sheet(cac0d9a4-0bc5-47e1-ac15-689d02c7c1d4).html.

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Aluminium sheet production is a multi-stage process in which altering processing conditions can drastically alter the size and type of second phase particles found in the final product. The properties of these second phase particles also affects deformation and annealing processes, meaning that any attempt to create a through process model would require the ability to predict both how the particles would develop in the material, and how these particles then affect the alloy moving forward. This project first focuses on gaining insight into how the particles in a model aluminium alloy change during homogenisation heat treatment and hot rolling. This has been accomplished by utilising serial block face scanning electron microscopy (SBF-SEM), a technique which allows the capture of 3D data sets at sub micron resolutions. This has allowed the populations of primary (constituent) and secondary (dispersoid) particles to be analysed at different stages of sheet production, and thus allowing the effects of homogenisation and hot rolling on particle populations to be quantified. To discover how the particles would go on to affect further processing, digital image correlation has been used to examine the localised strain in the alloy near to a selection of particle configurations. This highlighted the heterogeneity in slip behaviour within the alloy and illustrated that plumes of rotation develop near to non deformable regions. Rotation plumes have previously been modelled using a crystal plasticity model, and so further work is also presented expanding upon this model to simulate a variety of particle configurations. This has shown that in the case of single particles, local deformation is dependent on both the aspect ratio of the particle and how it is aligned to the active slip system. With the incorporation of a second particle, the interparticle spacing must also be considered.

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Karamched, Phani Shashanka. « Deformation studies near hard particles in a superalloy ». Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:e740592d-8d82-4c12-9bfe-99901d132b60.

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Superalloys have performed well as blade and disc materials in turbine engines due to their exceptional elevated temperature strength, high resistance to creep, oxidation and corrosion as well as good fracture toughness. This study explores the use of a relatively new technique of strain measurement, high resolution electron backscatter diffraction (HR-EBSD) to measure local deformation fields. The heart of the HR-EBSD technique lies in comparing regions in EBSD patterns from a strained region of a sample to those in a pattern from an unstrained region. This method was applied to study the elastic strain fields and geometrically necessary dislocation density (GND density) distribution near hard carbide particles in a nickel-based superalloy MAR-M-002. Significant thermal strains were initially induced by thermal treatment, which included a final cooling from the ageing temperature of 870°C. Elastic strains were consistent with a compressive radial strain and tensile hoop strain that was expected as the matrix contracts around the carbide. The mismatch in thermal expansion coefficient of the carbide particles compared to that of the matrix was sufficient to have induced localized plastic deformation in the matrix leading to a GND density of 3 x 10¹³ m^–2 in regions around the carbide. These measured elastic strain and GND densities have been used to help develop a crystal plasticity finite element model in another research group and some comparisons under thermal loading have also been examined. Three-point bending was then used to impose strain levels within the range ±12% across the height of a bend bar sample. GND measurements were then made at both carbide-containing and carbide-free regions at different heights across the bar. The average GND density increases with the magnitude of the imposed strain (both in tension and compression), and is markedly higher near the carbide particles. The higher GND densities near the carbides (order of 10¹⁴ per m²) are generated by the large strain gradients produced around the plastically rigid inclusion during monotonic mechanical deformation with some minor contribution from the pre-existing residual deformation from thermal loading. A method was developed of combining the local EBSD measurements with FE modelling to set the average residual strains within the mapped region even when a good strain free reference point was unavailable. Cyclic loading was then performed under four point loading to impose strain levels of about ±8% across the height of bend bar samples. Similar measurements as in the case of monotonic deformation were made at several interruptions to fatigue loading. Observations from the cyclic loading such as slip features, carbide cracking, GND density accumulation have been explored around carbide particles, at regions away from them and near a grain boundary.

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Xie, Mengyin. « X-ray and neutron diffraction analysis and fem modelling of stress and texture evolution in cubic polycrystals ». Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c5f8b36c-4728-4c17-8e2e-82b926200019.

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The thesis reports improvements in the characterization techniques for stress and texture in crystalline materials by x-ray and neutron powder diffraction. Furthermore, advances are made in texture evolution modelling and validation against experimental observations. In the beginning, the fundamental assumption of diffraction strain analysis is numerically examined and verified, namely, that the lattice parameter value determined from fitting the diffraction pattern is equal to the average lattice parameter within the gauge volume. Next, the task of shear strain determination from powder diffraction measurements is addressed. A method is developed and implemented for the complete 2D strain tensor determination from the multi-directional energy-dispersive x-ray diffraction patterns. The method not only offers a way to evaluate the shear strain, but also provides a better overall strain averaging approach. Rotation and translation of sample and/or detectors in powder diffraction mode can effectively increase the pole figure coverage and thus the accuracy of texture determination. However, the movements also introduce uncertainties and aberrations into data analysis due to the changes in the diffraction volume and transmitted intensity. In order to overcome these problems, accurate single exposure texture characterization techniques are proposed based on several different powder diffraction setups. Numerical analyses are carried out to prove that any simple texture in cubic polycrystals can be effectively determined using single exposure Debye-Scherrer diffraction pattern analysis. Several experiments are reported on collecting Debye-Scherrer diffraction patterns, multi-directional energy-dispersive x-ray diffraction patterns and multi-directional TOF neutron setup. Efficient data processing procedures of the diffraction patterns for ODF determination are presented. Crystal plasticity finite element models are developed to model the texture evolution in polycrystalline engineering samples during manufacturing. In the present thesis, quantitative measures extracted from orientation distribution function are employed to make precise comparison between the model and experiment. Unlike the simple uni-axial compression and tension considered in the literature, in the present thesis the complex texture evolution during linear friction welding is modelled as a sequence of different shear deformations.

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Furstoss, Jean. « Approche numérique de l'évolution microstructurale des péridotites ». Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4066.

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Cette thèse a pour but de simuler les évolutions microstructurales des roches du manteau supérieur dans des conditions thermomécaniques représentatives de la lithosphère terrestre. En effet, c’est le comportement mécanique de ces roches qui contrôle, au premier ordre la rhéologie de la lithosphère et donc des plaques tectoniques.Les outils utilisés et développés dans ce travail sont basés sur le formalisme level-set (LS) permettant une description implicite de la microstructure et la modélisation de la migration de joint de grains à l’échelle du polycristal. Les évolutions microstructurales sont simulées dans un cadre élément fini (EF) robuste et efficace permettant un couplage avec des calculs de plasticité cristalline décrivant le comportement mécanique de la roche. Une première grande partie de cette thèse est consacrée à la croissance de grain en absence de déformation dans les péridotites. Il est montré, dans un premier temps que la cinétique de croissance d’un agrégat d’olivine (minéral principal des péridotites) n’est pas en accord avec les contraintes naturelles sur la cinétique de croissance de grain des péridotites. Il est ensuite montré que l’introduction de phases secondaires telles que les pyroxènes et le spinelle permet de ralentir la croissance mais ne suffit pas à obtenir des cinétiques cohérentes avec les contraintes naturelles. Finalement il est proposé que les impuretés jouent un rôle important dans la cinétique de croissance des roches mantelliques et que leur prise en compte permet de concilier les contraintes venant des expériences de laboratoire et des observations naturelles.Dans une deuxième grande partie, le modèle constitutif utilisé pour décrire le comportement mécanique de l’olivine dans un cadre de plasticité cristalline est présenté. La manipulation des différents tenseurs dans ce cadre numérique repose sur la construction de bases tensorielles particulières tenant compte des symétries du cristal et permettant l’utilisation d’une élasticité anisotropede manière transparente et naturelle. La formulation mixte EF vitesse-pression est également modifiée pour tenir compte de l’anisotropie élastique. Cette manière de décrire la déformation est ensuite enrichie d’un mécanisme de relaxation sensé représenter les mécanismes, autres que le glissement de dislocation, accommodant la déformation dans les polycristaux d’olivine. Cette description est alors couplée avec le formalisme LS pour simuler les évolutions microstructurales d’un agrégat d’olivine durant la déformation. Ce cadre numérique est enfin utilisé pour étudier la localisation de la déformation, dans les polycristaux d’olivine, par différents types de zone de faiblesse pré-existantes.Finalement, les limites et les perspectives de développement du formalisme numérique pour aboutir à une description fidèle des évolutions microstructurales d’une roche mantellique dans des conditions thermomécaniques de la lithosphère sont discutées
This thesis aims at simulating the microstructural evolutions of upper mantle rocks under thermomechanical conditions representative of the Earth’s lithosphere. Indeed, the mechanical behavior of these rocks controls, at first order, the rheology of the lithosphere and thus of the tectonic plates.The tools used and developed in this work are based on the level-set (LS) formalism allowing an implicit description of the grain boundaries and the modelling of grain boundary migration (GBM) at the polycrystal scale. Thus, the microstructural evolutions are simulated in a robust and efficient finite element (FE) framework allowing a coupling with crystal plasticity (CP) calculations which allows to describe the mechanical behavior of the rock.A first large part of this thesis is devoted to the deformation-free grain growth (GG) in peridotites. Firstly we show that the GG kinetics of olivine (major phase of peridotites), considering only capillarity force, is not in agreement with the natural constraints on the GG kinetics of peridotites. Secondly, it is shown that the introduction of secondary phases such as pyroxenes and spinels can slow GG but is not sufficient to reach kinetics compatible with natural constraints. Finally, it is proposed that impurities play an important role in the GG kinetics of mantel rocks and that taking them into account allows reconciling the constraints coming from laboratory experiments and natural observations.In a second part of the thesis, the constitutive model used to describe the mechanical behavior of olivine in a CP framework is presented. The manipulation of the different tensors in this numerical framework is based on the construction of particular tensor bases considering the symmetries of the crystal and allowing the use of anisotropic elasticity in a straightforward and natural way. The mixed FE velocity-pressure formulation is also modified to take into account the elastic anisotropy. This way of describing the deformation is then enriched with a relaxation mechanism supposed to represent the various processes, other than dislocation glide, accommodating deformation in olivine polycrystals. This description is then coupled with the LS formalism to simulate the microstructural evolutions of an olivine aggregate during deformation. This numerical framework is finally used to study the strain localization in olivine polycrystals along different types of pre-existing shear zones.Finally, the limits and perspectives of the development of numerical formalism to arrive at a faithful description of the microstructural evolutions of a mantle rocks within the lithospheric thermomechanical conditions are discussed

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Al-Harbi, Hamad F. « Crystal plasticity finite element simulations using discrete Fourier transforms ». Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/51788.

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Crystallographic texture and its evolution are known to be major sources of anisotropy in polycrystalline metals. Highly simplified phenomenological models cannot usually provide reliable predictions of the materials anisotropy under complex deformation paths, and lack the fidelity needed to optimize the microstructure and mechanical properties during the production process. On the other hand, physics-based models such as crystal plasticity theories have demonstrated remarkable success in predicting the anisotropic mechanical response in polycrystalline metals and the evolution of underlying texture in finite plastic deformation. However, the integration of crystal plasticity models with finite element (FE) simulations tools (called CPFEM) is extremely computationally expensive, and has not been adopted broadly by the advanced materials development community. The current dissertation has mainly focused on addressing the challenges associated with integrating the recently developed spectral database approach with a commercial FE tool to permit computationally efficient simulations of heterogeneous deformations using crystal plasticity theories. More specifically, the spectral database approach to crystal plasticity solutions was successfully integrated with the implicit version of the FE package ABAQUS through a user materials subroutine, UMAT, to conduct more efficient CPFEM simulations on both fcc and bcc polycrystalline materials. It is observed that implementing the crystal plasticity spectral database in a FE code produced excellent predictions similar to the classical CPFEM, but at a significantly faster computational speed. Furthermore, an important application of the CPFEM for the extraction of crystal level plasticity parameters in multiphase materials has been demonstrated in this dissertation. More specifically, CPFEM along with a recently developed data analysis approach for spherical nanoindentation and Orientation Imaging Microscopy (OIM) have been used to extract the critical resolved shear stress of the ferrite phase in dual phase steels. This new methodology offers a novel efficient tool for the extraction of crystal level hardening parameters in any single or multiphase materials.

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Kabir, Saiful. « Finite element modelling of photonic crystal fibres ». Thesis, City University London, 2007. http://openaccess.city.ac.uk/8592/.

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Photonic crystal fibre (PCF), a new kind of optical fibre, has many air-holes in their cross-section and has potential applications to new optical communication systems. The main objective of this research is the modelling of photonic crystal fibre to identify the fundamental and higher order quasi-TE and TM modes with square, ,rectangular and circular air holes in a square and hexagonal matrix, by using a rigorous full-vectorial H-field based finite element method (FEM). Besides the modal solutions of the effective indices, mode field profiles, spot sizes, modal hybridness, polarization beat length and group velocity dispersion values for equal and unequal air holes; research was carried out to optimize and design highly birefringent PCF. The variation of modal birefringence is shown through the effect of hole diameters, air hole arrangement, structural asymmetry, operating wavelength, and pitch-distance. Birefringence was enhanced by breaking the structural symmetry and this was verified by using unequal air holes. The diameter of two air holes and four air holes in the first ring was changed to break the rotational symmetry and a comparison between the two designs is made in this work. In this work, highly birefringent PCF is designed with higher operating wavelength, larger d2/A value, lower pitch length for a given structural asymmetry. It is identified that birefringence value increases rapidly when d2 is much larger than d. At lower pitch value, one of the highest birefringence values reported so far at wavelertgth of 1.55 J.Jm for an asymmetric PCF using circular air holes. A single polarization guide PCF structure is also achieved. In this study, it has been identified that for fixed d/A and d2/A value, as operating wavelength is increased, birefringence increases significantly. It can also be identified that for higher d/A values, birefringence changes rapidly with A as their corresponding cutoff condition also approaches. One important validation of this work is the existence of modal birefringence for PCF with six-fold rotational symmetry. It is shown that birefringence value of a simple PCF incorporating circular holes but of different diameters is high compared to polarization maintaining Panda or Bow-tie fibres. This research also aims to investigate the modal leakage losses of PCF, by using a semi-vectorial beam propagation method (BPM) based on the versatile FEM. The robust perfectly matched layer (PML) boundary condition has been introduced to the modal solution approach. The effects of d2/A, operating wavelength and number of air holes have been thoroughly detailed and explained. In this study, it has been identified that the confinement loss decreases significantly with the increased number of rings, lower operating wavelength and lower d2/A value. For special case, PCF with large spot-size provides higher leakage loss.

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Hiett, Ben. « Photonic crystal modelling using finite element analysis ». Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274031.

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Alankar, Alankar. « Development of a 3D microstructure sensitive crystal plasticity model for aluminum ». Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/A_Alankar_020910.pdf.

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Livres sur le sujet "Crystal Plasticity Finite Element Modelling"

Roters, Franz, Philip Eisenlohr, Thomas R. Bieler et Dierk Raabe. Crystal Plasticity Finite Element Methods. Weinheim, Germany : Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631483.

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library, Wiley online, dir. Crystal plasticity finite element methods in materials science and engineering. Weinheim : Wiley-VCH, 2010.

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Bieler, Thomas R., Dierk Raabe, Franz Roters et Philip Eisenlohr. Crystal Plasticity Finite Element Methods : In Materials Science and Engineering. Wiley & Sons, Incorporated, John, 2011.

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Bieler, Thomas R., Dierk Raabe, Franz Roters et Philip Eisenlohr. Crystal Plasticity Finite Element Methods : In Materials Science and Engineering. Wiley & Sons, Incorporated, John, 2011.

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Chapitres de livres sur le sujet "Crystal Plasticity Finite Element Modelling"

Li, He Jie, Jing Tao Han, Zheng Yi Jiang, Hua Chun Pi, Dong Bin Wei et Anh Kiet Tieu. « Crystal Plasticity Finite Element Modelling of BCC Deformation Texture in Cold Rolling ». Dans Frontiers in Materials Science and Technology, 251–54. Stafa : Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/0-87849-475-8.251.

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Raabe, Dierk, et Richard C. Becker. « Coupling of a Crystal Plasticity Finite Element Model with a Probabilistic Cellular Automaton for Simulating Primary Static Recrystallization in Aluminum ». Dans Microstructures, Mechanical Properties and Processes - Computer Simulation and Modelling, 1–8. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606157.ch1.

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Rodič, T., B. Štok, F. Gologranc et D. R. J. Owen. « Finite Element Modelling of a Radial Forging Process ». Dans Advanced Technology of Plasticity 1987, 1065–72. Berlin, Heidelberg : Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-662-11046-1_49.

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Kalidindi, Surya R. « Micro-Mechanical Finite Element Models for Crystal Plasticity ». Dans Continuum Scale Simulation of Engineering Materials, 529–42. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527603786.ch26.

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Roters, Franz. « The Texture Component Crystal Plasticity Finite Element Method ». Dans Continuum Scale Simulation of Engineering Materials, 561–72. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527603786.ch28.

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Corradi, L. « Finite Element Modelling of the Elastic-Plastic Problem ». Dans Mathematical Programming Methods in Structural Plasticity, 255–91. Vienna : Springer Vienna, 1990. http://dx.doi.org/10.1007/978-3-7091-2618-9_14.

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Ohashi, Tetsuya. « Dislocation Density-Based Modeling of Crystal Plasticity Finite Element Analysis ». Dans Handbook of Mechanics of Materials, 1213–38. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-6884-3_74.

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Ohashi, Tetsuya. « Dislocation Density-Based Modeling of Crystal Plasticity Finite Element Analysis ». Dans Handbook of Mechanics of Materials, 1–26. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6855-3_74-1.

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Pastor, M. « Generalized Plasticity Modelling of Saturated Sand Behaviour under Earthquake Loading ». Dans The finite element method in the 1990’s, 119–32. Berlin, Heidelberg : Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-662-10326-5_13.

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Massoni, E., M. Bellet, J. L. Chenot, J. M. Detraux et C. de Baynast. « A Finite Element Modelling for Deep Drawing of Thin Sheet in Automotive Industry ». Dans Advanced Technology of Plasticity 1987, 719–25. Berlin, Heidelberg : Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-662-11046-1_5.

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Actes de conférences sur le sujet "Crystal Plasticity Finite Element Modelling"

CHEN, Y. P., W. B. LEE, S. TO et H. WANG. « FINITE ELEMENT MODELLING OF MICRO-CUTTING PROCESSES FROM CRYSTAL PLASTICITY ». Dans Proceedings of the 9th AEPA2008. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789814261579_0090.

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Gu, S. D., J. P. Zhao, T. Xu et Y. H. Zhang. « A Method of Crystal Plasticity Finite Element Modelling in BCC, FCC and HCP Metals ». Dans 2020 6th International Conference on Mechanical Engineering and Automation Science (ICMEAS). IEEE, 2020. http://dx.doi.org/10.1109/icmeas51739.2020.00055.

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Li, Dong-Feng, Brian Golden et Noel P. O’Dowd. « Modelling of Micro-Plasticity Evolution in Crystalline Materials ». Dans ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97233.

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In this work, a micromechanical finite element model is presented to investigate micro-plasticity evolution in crystalline materials, with a comprehensive consideration of microstructural interactions, including morphology-based intragranular stress-strain response and the strain gradient induced scale effect. A dislocation-mechanics based crystal plasticity formulation has been employed to account for slip based inelastic deformation. A polycrystalline model has been constructed using the Voronoi tessellation technique to represent the microstructure of a martensitic power plant steel, P91. The model has been validated through a uniaxial tensile test. The effects of strain gradient have been examined at both macroscopic and microscopic levels and the importance of accounting for strain gradient effects in the prediction of local deformation states is discussed for P91.

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Li, Dong-Feng, et Noel P. O’Dowd. « Investigating Ductile Failure at the Microscale in Engineering Steels : A Micromechanical Finite Element Model ». Dans ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78802.

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In this study, we present a microstructure-based micromechanical model to quantify failure mechanisms in engineering steels. Crystal plasticity at the microscale, governed by crystallographic slip, is explicitly taken into account in the frame-work of continuum mechanics. Furthermore, it is assumed that material damage at the microscale is controlled by the accumulated equivalent plastic strain, such that failure occurs once this strain exceeds a threshold. Both single- and poly-crystalline materials containing sufficient numbers of grains are investigated under a representative macroscopic loading. The calibration of the present model relies on uniaxial tensile test data. Both austenitic stainless steels (such as 316H) and martensitic steels (such as P91) are examined to illustrate the application of the method. The micromechanical modelling provides insights into understanding of the mechanical response at the microscale in engineering steels.

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Zhao, Xinglong, Joa˜o Quinta da Fonseca, Andrew Sherry et David Lidbury. « Grain-Scale Heterogeneity Effect on Mechanistic Modelling of Cleavage Fracture of a Ferritic RPV Steel Forging Material ». Dans ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61569.

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Improving brittle fracture prediction is crucial for structural integrity assessment. In current safety assessments, fracture mechanics treats polycrystalline steels as homogeneous continua. In reality, deformation of structural steels is heterogeneous. Part of this heterogeneity is due to the elastic and plastic anisotropy of their constituent (often randomly orientated) grains. This paper will compare the predicted failure stresses from tensile tests performed on a ferritic pressure vessel steel using the crystal plasticity finite element approach alongside measured carbide distribution and classical Beremin cleavage model. Available tensile data of 22NiMoCr37 steel at low temperature (−91°C and −154°C) were analysed using Bridgman solutions to account for the necking effect on the stress state at the centre of necking where brittle cracking initiates. This stress state imposed on representative volume element (RVE) made up of 10×10×10 randomly orientated grains, whose deformation is simulated using crystal plasticity finite element modelling (CPFEM). Randomly distributed carbides were produced based on the measured carbide size distribution and density for this steel. By assuming carbides as Griffith microcracks, the cleavage fracture stress in each grain can be assessed based the maximum principal stress on the cleavage crystal plane and an assumed surface energy. By repeating the random carbide distribution 1,000 times, brittle fracture probability can be calculated. Detailed examination shows that the above approach is actually a verification of the BEREMIN local approach model for cleavage fracture. The modelling results were compared with the available ductility data at −91°C and the interpolated ductility data at −154°C at the centre of necking. It is foreseen that this approach will lead to improvements in brittle fracture modelling in heterogeneous ferritic steels by introducing realistic surface energies and real defect distributions in specific materials, when used alongside the CPFEM submodelling approach.

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Golden, Brian, Dongfeng Li et Noel O’Dowd. « Microstructural Modelling of P91 Martensitic Steel Under Uniaxial Loading Conditions ». Dans ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97514.

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The changing face of power generation requires an improved understanding of the deformation and failure response of power plant materials. Important insights can be obtained through microstructurally motivated modelling studies. This paper deals with the comparisons of predictions of the mechanical response of a power plant steel (P91), obtained from a model with a measured microstructure with those obtained from a numerically simulated microstructure. Electron backscatter diffraction (EBSD) is employed to obtain the orientation of the martensitic grain structure of the steel. This information is incorporated within a representative volume element (RVE) to represent the material microstructure. A non-linear, rate dependent, finite strain crystal plasticity model is used to represent the deformation of the material, with the orientation of each finite-element integration point determined from the EBSD analysis. The deformation under uniaxial tension is analysed. Due to the inhomogeneous microstructure strong strain gradients are generated within the RVE even under remote homogenous strain states. It is seen that peak stress/strain states are associated with particular features of the microstructure. The results taken from the model are compared with those obtained with an equiaxed microstructure generated using the Voronoi tessellation method.

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Simonovski, I., L. Cizelj, T. J. Marrow, J. Quinta da Fonseca et A. King. « Towards Modelling Intergranular Stress-Corrosion Cracks Using Experimentally Obtained Grain Topologies ». Dans ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77883.

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Predicting the effects of material aging in view of development of intergranular damage is of particular importance in a number of nuclear installations and especially in structural integrity assessments of critical components in energy generating power plants. Since the damage is initialized on small length scales, detailed multiscale models should be employed to tackle the problem. However, the complexity of such models is high due to the need of incorporating microstructural features. In line of this the research group from Jozˇef Stefan Institute and The University of Manchester joined forces and knowledge in development of such detailed multiscale models. The basic idea was to pair the knowledge of advanced experimental techniques of The University of Manchester group with the knowledge of advanced microstructure modelling techniques of the group at Jozˇef Stefan Institute. The presented paper proposes a novel approach for intergranular crack modelling whereby a state-of-the-art X-ray diffraction contrast tomography technique is used to obtain 3D topologies and crystallographic orientations of individual grains in a stainless steel wire and intergranular stress corrosion cracks. As measured topologies and orientations of individual grains are then reconstructed within a finite element model and coupled with advanced constitutive material behaviour: anisotropic elasticity and crystal plasticity. Due to the extreme complexity of grain topologies, transferring this information into the finite element model presents a challenging task. The feasibility of the proposed approach is presented. Difficulties in building a finite element model are discussed. Preliminary results of the analyses are also given.

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Golden, Brian J., Dong-Feng Li, Peter Tiernan, Stephen Scully et Noel P. O’Dowd. « Deformation Characteristics of a High Chromium, Power Plant Steel at Elevated Temperatures ». Dans ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45487.

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The changing face of power generation requires an improved understanding of the deformation and failure response of materials that are employed in power plants. Important insights can be obtained through microstructurally motivated modelling studies. With the drive for increased efficiency, there is a corresponding drive towards increasing operating temperatures in conventional power plant. With these increasing temperatures, and with the increased flexibility required of modern power plant working in a mixed energy economy, more robust material testing and modelling tools are required to accurately predict the response of power plant steels. This works deals with the development of a material model for a martensitic steel, P91, relevant to the range of temperatures typically seen in a modern power plant. High temperature (20, 400, 500, 600°C) tensile testing at various strain rates was carried out the steel. Tests were taken to failure and the stress strain response recorded. Electron backscatter diffraction (EBSD) is employed to determine the complex microstructure of the P91 material. This information is incorporated within a representative volume element (RVE) and a nonlinear, rate dependent, finite strain crystal plasticity model used to represent the deformation of the material. The material model was calibrated to each temperature and strain rate to give a robust physically based model that has been fully validated through experimental data.

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Cizelj, L., et I. Simonovski. « Multiscale Assessment of Random Polycrystalline Aggregates With Short Cracks ». Dans 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89623.

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The complete understanding of the incubation and growth of microstructurally short cracks is still somewhat beyond the present state-of-the-art explanations. A good example is the intergranular stress corrosion cracking of Inconel 600 in high-temperature water. An effort was therefore made by the authors to construct a computational model of the crack growth kinetics at the grain-size scale. The main idea is to divide continuum (e.g., polycrystalline aggregate) into a set of sub-continua (grains). Random grain structure is modelled using Voronoi-Dirichlet tessellation. Each grain is assumed to be a monocrystal with random orientation of the crystal lattice. Elastic behaviour of grains is assumed to be anisotropic. Crystal plasticity is used to describe (small to moderate) plastic deformation of monocrystal grains. Explicit geometrical modelling of grain boundaries and triple points allows for the development of the incompatible strains along the grain boundaries and at triple points. Finite element method (ABAQUS) is used to obtain numerical solutions of strain and stress fields. The analysis is currently limited to two-dimensional models. Numerical examples illustrate analysis of about one grain boundary long transgranular cracks. In particular, the dependence of crack tip displacements on the random orientation of neighbouring grains is studied. The limited number of calculations performed indicates that the incompatibility strains, which develop along the boundaries of randomly oriented grains, significantly influence the local stress fields and therefore also the crack tip displacements. First attempts are also made to quantify the preferential growth directions of cracks crossing the discontinuities (e.g., grain boundary).

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LEE, MYOUNG GYU, ROBERT H. WAGONER et SUNG-JOON KIM. « COMPARATIVE STUDY OF SINGLE CRYSTAL CONSTITUTIVE EQUATIONS FOR CRYSTAL PLASTICITY FINITE ELEMENT ANALYSIS ». Dans Proceedings of the 9th AEPA2008. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789814261579_0003.

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Rapports d'organisations sur le sujet "Crystal Plasticity Finite Element Modelling"

Sam, D. D., et W. E. King. Multilength-scale modeling : Crystal-plasticity models in implicit finite element codes. Office of Scientific and Technical Information (OSTI), mars 1996. http://dx.doi.org/10.2172/268364.

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Rovinelli, A., M. C. Messner, Guosheng Ye et T. L. Sham. Initial study of notch sensitivity of Grade 91 using mechanisms motivated crystal plasticity finite element method. Office of Scientific and Technical Information (OSTI), septembre 2019. http://dx.doi.org/10.2172/1603666.

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