Experiment-based validation and uncertainty quantification of coupled multi-scale plasticity models

2016 ◽  
Vol 12 (1) ◽  
pp. 151-176 ◽  
Author(s):  
Garrison Stevens ◽  
Sez Atamturktur ◽  
Ricardo Lebensohn ◽  
George Kaschner
Keyword(s):  
Coupled Model ◽  
Material Behavior ◽  
Radioactive Material ◽  
Material Structure ◽  
Coupled Models ◽  
Content Type ◽  
Strongly Coupled ◽  
Multi Scale ◽  
Macro Scale ◽  
Meso Scale

Purpose – Highly anisotropic zirconium is a material used in the cladding of nuclear fuel rods, ensuring containment of the radioactive material within. The complex material structure of anisotropic zirconium requires model developers to replicate not only the macro-scale stresses but also the meso-scale material behavior as the crystal structure evolves; leading to strongly coupled multi-scale plasticity models. Such strongly coupled models can be achieved through partitioned analysis techniques, which couple independently developed constituent models through an iterative exchange of inputs and outputs. Throughout this iterative process, biases, and uncertainties inherent within constituent model predictions are inevitably transferred between constituents either compensating for each other or accumulating during iterations. The paper aims to discuss these issues. Design/methodology/approach – A finite element model at the macro-scale is coupled in an iterative manner with a meso-scale viscoplastic self-consistent model, where the former supplies the stress input and latter represents the changing material properties. The authors present a systematic framework for experiment-based validation taking advantage of both separate-effect experiments conducted within each constituent’s domain to calibrate the constituents in their respective scales and integral-effect experiments executed within the coupled domain to test the validity of the coupled system. Findings – This framework developed is shown to improve predictive capability of a multi-scale plasticity model of highly anisotropic zirconium. Originality/value – For multi-scale models to be implemented to support high-consequence decisions, such as the containment of radioactive material, this transfer of biases and uncertainties must be evaluated to ensure accuracy of the predictions of the coupled model. This framework takes advantage of the transparency of partitioned analysis to reduce the accumulation of errors and uncertainties.

Investigation and multi-scale optimization design of woven composite cut-out structures

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Duc Hai Nguyen ◽  
Hu Wang ◽  
Fan Ye ◽  
Wei Hu
Keyword(s):  
Mechanical Properties ◽  
Composite Structures ◽  
Optimization Design ◽  
Material Behavior ◽  
Efficient Global Optimization ◽  
Support Vector ◽  
Woven Composite ◽  
Content Type ◽  
Multi Scale ◽  
Ply Orientation

Purpose The purpose of this paper is to investigate the mechanical properties’ behaviors of woven composite cut-out structures with specific parameters. Because of the complexity of micro-scale and meso-scale structure, it is difficult to accurately predict the mechanical material behavior of woven composites. Numerical simulations are increasingly necessary for the design and optimization of test procedures for composite structures made by the woven composite. The results of the proposed method are well satisfied with the results obtained from the experiment and other studies. Moreover, parametric studies on different plates based on the stacking sequences are investigated. Design/methodology/approach A multi-scale modeling approach is suggested. Back-propagation neural networks (BPNN), radial basis function (RBF) and least square support vector regression are integrated with efficient global optimization (EGO) to reduce the weight of assigned structure. Optimization results are verified by finite element analysis. Findings Compared with other similar studies, the advantage of the suggested strategy uses homogenized properties behaviors with more complex analysis of woven composite structures. According to investigation results, it can be found that 450/−450 ply-orientation is the best buckling load value for all the cut-out shape requirements. According to the optimal results, the BPNN-EGO is the best candidate for the EGO to optimize the woven composite structures. Originality/value A multi-scale approach is used to investigate the mechanical properties of a complex woven composite material architecture. Buckling of different cut-out shapes with the same area is surveyed. According to investigation, 45°/−45° ply-orientation is the best for all cut-out shapes. Different surrogate models are integrated in EGO for optimization. The BPNN surrogate model is the best choice for EGO to optimization difficult problems of woven composite materials.

Application of an EMMS Model for Bubbly Fluidized Bed

2017 ◽  
Vol 372 ◽  
pp. 170-179
Author(s):  
Daniel A. Kestering ◽  
Flavia F.S. Zinani ◽  
George C. Bleyer
Keyword(s):  
Multi Scale ◽  
Macro Scale ◽  
Scale Models ◽  
Fluid Bed ◽  
Computational Fluid Dynamics Cfd ◽  
Geldart Groups ◽  
Coarse Grids ◽  
Individual Particles ◽  
Meso Scale ◽  
Good Agreement

In computational fluid dynamics (CFD) of fluidization processes, the modeling of drag between fluid and particles has a direct effect on the results. The EMMS (Energy Minimization Multi-Scale) models are based on the micro-scale of individual particles and the macro scale of equipment to model the meso-scale phenomena related to particle clustering, which directly affect the drag between fluid and particles. The EMMS/bubbling model was introduced as a change from the classic EMMS model to specific bubbling fluid bed conditions. The present work aims to apply the EMMS/bubbling model in the CFD of Geldart-D particles fluidized by air. The results were compared with results from the literature. It was observed that, for particles of Geldart groups A and B, the results using the EMMS/bubbling model agreed well with the literature. The CFD results for Geldart-D particles showed good agreement with the literature results for this method using coarse grids.

scholarly journals Bayesian stochastic multi-scale analysis via energy considerations

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhammad S. Sarfaraz ◽  
Bojana V. Rosić ◽  
Hermann G. Matthies ◽  
Adnan Ibrahimbegović
Keyword(s):  
Nonlinear Approximation ◽  
Computational Cost ◽  
Cementitious Materials ◽  
Model Errors ◽  
Stored Energy ◽  
Standard Material ◽  
Multi Scale ◽  
Macro Scale ◽  
Optimal Material ◽  
Meso Scale

AbstractMulti-scale processes governed on each scale by separate principles for evolution or equilibrium are coupled by matching the stored energy and dissipation in line with the Hill-Mandel principle. We are interested in cementitious materials, and consider here the macro- and meso-scale behaviour of such a material. The accurate representations of stored energy and dissipation are essential for the depiction of irreversible material behaviour, and here a Bayesian approach is used to match these quantities on different scales. This is a probabilistic upscaling and as such allows to capture, among other things, the loss of resolution due to scale coarsening, possible model errors, localisation effects, and the geometric and material randomness of the meso-scale constituents in the upscaling. On the coarser (macro) scale, optimal material parameters are estimated probabilistically for certain possible behaviours from the class of generalised standard material models by employing a nonlinear approximation of Bayes’s rule. To reduce the overall computational cost, a model reduction of the meso-scale simulation is achieved by combining unsupervised learning techniques based on a Bayesian copula variational inference with functional approximation forms.

An Efficient Multi-Scale Modeling Method that Reveals Coupled Effects Between Surface Roughness and Roll-Stack Deformation in Cold Sheet Rolling

2021 ◽  
pp. 1-53
Author(s):  
Feng Zhang ◽  
Arif S Malik
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Rough Surface ◽  
Material Behavior ◽  
Sheet Rolling ◽  
Elastic Plastic ◽  
Multi Scale ◽  
Macro Scale ◽  
Surface Contact ◽  
Rough Surface Contact

Abstract In thin-gauge cold rolling of metal sheet, the surface roughness of work-rolls is known to affect the rolled sheet surface morphology, the required rolling load, and the roll wear. While modeling of rough surfaces using statistical asperity theory has been widely applied to problems involving semi-infinite solids, the application of asperity distributions and their elastic-plastic behavior has not been considered in roll-stack models for cold sheet rolling. In this work, a simplified-mixed finite element method (SM-FEM) is combined with statistical elastic-plastic asperity theory to study contact interference and coupling effects between a rough work-roll surface and the roll-stack mechanics in cold sheet rolling. By mixing equivalent rough-surface contact foundations, Hertz foundations, and Timoshenko beam stiffness, an approach is created to efficiently model interactions between the micro-scale asperities and the macro-scale roll-stack deformation. Nonlinearities from elastic-plastic material behavior of the asperities and the sheet, as well as changing contact conditions along the roll length, are also accommodated. Performance of the multi-scale SM-FEM approach is made by comparison to a continuum finite element virtual material model. 3D studies for a 4-high mill reveal new multi-scale coupling behaviors, including non-uniform roughness transfer, and perturbations to the sheet thickness ‘crown’ and contact force profiles. The described multi-scale SM-FEM approach is general and applies to rough surface contact problems involving plates and shear-deformable beams having multiple contact interfaces and arbitrary surface profiles.

Multi-scale finite element modeling of 3D printed structures subjected to mechanical loads

2018 ◽  
Vol 24 (1) ◽  
pp. 177-187 ◽  
Author(s):  
Dalia Calneryte ◽  
Rimantas Barauskas ◽  
Daiva Milasiene ◽  
Rytis Maskeliunas ◽  
Audrius Neciunas ◽  
...  
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Computational Models ◽  
Three Dimensional ◽  
Structural Response ◽  
Content Type ◽  
Multi Scale ◽  
Macro Scale ◽  
Internal Constitution ◽  
3D Printed

Purpose The purpose of this paper is to investigate the influence of geometrical microstructure of items obtained by applying a three-dimensional (3D) printing technology on their mechanical strength. Design/methodology/approach Three-dimensional printed items (3DPI) are composite structures of complex internal constitution. The buildup of the finite element (FE) computational models of 3DPI is based on a multi-scale approach. At the micro-scale, the FE models of representative volume elements corresponding to different additive layer heights and different thicknesses of extruded fibers are investigated to obtain the equivalent non-linear nominal stress–strain curves. The obtained results are used for the creation of macro-scale FE models, which enable to simulate the overall structural response of 3D printed samples subjected to tensile and bending loads. Findings The validation of the models was performed by comparing the computed results against the experimental ones, where satisfactory agreement has been demonstrated within a marked range of thicknesses of additive layers. Certain inadequacies between computed against experimental results were observed in cases of thinnest and thickest additive layers. The principle explanation of the reasons of inadequacies takes into account the poorer quality of mutual adhesion in case of very thin extruded fibers and too-early solidification effect. Originality/value Flexural and tensile experiments are simulated by FE models that are created with consideration to microstructure of 3D printed samples.

Multi‐scale modelling of heterogeneous structures with inelastic constitutive behavior

2009 ◽  
Vol 26 (1/2) ◽  
pp. 6-28 ◽  
Author(s):  
Rainer Niekamp ◽  
Damijan Markovic ◽  
Adnan Ibrahimbegovic ◽  
Hermann G. Matthies ◽  
Robert L. Taylor
Keyword(s):  
The Finite Element Method ◽  
Computational Tools ◽  
Content Type ◽  
Strongly Coupled ◽  
Multi Scale ◽  
Heterogeneous Structures ◽  
Software Product ◽  
Scale Modelling ◽  
Template Library ◽  
Software Coupling

PurposeThe purpose of this paper is to consider the computational tools for solving a strongly coupled multi‐scale problem in the context of inelastic structural mechanics.Design/methodology/approachIn trying to maintain the highest level of generality, the finite element method is employed for representing the microstructure at this fine scale and computing the solution. The main focus of this work is the implementation procedure which crucially relies on a novel software product developed by the first author in terms of component template library (CTL).FindingsThe paper confirms that one can produce very powerful computational tools by software coupling technology described herein, which allows the class of complex problems one can successfully tackle nowadays to be extended significantly.Originality/valueThis paper elaborates upon a new multi‐scale solution strategy suitable for highly non‐linear inelastic problems.

Phenomena of Multicale Fracture of Brittle Materials and its Application to Teaching in Strength Theory

2011 ◽  
Vol 243-249 ◽  
pp. 2084-2090 ◽  
Author(s):  
Li Wang ◽  
Da Hu Rui ◽  
Jian Hui Yang
Keyword(s):  
Brittle Material ◽  
Tensile Strain ◽  
Failure Process ◽  
Strength Theory ◽  
Multi Scale ◽  
Scale Size ◽  
Micro Cracks ◽  
Macro Scale ◽  
Shearing Strain ◽  
Meso Scale

Multi-scale science is the challenge and opportunity of science in the 21th century, and turbulence of liquid and fracture of solid will be the classical problems of multi-scale mechanics. The failure process of brittle materials displayed a multi-scale mechanics feature that amounts of micro damages grow large trans-scale and nonlinear and evolve to a macro catastrophic transition in the end. So, the concepts of scale and hierarchy of material are inescapable in strength theory to be used explaining solid fracture, it is the main puzzle of the strength theory at present. In the paper, in order to show the phenomena of multi-scale fracture, numeric method is used to simulate the failure process of brittle material, during which micro cracks initiate, grow large, aggregate and in the end form a run-through fracture band in the sample. The result of the numeric simulation shows that the micro cracks of a meso-scale size initiate due to tensile strain and the sample of a macro-scale size breaks down due to tensile-shearing strain under uniaxial tensile or due to compression-shearing strain under uniaxial compression. It powerfully disabused the puzzles in teaching strength theory of brittle material. The further discussion concluded that for a brittle material grain of meso-scale size, the theory of Maximum Tensile Strain is reasonable in explaining the strength, as for a brittle material sample of a macro-scale size, the mohr-columb theory is reasonable for its strength owing to the two important factors of cohesive strength and friction factorwere introduced.

Influence of microstructure morphology on multi-scale modeling of low-alloyed TRIP-steels

2018 ◽  
Vol 35 (2) ◽  
pp. 499-528 ◽  
Author(s):  
Stefan Prüger ◽  
Ashutosh Gandhi ◽  
Daniel Balzani
Keyword(s):  
Volume Fraction ◽  
Measurement Techniques ◽  
Content Type ◽  
Systematic Assessment ◽  
Microstructural Parameters ◽  
Multi Scale ◽  
Scale Modeling ◽  
Macro Scale ◽  
Microstructure Morphology ◽  
The Impact

Purpose The purpose of this study is to quantify the impact of the variation of microstructural features on macroscopic and microscopic fields. The application of multi-scale methods in the context of constitutive modeling of microheterogeneous materials requires the choice of a representative volume element (RVE) of the considered microstructure, which may be based on some idealized assumptions and/or on experimental observations. In any case, a realistic microstructure within the RVE is either computationally too expensive or not fully accessible by experimental measurement techniques, which introduces some uncertainty regarding the microstructural features. Design/methodology/approach In this paper, a systematical variation of microstructural parameters controlling the morphology of an RVE with an idealized microstructure is conducted and the impact on macroscopic quantities of interest as well as microstructural fields and their statistics is investigated. The study is carried out under macroscopically homogeneous deformation states using the direct micro-macro scale transition approach. Findings The variation of microstructural parameters, such as inclusion volume fraction, aspect ratio and orientation of the inclusion with respect to the overall loading, influences the macroscopic behavior, especially the micromechanical fields significantly. Originality/value The systematic assessment of the impact of microstructural parameters on both macroscopic quantities and statistics of the micromechanical fields allows for a quantitative comparison of different microstructure morphologies and a reliable identification of microstructural parameters that promote failure initialization in microheterogeneous materials.

scholarly journals Effects of multi-scale heterogeneity on the simulated evolution of ice-rich permafrost lowlands under a warming climate

2021 ◽  
Vol 15 (3) ◽  
pp. 1399-1422
Author(s):  
Jan Nitzbon ◽  
Moritz Langer ◽  
Léo C. P. Martin ◽  
Sebastian Westermann ◽  
Thomas Schneider von Deimling ◽  
...  
Keyword(s):  
Climate Warming ◽  
Land Surface ◽  
Landscape Dynamics ◽  
Permafrost Degradation ◽  
Subgrid Scale ◽  
Feedback Mechanisms ◽  
Multi Scale ◽  
Macro Scale ◽  
Ice Wedge ◽  
Meso Scale

Abstract. In continuous permafrost lowlands, thawing of ice-rich deposits and melting of massive ground ice lead to abrupt landscape changes called thermokarst, which have widespread consequences on the thermal, hydrological, and biogeochemical state of the subsurface. However, macro-scale land surface models (LSMs) do not resolve such localized subgrid-scale processes and could hence miss key feedback mechanisms and complexities which affect permafrost degradation and the potential liberation of soil organic carbon in high latitudes. Here, we extend the CryoGrid 3 permafrost model with a multi-scale tiling scheme which represents the spatial heterogeneities of surface and subsurface conditions in ice-rich permafrost lowlands. We conducted numerical simulations using stylized model setups to assess how different representations of micro- and meso-scale heterogeneities affect landscape evolution pathways and the amount of permafrost degradation in response to climate warming. At the micro-scale, the terrain was assumed to be either homogeneous or composed of ice-wedge polygons, and at the meso-scale it was assumed to be either homogeneous or resembling a low-gradient slope. We found that by using different model setups and parameter sets, a multitude of landscape evolution pathways could be simulated which correspond well to observed thermokarst landscape dynamics across the Arctic. These pathways include the formation, growth, and gradual drainage of thaw lakes; the transition from low-centred to high-centred ice-wedge polygons; and the formation of landscape-wide drainage systems due to melting of ice wedges. Moreover, we identified several feedback mechanisms due to lateral transport processes which either stabilize or destabilize the thermokarst terrain. The amount of permafrost degradation in response to climate warming was found to depend primarily on the prevailing hydrological conditions, which in turn are crucially affected by whether or not micro- and/or meso-scale heterogeneities were considered in the model setup. Our results suggest that the multi-scale tiling scheme allows for simulating ice-rich permafrost landscape dynamics in a more realistic way than simplistic one-dimensional models and thus facilitates more robust assessments of permafrost degradation pathways in response to climate warming. Our modelling work improves the understanding of how micro- and meso-scale processes affect the evolution of ice-rich permafrost landscapes, and it informs macro-scale modellers focusing on high-latitude land surface processes about the necessities and possibilities for the inclusion of subgrid-scale processes such as thermokarst within their models.

scholarly journals TBRs, a methodology for the multi-scalar cartographic analysis of the distribution of plant formations

2020 ◽  
Author(s):  
Rafael Cámara Artigas ◽  
Fernando Díaz del Olmo ◽  
Jose Ramon Martinez Batlle
Keyword(s):  
Water Balance ◽  
Distribution Map ◽  
Biomass Distribution ◽  
Micro Scale ◽  
Multi Scale ◽  
Macro Scale ◽  
Bioclimatic Variables ◽  
Different Levels ◽  
Meso Scale ◽  
Scale Classification

An analytical and cartographic method of biomass distribution and plant formations at a multi-scalar level is developed based on bioclimatic variables extracted from the Thornthwaite Water Balance (WB) and the Bioclimatic Balances (BB) of Montero de Burgos & González Rebollar. As a result, a distribution map involving Types of Bioclimatic Regimens (TBR) is obtained leading to the identification of a multi-scale classification at different levels: zonal (macro-scale) with 5 types, regional (meso-scale) with 27 types, and local (micro-scale) with 162 plant formations subtypes, conditioned by lithology-soils, the relief exposure to wind or sunstroke respectively and obtained through the combination of TBR and ombroclimates.

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