The Experts below are selected from a list of 1045710 Experts worldwide ranked by ideXlab platform
Georges Cailletaud - One of the best experts on this subject based on the ideXlab platform.
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Rough surface contact analysis by means of the Finite Element Method and of a new Reduced Model
Comptes Rendus Mécanique, 2011Co-Authors: Vladislav Yastrebov, Julian Durand, Henry Proudhon, Georges CailletaudAbstract:This article presents two approaches of a normal frictionless mechanical contact between an elastoplastic material and a rigid plane: a full scale finite element analysis (FEA) and a Reduced Model. Both of them use a representative surface element (RSE) of an experimentally measured surface roughness. The full scale FEA is performed with the Finite Element code Zset using its parallel solver. It provides the reference for the Reduced Model. The ingredients of the Reduced Model are a series of responses that are calibrated by means of FEA on a single asperity and phenomenological rules to account for asperity-asperity interaction. The Reduced Model is able to predict the load-displacement curve, the real contact area and the free volume between the contacting pair during the compression of a rough surface against a rigid plane. The CPU time is a few seconds for the Reduced Model, instead of a few days for the full FEA.
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Rough surface contact analysis by means of the Finite Element Method and of a new Reduced Model
Comptes Rendus Mécanique, 2011Co-Authors: Vladislav Yastrebov, Julian Durand, Henry Proudhon, Georges CailletaudAbstract:International audienceThis article presents two approaches of a normal frictionless mechanical contact between an elastoplastic material and a rigid plane: a full scale finite element analysis (FEA) and a Reduced Model. Both of them use a representative surface element (RSE) of an experimentally measured surface roughness. The full scale FEA is performed with the Finite Element code Zset using its parallel solver. It provides the reference for the Reduced Model. The ingredients of the Reduced Model are a series of responses that are calibrated by means of FEA on a single asperity and phenomenological rules to account for asperity-asperity interaction. The Reduced Model is able to predict the load-displacement curve, the real contact area and the free volume between the contacting pair during the compression of a rough surface against a rigid plane. The CPU time is a few seconds for the Reduced Model, instead of a few days for the full FEA
Felix Otto - One of the best experts on this subject based on the ideXlab platform.
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a Reduced Model for domain walls in soft ferromagnetic films at the cross over from symmetric to asymmetric wall types
Journal of the European Mathematical Society, 2014Co-Authors: Lukas Döring, Radu Ignat, Felix OttoAbstract:We study the Landau-Lifshitz Model for the energy of multi-scale transition layers – called “domain walls” – in soft ferromagnetic films. Domain walls separate domains of constant magnetization vectors m α ∈ S that differ by an angle 2α. Assuming translation invariance tangential to the wall, our main result is the rigorous derivation of a Reduced Model for the energy of the optimal transition layer, which in a certain parameter regime confirms the experimental, numerical and physical predictions: The minimal energy splits into a contribution from an asymmetric, divergence-free core which performs a partial rotation in S by an angle 2θ, and a contribution from two symmetric, logarithmically decaying tails, each of which completes the rotation from angle θ to α in S. The angle θ is chosen such that the total energy is minimal. The contribution from the symmetric tails is known explicitly, while the contribution from the asymmetric core is analyzed in [7]. Our Reduced Model is the starting point for the analysis of a bifurcation phenomenon from symmetric to asymmetric domain walls. Moreover, it allows for capturing asymmetric domain walls including their extended tails (which were previously inaccessible to brute-force numerical simulation).
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A Reduced Model for domain walls in soft ferromagnetic films at the cross-over from symmetric to asymmetric wall types
J. Eur. Math. Soc. (JEMS) 6, 2014Co-Authors: Lukas Döring, Radu Ignat, Felix OttoAbstract:We study the Landau-Lifshitz Model for the energy of multi-scale transition layers -- called "domain walls" -- in soft ferromagnetic films. Domain walls separate domains of constant magnetization vectors $m^\pm \in \mathbb{S}^2$ that differ by an angle $2\alpha$. Assuming translation invariance tangential to the wall, our main result is the rigorous derivation of a Reduced Model for the energy of the optimal transition layer, which in a certain parameter regime confirms the experimental, numerical and physical predictions: The minimal energy splits into a contribution from an asymmetric, divergence-free core which performs a partial rotation in $\mathbb{S}^2$ by an angle $2\theta$, and a contribution from two symmetric, logarithmically decaying tails, each of which completes the rotation from angle $\theta$ to $\alpha$ in $\mathbb{S}^1$. The angle $\theta$ is chosen such that the total energy is minimal. The contribution from the symmetric tails is known explicitly, while the contribution from the asymmetric core is analyzed in [7]. Our Reduced Model is the starting point for the analysis of a bifurcation phenomenon from symmetric to asymmetric domain walls. Moreover, it allows for capturing asymmetric domain walls including their extended tails (which were previously inaccessible to brute-force numerical simulation).
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A Reduced Model for Simulating Grain Growth
Free Boundary Problems, 2003Co-Authors: Reiner Henseler, Barbara Niethammer, Felix OttoAbstract:We introduce a Reduced Model to study normal grain growth in two dimensions, which is based on the gradient flow structure of the mean curvature flow. In the simplified Model, we restrict this gradient flow to grain boundaries which are straight lines. We present simulations for a large number of grains and we also study the effect of anisotropies.
Andro Mikelić - One of the best experts on this subject based on the ideXlab platform.
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Blood Flow in Compliant Arteries: An Effective Viscoelastic Reduced Model, Numerics, and Experimental Validation
Annals of Biomedical Engineering, 2006Co-Authors: Sunčica Čanić, Craig J. Hartley, Doreen Rosenstrauch, Josip Tambača, Giovanna Guidoboni, Andro MikelićAbstract:The focus of this work is on Modeling blood flow in medium-to-large systemic arteries assuming cylindrical geometry, axially symmetric flow, and viscoelasticity of arterial walls. The aim was to develop a Reduced Model that would capture certain physical phenomena that have been neglected in the derivation of the standard axially symmetric one-dimensional Models, while at the same time keeping the numerical simulations fast and simple, utilizing one-dimensional algorithms. The viscous Navier–Stokes equations were used to describe the flow and the linearly viscoelastic membrane equations to Model the mechanical properties of arterial walls. Using asymptotic and homogenization theory, a novel closed, “one-and-a-half dimensional” Model was obtained. In contrast with the standard one-dimensional Model, the new Model captures: (1) the viscous dissipation of the fluid, (2) the viscoelastic nature of the blood flow – vessel wall interaction, (3) the hysteresis loop in the viscoelastic arterial walls dynamics, and (4) two-dimensional flow effects to the leading-order accuracy. A numerical solver based on the 1D-Finite Element Method was developed and the numerical simulations were compared with the ultrasound imaging and Doppler flow loop measurements. Less than 3% of difference in the velocity and less than 1% of difference in the maximum diameter was detected, showing excellent agreement between the Model and the experiment.
Karim Drifi - One of the best experts on this subject based on the ideXlab platform.
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Surface Circulation from Satellite Images: Reduced Model of the Black Sea
2013Co-Authors: Etienne Huot, Isabelle Herlin, Giuseppe Papari, Karim DrifiAbstract:Estimating surface circulation from satellite images is a hot subject for a large range of applications. Motion estimation from image data has been studied for long in the literature of Image Processing, and more recently in that of Data Assimilation (DA). This paper describes how the construction of dedicated spaces for projecting motion and image fields allows applying DA methods with a Reduced Model and eases the estimation of surface circulation on the whole Black Sea basin.
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Motion estimation on ocean satellite images by data assimilation in a wavelets Reduced Model
2013Co-Authors: Etienne Huot, Isabelle Herlin, Giuseppe Papari, Karim DrifiAbstract:This research concerns the issue of estimating surface motion from satellite images. The approach relies on a Reduced Model, obtained by Galerkin projection of dynamic equations on subspaces of velocity and image fields. The dynamics expresses the transport of image brightness and advection-diffusion of velocity. A data assimilation method is defined that assimilates image coefficients in the Reduced Model in order to estimate motion coefficients.
Vladislav Yastrebov - One of the best experts on this subject based on the ideXlab platform.
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Rough surface contact analysis by means of the Finite Element Method and of a new Reduced Model
Comptes Rendus Mécanique, 2011Co-Authors: Vladislav Yastrebov, Julian Durand, Henry Proudhon, Georges CailletaudAbstract:This article presents two approaches of a normal frictionless mechanical contact between an elastoplastic material and a rigid plane: a full scale finite element analysis (FEA) and a Reduced Model. Both of them use a representative surface element (RSE) of an experimentally measured surface roughness. The full scale FEA is performed with the Finite Element code Zset using its parallel solver. It provides the reference for the Reduced Model. The ingredients of the Reduced Model are a series of responses that are calibrated by means of FEA on a single asperity and phenomenological rules to account for asperity-asperity interaction. The Reduced Model is able to predict the load-displacement curve, the real contact area and the free volume between the contacting pair during the compression of a rough surface against a rigid plane. The CPU time is a few seconds for the Reduced Model, instead of a few days for the full FEA.
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Rough surface contact analysis by means of the Finite Element Method and of a new Reduced Model
Comptes Rendus Mécanique, 2011Co-Authors: Vladislav Yastrebov, Julian Durand, Henry Proudhon, Georges CailletaudAbstract:International audienceThis article presents two approaches of a normal frictionless mechanical contact between an elastoplastic material and a rigid plane: a full scale finite element analysis (FEA) and a Reduced Model. Both of them use a representative surface element (RSE) of an experimentally measured surface roughness. The full scale FEA is performed with the Finite Element code Zset using its parallel solver. It provides the reference for the Reduced Model. The ingredients of the Reduced Model are a series of responses that are calibrated by means of FEA on a single asperity and phenomenological rules to account for asperity-asperity interaction. The Reduced Model is able to predict the load-displacement curve, the real contact area and the free volume between the contacting pair during the compression of a rough surface against a rigid plane. The CPU time is a few seconds for the Reduced Model, instead of a few days for the full FEA
