The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Tayfun E. Tezduyar - One of the best experts on this subject based on the ideXlab platform.
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Finite Element Computation and experimental validation of sloshing in rectangular tanks
Computational Mechanics, 2013Co-Authors: Marcela A. Cruchaga, Ricardo S. Reinoso, Mario A. Storti, Diego J. Celentano, Tayfun E. TezduyarAbstract:Finite Element Computation and experimental validation of sloshing in rectangular tanks near the primary and secondary resonance modes are presented. In particular, 2D free-surface evolution is studied. The Computational analysis is based on solving the Navier-Stokes equations of incompressible flows with a monolithic solver that includes a stabilized formulation and a Lagrangian tracking technique for updating the free surface. The time-dependent behavior of the numerical and experimental wave heights at different control points are compared, where the experimental data is collected using ultrasonic sensors and a shake table that controls the motion of the rectangular container.
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space time supg Finite Element Computation of shallow water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space---Time and the Streamline-Upwind/Petrov---Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.
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Space–time SUPG Finite Element Computation of shallow-water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space–Time and the Streamline-Upwind/Petrov–Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.
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stabilized Finite Element Computation of nox emission in aero engine combustors
International Journal for Numerical Methods in Fluids, 2011Co-Authors: Alessandro Corsini, Franco Rispoli, Tayfun E. TezduyarAbstract:A stabilized Finite Element formulation for the Computation of turbulent reacting flows and NOx emission is presented. The method is based on the Streamline-Upwind/Petrov–Galerkin (SUPG) and Pressure-Stabilizing/Petrov-Galerkin (PSPG) formulations, complemented with directionally formulated diffusion for reaction-dominated flows (‘DRDJ’ stabilization). The stabilized formulation is applied to the advection–diffusion–reaction equations governing the turbulent combustion and the NOx emission equations based on the thermal and the N2O pathways. The simulation is carried out for a co-axial burner, with a non-premixed swirling flame. The burner is operated at high pressure to represent the take-off conditions for an aero-engine. The vortical patterns of the swirling flame are analyzed together with the temperature field and flame position. The NOx formation processes are discussed, providing insight into the features of thermal and N2O mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.
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space time Finite Element Computation of complex fluid structure interactions
International Journal for Numerical Methods in Fluids, 2010Co-Authors: Tayfun E. Tezduyar, Kenji Takizawa, Creighton Moorman, Samuel Wright, Jason D ChristopherAbstract:New special fluid-structure interaction (FSI) techniques, supplementing the ones developed earlier, are employed with the Stabilized Space-Time FSI (SSTFSI) technique. The new special techniques include improved ways of calculating the equivalent fabric porosity in Homogenized Modeling of Geometric Porosity (HMGP), improved ways of building a starting point in FSI Computations, ways of accounting for fluid forces acting on structural components that are not expected to influence the flow, adaptive HMGP, and multiscale sequentially coupled FSI techniques. While FSI modeling of complex parachutes was the motivation behind developing some of these techniques, they are also applicable to other classes of complex FSI problems. We also present new ideas to increase the scope of our FSI and CFD techniques. .
Shinsuke Takase - One of the best experts on this subject based on the ideXlab platform.
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space time supg Finite Element Computation of shallow water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space---Time and the Streamline-Upwind/Petrov---Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.
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Space–time SUPG Finite Element Computation of shallow-water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space–Time and the Streamline-Upwind/Petrov–Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.
Sofiane Guessasma - One of the best experts on this subject based on the ideXlab platform.
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Significance of pore percolation to drive anisotropic effects of 3D printed polymers revealed with X-ray ��-tomography and Finite Element Computation
Polymer, 2017Co-Authors: Sofiane Guessasma, Sofiane Belhabib, Hedi NouriAbstract:The role of porosity in 3D printed Acrylonitrile Butadiene Styrene (ABS) is studied. Dense samples are printed using fused deposition modelling with different orientations. X-ray m-tomography is used to reveal the 3D microstructures of the printed samples. Image analysis is applied to derive porosity content , connectivity and size distribution. Mechanical analysis is performed by converting 3D acquired images into Finite Element models. Simulation of uniaxial loading is carried out to predict the anisotropy induced by the printing process. Engineering constants including Poisson's coefficients and Young's moduli are derived. The results show that the low porosity content contrasts with high pore connectivity. Finite Element Computation reveals a slight transverse isotropy and weak sensitivity of the engineering constants with respect to sampling performed in both building and lateral directions. Comparison with experimental results indicates matching for Poisson's coefficients and higher sensitivity to printing orientation for Young's moduli. Sources of mismatching are attributed to interfacial effects where lack of inter-filament bonding is found to drive significantly filament decohesion perpendicular to the compression direction.
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Local mechanical behavior mapping of a biopolymer blend using nanoindentation, Finite Element Computation, and simplex optimization strategy
Journal of Applied Polymer Science, 2017Co-Authors: Sofiane Guessasma, Weihong Zhang, Jihong ZhuAbstract:In this study, we suggest a simple scheme to derive interfacial behavior using combination of nanoindentation and Finite Element Computation. The starting point is the experimental generation of a rectangular grid composed of 32 indentations to measure the exact variation of stiffness across the interface of a bio-based composite. A Finite Element simulation of nanoindentation is implemented based on elasto-plastic material model. An optimization strategy is used to identify the behavior of all phases by matching predicted results to observed mechanical response. Results show that extent of interphase layer has a typical dimension of 8.06 +/- 4.9 mm. The optimization strategy based on simplex proves to be efficient to derive the elasto-plastic behavior of the blend across the interface with a residual value of less than 30 mu N. The identification procedure demonstrates that the extent of the interfacial region depends on the measured physical quantity. The contrast across the interface for both Young's and the tangent moduli appear to be more effective than the contrast given by the yield stress. Identified Young's moduli for zein, starch, and interfacial zone are 4.78 +/- 0.27, 4.13 +/- 0.19, and 3.91 +/- 0.17 GPa. Plasticity parameter represented by tangent modulus varies in the same order as 1238 +/- 120, 847 +/- 108, and 976 +/- 94 MPa, respectively. VC 2017 Wiley Periodicals, Inc.
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determination of orthotropic properties of glass fibre reinforced thermoplastics using x ray tomography and multiscale Finite Element Computation
Composite Structures, 2016Co-Authors: Abderrahmane Ayadi, Hedi Nouri, Sofiane Guessasma, Frédéric RogerAbstract:Abstract We report a new approach to measure orthotropic properties of short glass fibre reinforced thermoplastics at the macroscopic scale taking into account all microstructural details. 3D imaging technique based on X-ray micro-tomography is used to assess fibrous architecture of an injected part at different positions characterised by different fibre flow histories. Finite Element Computation is used as a multiscale process, firstly by computing orthotropic parameters at a micro-scale for hundreds of bi-phasic 3D domains composing the macrostructure of the composite at all studied positions. Results are implemented in a second Finite Element Computation as a collection of orthotropic material models composing the heterogeneous structure of the composite.
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Determination of orthotropic properties of glass fibre reinforced thermoplastics using X-ray tomography and multiscale Finite Element Computation
Composite Structures, 2016Co-Authors: Abderrahmane Ayadi, Hedi Nouri, Sofiane Guessasma, Frédéric RogerAbstract:We report a new approach to measure orthotropic properties of short glass fibre reinforced thermoplastics at the macroscopic scale taking into account all microstructural details. 3D imaging technique based on X-ray micro-tomography is used to assess fibrous architecture of an injected part at different positions characterised by different fibre flow histories. Finite Element Computation is used as a multiscale process, firstly by computing orthotropic parameters at a micro-scale for hundreds of bi-phasic 3D domains composing the macrostructure of the composite at all studied positions. Results are implemented in a second Finite Element Computation as a collection of orthotropic material models composing the heterogeneous structure of the composite. (C) 2015 Elsevier Ltd. All rights reserved.
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Comprehensive study of biopolymer foam compression up to densification using X-ray micro-tomography and Finite Element Computation
European Polymer Journal, 2016Co-Authors: Sofiane Guessasma, Hedi NouriAbstract:The aim of this study is to understand the microstructural changes occurring during severe compression of a biopolymeric foam. In-situ airy microstructure evolution is monitored as function of loading using X-ray micro-tomography. Cell shrinkage and cell wall thickening are quantified using image analysis. Cell connectivity, morphology and size distributions are related to structural anisotropy generated by loading. Finite Element Computation is attempted to derive the mechanical model representing the compressive response up to densification. Three models are tested, namely unit cell with elasto-plastic constitutive law, Ogden hyperelasticity and an effective elasto-plastic model. The effective elastoplastic model is the most realistic model to capture compressive behaviour of the studied foam under all drying situations. Thanks to a densification stiffening term added to account for an evolving cell contact, the effective model' shows superior capabilities to capture severe compression of the bio-based foam under all drying conditions.
Hedi Nouri - One of the best experts on this subject based on the ideXlab platform.
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Significance of pore percolation to drive anisotropic effects of 3D printed polymers revealed with X-ray ��-tomography and Finite Element Computation
Polymer, 2017Co-Authors: Sofiane Guessasma, Sofiane Belhabib, Hedi NouriAbstract:The role of porosity in 3D printed Acrylonitrile Butadiene Styrene (ABS) is studied. Dense samples are printed using fused deposition modelling with different orientations. X-ray m-tomography is used to reveal the 3D microstructures of the printed samples. Image analysis is applied to derive porosity content , connectivity and size distribution. Mechanical analysis is performed by converting 3D acquired images into Finite Element models. Simulation of uniaxial loading is carried out to predict the anisotropy induced by the printing process. Engineering constants including Poisson's coefficients and Young's moduli are derived. The results show that the low porosity content contrasts with high pore connectivity. Finite Element Computation reveals a slight transverse isotropy and weak sensitivity of the engineering constants with respect to sampling performed in both building and lateral directions. Comparison with experimental results indicates matching for Poisson's coefficients and higher sensitivity to printing orientation for Young's moduli. Sources of mismatching are attributed to interfacial effects where lack of inter-filament bonding is found to drive significantly filament decohesion perpendicular to the compression direction.
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determination of orthotropic properties of glass fibre reinforced thermoplastics using x ray tomography and multiscale Finite Element Computation
Composite Structures, 2016Co-Authors: Abderrahmane Ayadi, Hedi Nouri, Sofiane Guessasma, Frédéric RogerAbstract:Abstract We report a new approach to measure orthotropic properties of short glass fibre reinforced thermoplastics at the macroscopic scale taking into account all microstructural details. 3D imaging technique based on X-ray micro-tomography is used to assess fibrous architecture of an injected part at different positions characterised by different fibre flow histories. Finite Element Computation is used as a multiscale process, firstly by computing orthotropic parameters at a micro-scale for hundreds of bi-phasic 3D domains composing the macrostructure of the composite at all studied positions. Results are implemented in a second Finite Element Computation as a collection of orthotropic material models composing the heterogeneous structure of the composite.
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Determination of orthotropic properties of glass fibre reinforced thermoplastics using X-ray tomography and multiscale Finite Element Computation
Composite Structures, 2016Co-Authors: Abderrahmane Ayadi, Hedi Nouri, Sofiane Guessasma, Frédéric RogerAbstract:We report a new approach to measure orthotropic properties of short glass fibre reinforced thermoplastics at the macroscopic scale taking into account all microstructural details. 3D imaging technique based on X-ray micro-tomography is used to assess fibrous architecture of an injected part at different positions characterised by different fibre flow histories. Finite Element Computation is used as a multiscale process, firstly by computing orthotropic parameters at a micro-scale for hundreds of bi-phasic 3D domains composing the macrostructure of the composite at all studied positions. Results are implemented in a second Finite Element Computation as a collection of orthotropic material models composing the heterogeneous structure of the composite. (C) 2015 Elsevier Ltd. All rights reserved.
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Comprehensive study of biopolymer foam compression up to densification using X-ray micro-tomography and Finite Element Computation
European Polymer Journal, 2016Co-Authors: Sofiane Guessasma, Hedi NouriAbstract:The aim of this study is to understand the microstructural changes occurring during severe compression of a biopolymeric foam. In-situ airy microstructure evolution is monitored as function of loading using X-ray micro-tomography. Cell shrinkage and cell wall thickening are quantified using image analysis. Cell connectivity, morphology and size distributions are related to structural anisotropy generated by loading. Finite Element Computation is attempted to derive the mechanical model representing the compressive response up to densification. Three models are tested, namely unit cell with elasto-plastic constitutive law, Ogden hyperelasticity and an effective elasto-plastic model. The effective elastoplastic model is the most realistic model to capture compressive behaviour of the studied foam under all drying situations. Thanks to a densification stiffening term added to account for an evolving cell contact, the effective model' shows superior capabilities to capture severe compression of the bio-based foam under all drying conditions.
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an original approach to assess elastic properties of a short glass fibre reinforced thermoplastic combining x ray tomography and Finite Element Computation
Composite Structures, 2015Co-Authors: Abderrahmane Ayadi, Hedi Nouri, Sofiane Guessasma, Frédéric RogerAbstract:Abstract A large debate animates the community about the mechanical performance of complex parts obtained by injection moulding (IM) of short glass fibre reinforced polymer (SGFRP) composites. Difficulties to measure exact fibre length and orientation distributions in complex geometries are limiting in terms of basic understanding of damage mechanisms in industrial parts and fatigue design improvement. In this work, we are interested to shed more light on the mechanical performance of short glass fibre reinforced polyamide composites in correlation to local microstructural heterogeneities which are caused by inserts used during IM. For such purpose, we combine X-ray microtomography (μ-CT) and Finite Element Computation to determine the elastic modulus in various positions in an open hole plate configuration with a dissymmetric fibre distribution. Our predictions show that effective properties do not vary significantly around the hole in all space directions. However, stress profiles (through the thickness) far enough from the hole reveal a five-layer quasi symmetric structure evolving to three-layer near the cylindrical insert. We believe that such alteration is responsible for the observed failure of the composite at precisely the positions of highly affected fibre distribution.
Seizo Tanaka - One of the best experts on this subject based on the ideXlab platform.
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space time supg Finite Element Computation of shallow water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space---Time and the Streamline-Upwind/Petrov---Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.
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Space–time SUPG Finite Element Computation of shallow-water flows with moving shorelines
Computational Mechanics, 2011Co-Authors: Shinsuke Takase, Kazuo Kashiyama, Seizo Tanaka, Tayfun E. TezduyarAbstract:We show that combination of the Deforming-Spatial-Domain/Stabilized Space–Time and the Streamline-Upwind/Petrov–Galerkin formulations can be used quite effectively for Computation of shallow-water flows with moving shorelines. The combined formulation is supplemented with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test Computations and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes.