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Nobutada Ohno - One of the best experts on this subject based on the ideXlab platform.
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homogenized elastic Viscoplastic Behavior of plate fin structures with two pore pressures
International Journal of Mechanical Sciences, 2014Co-Authors: Nobutada Ohno, Kohei Narita, Dai OkumuraAbstract:Abstract We investigate the homogenized elastic–Viscoplastic Behavior of plate-fin structures subjected to two pore pressures, p 1 and p 2 . The plate-fin structures considered are assumed to be periodic and composed of metallic materials. Hill's macrohomogeneity equation is used to show three special cases in which one of p 1 , p 2 or p m (the mean of p 1 and p 2 ) entirely affects the homogenized Viscoplastic Behavior in the steady state. To verify the three special cases, we perform FEH (finite element homogenization) analysis of an ultrafine plate-fin structure subjected to p 1 and p 2 , for which two base metals with different strain-rate sensitivities are considered. It is demonstrated that the three special cases typically occur under uniaxial tension and compression in the stacking direction, depending on the strain-rate sensitivity of the base metals. It is further shown that a macromaterial model reproduces well the homogenized stress–strain relations attained in the FEH analysis if p 1 , p 2 or p m is entered for Terzaghi׳s effective stress in the Viscoplastic equation in the macromaterial model.
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Homogenized elastic–Viscoplastic Behavior of plate-fin structures with two pore pressures
International Journal of Mechanical Sciences, 2014Co-Authors: Nobutada Ohno, Kohei Narita, Dai OkumuraAbstract:Abstract We investigate the homogenized elastic–Viscoplastic Behavior of plate-fin structures subjected to two pore pressures, p 1 and p 2 . The plate-fin structures considered are assumed to be periodic and composed of metallic materials. Hill's macrohomogeneity equation is used to show three special cases in which one of p 1 , p 2 or p m (the mean of p 1 and p 2 ) entirely affects the homogenized Viscoplastic Behavior in the steady state. To verify the three special cases, we perform FEH (finite element homogenization) analysis of an ultrafine plate-fin structure subjected to p 1 and p 2 , for which two base metals with different strain-rate sensitivities are considered. It is demonstrated that the three special cases typically occur under uniaxial tension and compression in the stacking direction, depending on the strain-rate sensitivity of the base metals. It is further shown that a macromaterial model reproduces well the homogenized stress–strain relations attained in the FEH analysis if p 1 , p 2 or p m is entered for Terzaghi׳s effective stress in the Viscoplastic equation in the macromaterial model.
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homogenized elastic Viscoplastic Behavior of thick perforated plates with pore pressure
Key Engineering Materials, 2013Co-Authors: Kazutaka Ikenoya, Noriko Takano, Nobutada Ohno, Naoto KasaharaAbstract:The homogenized elastic-Viscoplastic Behavior of thick perforated plates with pore pressure is investigated for macro-material modeling. To this end, the homogenized Behavior is analyzed using a FE homogenization method of periodic solids. It is assumed that the base metal of perforated plates exhibits the elastic-Viscoplastic Behavior based on Hooke’s law and Norton’s power-law. The resulting homogenized Behavior is simulated using an elastic-Viscoplastic macro-material model developed for pore-pressurized anisotropic open-porous bodies. It is shown that the macro-material model suitably represents the macro-anisotropy and macro-volumetric compressibility that are revealed by the FE homogenization analysis in the presence and absence of pore pressure.
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Homogenized Elastic-Viscoplastic Behavior of Anisotropic Open-Porous Bodies
Key Engineering Materials, 2013Co-Authors: Nobutada OhnoAbstract:This lecture presents constitutive modeling of the homogenized elastic-Viscoplastic Behavior of pore-pressurized anisotropic open-porous bodies. The base solids are assumed to be metallic materials at small strains and rotations. First, by describing micro-macro relations relevant to periodic unit cells of anisotropic open-porous bodies with pore pressure, constitutive features are discussed for the Viscoplastic macrostrain rate in steady states. Second, on the basis of the constitutive features found, the Viscoplastic macrostrain rate is represented as an anisotropic function of Terzaghi’s effective stress. Third, the resulting Viscoplastic equation is used to simulate the homogenized elastic-Viscoplastic Behavior of an ultrafine plate-fin structure and a thick perforated plate subjected to macroscopic loading in the absence and presence of pore pressure. The corresponding FE homogenization analysis is performed for comparison to validate the developed Viscoplastic equation.
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Homogenized Elastic-Viscoplastic Behavior of Thick Perforated Plates with Pore Pressure
Key Engineering Materials, 2013Co-Authors: Kazutaka Ikenoya, Noriko Takano, Nobutada Ohno, Naoto KasaharaAbstract:The homogenized elastic-Viscoplastic Behavior of thick perforated plates with pore pressure is investigated for macro-material modeling. To this end, homogenized stress-strain relations of a periodic unit cell of pore-pressurized thick perforated plates under uniaxial and multiaxial loadings are analyzed using a finite element method with periodic boundary conditions. It is assumed in the analysis that the base metal of the perforated plates exhibits elastic-Viscoplasticity based on Hooke’s law and Norton’s power law and has the material parameters of Mod. 9Cr-1Mo steel at 550 \(^\circ \)C. The resulting homogenized stress-strain relations are simulated using a macro-material model in which the pore-Viscoplastic macro-strain rate is represented as an anisotropic power function of Terzaghi’s effective stress. It is demonstrated that this macro-material model suitably represents the macro-anisotropy, macro-volumetric compressibility, and pore pressure effect revealed in the Viscoplastic range in the finite element homogenization analysis.
Tetsuya Matsuda - One of the best experts on this subject based on the ideXlab platform.
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A novel basic cell modeling method for elastic-Viscoplastic homogenization analysis of plain-woven laminates with nesting
International Journal of Mechanical Sciences, 2018Co-Authors: Gai Kubo, Tetsuya Matsuda, Yoshihiko SatoAbstract:Abstract In this study, a novel basic cell modeling method is developed for the elastic-Viscoplastic homogenization analysis of plain-woven laminates with nesting. For this, based on the periodicity and point-symmetry of internal structures of plain-woven laminates with nesting, a hexagonal prism-shaped basic cell and its boundary conditions are proposed. The basic cell and boundary conditions are then introduced into the homogenization theory for nonlinear time-dependent composites developed by the authors. Using the present method, elastic-Viscoplastic Behavior of a plain-woven glass fiber-reinforced plastic (GFRP) laminate with nesting subjected to on- and off-axis loading is analyzed. In the analysis, the present method is successful in significantly reducing the analysis domain, and in achieving the modeling of a high volume fraction of fiber bundles. It is shown from the analysis results that the present method accurately predicts experimentally observed macroscopic elastic-Viscoplastic Behavior of the plain-woven GFRP laminate with nesting. In addition, the elastic-Viscoplastic analysis of plain-woven GFRP laminates without nesting is also conducted, showing that the nesting affects elastic-Viscoplastic Behavior of plain-woven GFRP laminates.
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Elasto-Viscoplastic Analysis of Slanting-Weft Woven Fabric Composites Based on Homogenization Theory
Key Engineering Materials, 2016Co-Authors: Keita Goto, Takuya Tomioka, Masahiro Arai, Tetsuya MatsudaAbstract:The elasto-Viscoplastic Behavior of slanting-weft woven laminates, the fiber bundles of which are not crossed at a right angle, is investigated both macroscopically and microscopically. For this, an analysis model for the [±θ] slanting-weft woven laminate with a cross angle ±θ and its diamond-shaped unit cell are considered. Then, a basic cell, which is quarter of the unit cell, is defined as an analysis domain by considering the point-symmetry of the internal structure. For the basic cell, the homogenization theory for nonlinear time-dependent composites with point-symmetric internal structures is applied. Using the present method, the elasto-Viscoplastic analysis of the [±θ] slanting-weft woven laminates subjected to an in-plane uniaxial tensile load is performed. From the analysis results, the macroscopic elasto-Viscoplastic Behavior and the microscopic stress and strain distributions of the laminates are investigated.
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Fully-Modeled Unit Cell Analysis for Macro/Micro Elastic-Viscoplastic Behavior of Quasi-Isotropic CFRP Laminates
Key Engineering Materials, 2014Co-Authors: Keita Goto, Tetsuya Matsuda, Naoto KubotaAbstract:A fully-modeled unit cell analysis is performed to investigate the macroscopic and microscopic elastic-Viscoplastic Behaviors of a quasi-isotropic carbon fiber-reinforced plastic (CFRP) laminate. To this end, a quasi-isotropic CFRP laminate and its microstructure composed of carbon fibers and a matrix material are considered three-dimensionally. Then, a hexagonal prism-shaped unit cell fully modeled with fibers and a matrix including interlaminar areas is defined. For this quasi-isotropic laminate, a homogenization theory for nonlinear time-dependent composites with point-symmetric internal structures is applied, enabling us to analyze both the macroscopic and microscopic elastic-Viscoplastic Behaviors of the laminate. The substructure method is introduced into the theory to reduce computational costs. The present method is then applied to the elastic-Viscoplastic analysis of a quasi-isotropic carbon fiber/epoxy laminate subjected to an in-plane uniaxial tensile load, to investigate the macroscopic elastic-Viscoplastic Behavior of the laminate and the microscopic stress and strain distributions in them.
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Analysis of Elastic-Viscoplastic Behavior of Honeycomb Sandwich Panels Based on a Homogenization Theory for Free Edge Analysis
Key Engineering Materials, 2013Co-Authors: Takayuki Koda, Tetsuya MatsudaAbstract:In this study, the elastic-Viscoplastic properties of aluminum honeycomb sandwich panels are investigated using a homogenization theory for free edge analysis. For this, the mathematical homogenization theory is reconstructed for elastic-Viscoplastic analysis of honeycomb sandwich panels by introducing a traction free boundary condition. Moreover, the domain of analysis is reduced to a quarter using point-symmetry of internal structures of honeycomb sandwich panels. The present method is then applied to the analysis of macroscopic elastic-Viscoplastic Behavior and microscopic stress distribution of an aluminum honeycomb sandwich panel subjected to in-plane uniaxial compression. It is shown that the stress concentration arises at face/core interfaces, especially at intersections of core walls.
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homogenized elastic Viscoplastic Behavior of anisotropic open porous bodies with pore pressure
International Journal of Solids and Structures, 2012Co-Authors: Nobutada Ohno, Kazutaka Ikenoya, Dai Okumura, Tetsuya MatsudaAbstract:Abstract Constitutive modeling is studied for the homogenized elastic–Viscoplastic Behavior of pore-pressurized anisotropic open-porous bodies made of metallic base solids at small strains and rotations. For this purpose, by describing micro–macro relations relevant to periodic unit cells of anisotropic open-porous bodies subjected to pore pressure, constitutive features are discussed for the Viscoplastic macrostrain rate in steady states. On the basis of the constitutive features found, the Viscoplastic macrostrain rate is represented as an anisotropic function of Terzaghi’s effective stress, which is shown using Hill’s macrohomogeneity condition. The resulting Viscoplastic equation is used to simulate the homogenized elastic–Viscoplastic Behavior of an ultrafine plate-fin structure subjected to uniaxial/biaxial loading in addition to pore pressure. The corresponding finite element homogenization analysis is also performed for comparison. It is demonstrated that the developed Viscoplastic equation simulates well the anisotropic effect of pore pressure in the Viscoplastic range in spite of there being no anisotropic factor and no fitting parameter in Terzaghi’s effective stress itself.
Masataka Tokuda - One of the best experts on this subject based on the ideXlab platform.
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elastic Viscoplastic Behavior of plain woven gfrp laminates homogenization using a reduced domain of analysis
Composite Structures, 2007Co-Authors: Tetsuya Matsuda, Nobutada Ohno, Y. Nimiya, Masataka TokudaAbstract:Abstract In this study, a method for reducing the domain of analysis is developed for the homogenization analysis of plain-woven laminates. To this end, it is first shown that the internal structures of plain-woven laminates satisfy point-symmetry on the assumption that the laminates have the in-phase or out-of-phase laminate configuration of plain fabrics. The point-symmetry is then utilized for the boundary condition of unit cell problems, reducing the domain of analysis to 1/4 and 1/8 for the in-phase and out-of-phase laminate configurations, respectively. Using the present method, the in-plane elastic–Viscoplastic deformation of plain-woven GFRP laminates is analyzed based on the homogenization theory of nonlinear time-dependent composites. Moreover, the in-plane uniaxial tensile tests of a plain-woven GFRP laminate at a constant strain rate are performed at a room temperature. It is thus shown that the present analysis successfully predicts the in-plane elastic–Viscoplastic Behavior of plain-woven GFRP laminates. It is also shown that the laminate configurations of plain fabrics exert an influence on the Viscoplastic Behavior of laminates, not their elastic Behavior.
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Elastic–Viscoplastic Behavior of plain-woven GFRP laminates: Homogenization using a reduced domain of analysis
Composite Structures, 2007Co-Authors: Tetsuya Matsuda, Nobutada Ohno, Y. Nimiya, Masataka TokudaAbstract:Abstract In this study, a method for reducing the domain of analysis is developed for the homogenization analysis of plain-woven laminates. To this end, it is first shown that the internal structures of plain-woven laminates satisfy point-symmetry on the assumption that the laminates have the in-phase or out-of-phase laminate configuration of plain fabrics. The point-symmetry is then utilized for the boundary condition of unit cell problems, reducing the domain of analysis to 1/4 and 1/8 for the in-phase and out-of-phase laminate configurations, respectively. Using the present method, the in-plane elastic–Viscoplastic deformation of plain-woven GFRP laminates is analyzed based on the homogenization theory of nonlinear time-dependent composites. Moreover, the in-plane uniaxial tensile tests of a plain-woven GFRP laminate at a constant strain rate are performed at a room temperature. It is thus shown that the present analysis successfully predicts the in-plane elastic–Viscoplastic Behavior of plain-woven GFRP laminates. It is also shown that the laminate configurations of plain fabrics exert an influence on the Viscoplastic Behavior of laminates, not their elastic Behavior.
Masatoshi Tsuda - One of the best experts on this subject based on the ideXlab platform.
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duplex model for homogenized elastic Viscoplastic Behavior of plate fin structures at high temperatures
International Journal of Plasticity, 2011Co-Authors: Masatoshi Tsuda, Nobutada OhnoAbstract:Abstract In this study, a duplex model is developed as a constitutive model for the homogenized elastic–Viscoplastic Behavior of a class of plate–fin structures operating at high temperatures. This model consists of plate and fin layers, which are individually ruled by different macro-constitutive models. An anisotropic, compressible power-law equation that was derived in a recent study by the present authors is used to describe the homogenized Viscoplastic Behavior of the fin layer. On the other hand, an isotropic, incompressible power-law equation is used as the macro-constitutive equation of the plate layer. The duplex model developed is applied to an ultra-fine plate–fin structure made of Hastelloy X. It is shown that the duplex model is more successful under multiaxial loading than the corresponding simplex model in which plates and fins are non-separately homogenized.
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Duplex model for homogenized elastic–Viscoplastic Behavior of plate–fin structures at high temperatures
International Journal of Plasticity, 2011Co-Authors: Masatoshi Tsuda, Nobutada OhnoAbstract:Abstract In this study, a duplex model is developed as a constitutive model for the homogenized elastic–Viscoplastic Behavior of a class of plate–fin structures operating at high temperatures. This model consists of plate and fin layers, which are individually ruled by different macro-constitutive models. An anisotropic, compressible power-law equation that was derived in a recent study by the present authors is used to describe the homogenized Viscoplastic Behavior of the fin layer. On the other hand, an isotropic, incompressible power-law equation is used as the macro-constitutive equation of the plate layer. The duplex model developed is applied to an ultra-fine plate–fin structure made of Hastelloy X. It is shown that the duplex model is more successful under multiaxial loading than the corresponding simplex model in which plates and fins are non-separately homogenized.
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homogenized elastic Viscoplastic Behavior of plate fin structures at high temperatures numerical analysis and macroscopic constitutive modeling
International Journal of Mechanical Sciences, 2010Co-Authors: Masatoshi Tsuda, Nobutada Ohno, T. Asada, Eri Takemura, T. IgariAbstract:Abstract In this study, homogenized elastic–Viscoplastic Behavior of an ultra-fine plate-fin structure fabricated for compact heat exchangers is investigated. First, the homogenized Behavior is numerically analyzed using a fully implicit mathematical homogenization scheme of periodic elastic–inelastic solids. A power-law creep relation is assumed to represent the Viscoplasticity of base metals at high temperatures. The plate-fin structure is thus shown to exhibit significant anisotropy as well as noticeable compressibility in both the elastic and Viscoplastic ranges of the homogenized Behavior. Second, a non-linear rate-dependent macroscopic constitutive model is developed using the quadratic yield function proposed for anisotropic compressible plasticity. The resulting constitutive model is shown to be successful for simulating the anisotropy, compressibility, and rate dependency in the homogenized Behavior in multi-axial stress states.
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Homogenized elastic–Viscoplastic Behavior of plate-fin structures at high temperatures: Numerical analysis and macroscopic constitutive modeling
International Journal of Mechanical Sciences, 2010Co-Authors: Masatoshi Tsuda, Nobutada Ohno, T. Asada, Eri Takemura, T. IgariAbstract:Abstract In this study, homogenized elastic–Viscoplastic Behavior of an ultra-fine plate-fin structure fabricated for compact heat exchangers is investigated. First, the homogenized Behavior is numerically analyzed using a fully implicit mathematical homogenization scheme of periodic elastic–inelastic solids. A power-law creep relation is assumed to represent the Viscoplasticity of base metals at high temperatures. The plate-fin structure is thus shown to exhibit significant anisotropy as well as noticeable compressibility in both the elastic and Viscoplastic ranges of the homogenized Behavior. Second, a non-linear rate-dependent macroscopic constitutive model is developed using the quadratic yield function proposed for anisotropic compressible plasticity. The resulting constitutive model is shown to be successful for simulating the anisotropy, compressibility, and rate dependency in the homogenized Behavior in multi-axial stress states.
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Homogenized elastic-Viscoplastic Behavior of plate-fin structures at high temperatures
2009Co-Authors: Masatoshi Tsuda, T. Asada, N. Ohno, T. IgariAbstract:Summary In this study, homogenized elastic-Viscoplastic Behavior of plate-fin structures fabricated for compact heat exchangers is investigated. First, the homogenized Behavioris numerically analyzed using a fully implicit mathematical homogenization scheme of periodicelastic-inelasticsolids. A power-law creep equation is assumed to represent the Viscoplasticity of base metals at high temperatures. The plate-fin structures are thus shown to exhibit significant anisotropy as well as compressibility in both the elastic and Viscoplastic ranges of the homogenized Behavior. Second, a non-linear rate-dependent macroscopic constitutive model is developed by utilizing the quadratic yield function proposed for anisotropic compressible plasticity. The resulting constitutivemodel is shown to be successful for simulatingthe anisotropy, compressibility and rate-dependency in the homogenized Behavior in multiaxial stress states.
Richard Bernier - One of the best experts on this subject based on the ideXlab platform.
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Thermo-Viscoplastic Behavior of 304 austenitic stainless steel at various strain rates and temperatures: Testing, modeling and validation
International Journal of Mechanical Sciences, 2020Co-Authors: Alexis Rusinek, Raphaël Pesci, Slim Bahi, Richard BernierAbstract:This paper presents a systematic study of the thermo-Viscoplastic Behavior of a 304 austenitic stainless steel (ASS). The experiments were conducted over a wide range of strain rates (10 − 3 s − 1 to 3270 s − 1 ) and temperatures (-163°C to 172°C), for which the deformation Behavior of 304 ASS becomes more complex due to the strain- induced martensitic transformation (SIMT) effect. Dynamic tests at low/elevated temperatures were conducted using the Hopkinson technique coupled with a cooling device/heating furnace, and temperature distribution within the specimen was verified to be uniform. Experimental results showed that the strain hardening rate of 304 ASS was strongly affected by SIMT effect. For quasi-static tests (10 − 3 s − 1 to 1 s − 1 ) at low temperatures (-163°C to -20°C), the stress-strain relations exhibited an S-shape and a second strain hardening phenomenon. The strain rate sensitivity and temperature sensitivity of 304 ASS were also different from metallic materials deformed by dislocation glide. Several unexpected phenomena including the negative strain rate sensitivity and the changing temperature sensitivity from quasi-static to dynamic tests were observed. Based on experimental results, an extension of the Rusinek-Klepaczko (RK) model considering SIMT effect was used to simulate the deformation Behavior of 304 ASS: it predicted flow stress curves of 304 ASS above -60°C correctly. In addition, to validate the extended RK model and the identified model parameters, numerical simulations of ballistic impact tests of 304 ASS plates at various temperatures were carried out, showing a good agreement with experiments.
