Faculty Profiles - UEMORI Takeshi

Papers - UEMORI Takeshi

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Effect of strain-rate and temperature on yield locus for 5083 aluminum alloy sheet Reviewed

T Naka, Y Nakayama, T Uemori, R Hino, F Yoshida

ADVANCES IN ENGINEERING PLASTICITY AND ITS APPLICATIONS, PTS 1 AND 2 274-276 937 - 942 2004

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANS TECH PUBLICATIONS LTD

To determine yield locus of type, 5083 aluminum-magnesium sheet at elevated temperature, biaxial tensile experiments were performed, using cruciform specimens, at various temperatures (25 - 300 degreesC) at strain rates raging from 10(-5) to 10(-2) s(-1). From the experimental results, the effects of strain rate and temperature on the yield locus are discussed. The size of yield locus drastically decreased with increasing temperature and with decreasing strain rate. Neither von Mises' yield criterion or Hill's can well predict the shape of yield locus of this type of sheet metal. In contrast, the yield criterion of Logan-Hosford or Barlat well simulate the yield locus at elevated temperatures.

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A model of large-strain cyclic plasticity and its application to springback simulation

F Yoshida, T Uemori

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES 45 ( 10 ) 1687 - 1702 2003.10

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

This paper presents a framework of constitutive modeling of large-strain cyclic plasticity which describes both the deformation- and texture-induced anisotropies of materials. In this model, the transient Bauschinger effect is described accurately by a new equation of the backstress evolution, and the strain-range and mean-strain dependencies of cyclic strain hardening are expressed by a model of workhardening stagnation. For the description of texture-induced anisotropy, any of widely accepted yield criteria of orthotropic anisotropy is easily incorporated into this model. This paper demonstrates the advantage of the present model in the springback analysis over other classical models by comparing the FE simulations of draw bending with the corresponding experimental results. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijmecsci.2003.10.013

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Effects of temperature on yield locus for 5083 aluminum alloy sheet

T Naka, Y Nakayama, T Uemori, R Hino, F Yoshida

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 140 494 - 499 2003.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Warm press forming of aluminum alloy sheets is quite attractive, since undesirable stretcher strain marks, which often appear on the surface of the sheets during cold press forming, will disappear at high temperature, and furthermore, some aluminum alloys exhibit high-temperature superplasticity at a certain forming speed. In order to determine the optimum condition of press forming for an aluminum alloy sheet, the effect of forming temperature on the yield locus was experimentally investigated. The yield locus for a fine-grain Al-Mg alloy (5083-O) sheet was obtained by performing biaxial tensile tests, using cruciform specimens, at temperatures of 30, 100, 170, 250 and 300 degreesC at strain rate of 10 s(-1). The size of yield locus drastically decreased with increasing temperature. Neither von Mises' criterion or Hill's can well predict the shape of the yield locus of this sheet metal. Instead of these quadratic yield functions, the yield criterion of Logan-Hosford or Barlat is a better choice for the accurate description of biaxial stress-strain responses at a high temperature. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0924-0136(03)00780-5

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Effects of temperature on yield locus for 5083 aluminum alloy sheet

T Naka, Y Nakayama, T Uemori, R Hino, F Yoshida

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 140 494 - 499 2003.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

DOI： 10.1016/S0924-0136(03)00780-5

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A model of large-strain cyclic plasticity and its application to springback simulation Reviewed

F Yoshida, T Uemori

ENGINEERING PLASTICITY FROM MACROSCALE TO NANOSCALE PTS 1 AND 2 233-2 47 - 58 2003

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANS TECH PUBLICATIONS LTD

This paper presents a framework of constitutive modeling of large-strain cyclic plasticity which describes both the deformation- and texture-induced anisotropies of materials. In this model, the transient Bauschinger effect is described accurately by a new equation of the backstress evolution, and the strain-range and mean-strain dependencies of cyclic strain-hardening are expressed by a model of workhardening stagnation. For the description of texture-induced anisotropy, any of widely accepted yield criteria of orthotropic anisotropy is easily incorporated into this model. This paper demonstrates the advantage of the present model in the springback analysis over other classical models by comparing the FE simulations of draw-bending with the corresponding experimental results.

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A Constitutive Equation for Description of Large-Strain Cyclic Plasticity

YOSHIDA Fusahito, UEMORI Takeshi

Transactions of the Japan Society of Mechanical Engineers 68 ( 667 ) 415 - 421 2002

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

This paper presents a constitutive model of plasticity that describes the cyclic stress-strain responses at large strain. A new equation of backstress evolution is proposed for an accurate simulation of the transient Bauschinger effect. An original idea of a non-isotropic-hardening surface defined in the stress space is presented for the description of the workhardening stagnation appearing under reverse deformation, as well as the strain-range and mean-strain dependencies of cyclic hardening characteristics. The validity of this model is confirmed by comparing the cyclic stress-strain responses calculated by the model with the experimental observations on two types of steel sheets (an aluminum-killed steel and a dual-phase high strength steel of 590 MPa tensile strength).

DOI： 10.1299/kikaia.68.415

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Other Link： https://jlc.jst.go.jp/DN/JALC/00155932935?from=CiNii

Importance of Appropriate Modeling of the Bauschinger Effect in Springback Analysis

Journal of the Japan Society for Technology of Plasticity 43 ( 498 ) 65 - 69 2002

Investigation of Cyclic Elasto-Plastic Behavior of Coppeer Sheet

Key Engineering Materials 2002

Elastic-plastic behavior of steel sheets under in-plane cyclic tension-compression at large strain

F Yoshida, T Uemori, K Fujiwara

INTERNATIONAL JOURNAL OF PLASTICITY 18 ( 5-6 ) 633 - 659 2002

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Elastic-plastic behavior of two types of steel sheets for press-forming (an aluminum-killed mild steel and a dual-phase high strength steel of 590 MPa ultimate tensile strength) under inplane cyclic tension-compression at large strain (up to 25% strain for mild steel and 13% for high strength steel) have been investigated. From the experiments, it was found that the cyclic hardening is strongly influenced by cyclic strain range and mean strain. Transient softening and workhardening stagnation due to the Bauschinger effect, as well as the decrease in Young's moduli with increasing prestrain, were also observed during stress reversals. Some important points in constitutive modeling for such large-strain cyclic elasto-plasticity are discussed by comparing the stress-strain responses calculated by typical constitutive models of mixed isotropic-kinematic hardening with the corresponding experimental observations. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0749-6419(01)00049-3

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スプリングバック解析におけるバウシンガー効果の適切なモデル化の重要性

塑性と加工 43 ( 498 ) 65 - 69 2002

高張力鋼板の面内応力反転時の弾塑性挙動とそのモデル化

塑性と加工 43 ( 494 ) 59 - 63 2002

A model of large-strain cyclic plasticity describing the Bauschinger effect and workhardening stagnation

F Yoshida, T Uemori

INTERNATIONAL JOURNAL OF PLASTICITY 18 ( 5-6 ) 661 - 686 2002

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

This paper presents a constitutive model that has a high capability of describing the deformation behavior of large-strain cyclic plasticity and also the stress-strain responses at small-scale re-yielding after large prestrain. A new equation of backstress evolution is proposed for an accurate simulation of the transient Bauschinger effect. Furthermore, an original idea of a non-isotropic-hardening surface defined in the stress space is presented for the description of the workhardening stagnation appearing under reverse deformation, as well as the strain-range and mean-strain dependencies of cyclic hardening characteristics. The validity of this model is confirmed by comparing the cyclic stress-strain responses calculated by the model with the experimental observations on some steel sheets and an aluminum sheet. (C) 2002 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0749-6419(01)00050-X

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Investigation of cyclic elasto-plastic behavior of copper sheet

Takeshi Uemori, Fusahito Yoshida

Key Engineering Materials 233-236 ( I ) 287 - 292 2002

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Trans Tech Publications Ltd

The cyclic plasticity behavior of an anisotropic copper sheet metal was investigated by performing in-plane tension-compression experiments. In this copper sheet, the cyclic stress amplitude of a specimen of rolling direction is apparently larger than that of the transverse direction. In order to describe such anisotropic workhardening characteristics in cyclic plasticity, as well as the Bauschinger effect, the new version of Yoshida-Uemori model, which incorporates Gotoh's quadratic yield function of the orthotropic anisotropy, was employed. The cyclic stress-strain responses calculated by this model shows in good agreement with the experimental observations.

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軟鋼板の大ひずみ繰返し塑性変形挙動とその構成モデル

塑性と加工 30 ( 338 ) 358 - 364 2001

Plasticity Models Describing the Bauschinger Effect and Yield-Point Phenomena

INZYNIERIA MATERIALOWA 974?980 2001

FE analysis of springback in hat-bending with consideration of initial anisotropy and the Bauschinger effect

T Uemori, T Okada, F Yoshida

ADVANCES IN ENGINEERING PLASTICITY, PTS 1-2 177-1 497 - 502 2000

Language：English Publishing type：Research paper (scientific journal) Publisher：TRANS TECH PUBLICATIONS LTD

This paper demonstrates how strongly the analytical prediction of springback is influenced by the description of material's stress-strain responses appearing during stress reversal. For the finite element analysis of hat-bending and the subsequent springback, three different types of constitutive models, i.e., (a) isotropic hardening (IH) model, (b) linearly kinematic hardening (LKH) model, and (c) combined hardening (IH+LKH+non-linearly kinematic hardening [NLKH]) model, were employed. When using the combined hardening model, the calculated sheet geometries showed the excellent agreement with the experimental results, while the predictions by both the IH and LKH models underestimate the springback.

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Simulation of springback in V-bending process by elasto-plastic finite element method with consideration of Bauschinger effect

T Uemori, T Okada, F Yoshida

METALS AND MATERIALS-KOREA 4 ( 3 ) 311 - 314 1998

Language：English Publishing type：Research paper (scientific journal) Publisher：KOREAN INST METALS MATERIALS

This paper presents the prediction of springback in sheet metal forming in terms of the description of the Bauschinger effect. It addresses three different types of constitutive models: an iso-tropic hardening model (IH model), a linearly kinematic hardening model (LK model), and a model of combined linearly-nonlinearly kinematic and isotropic hardening (L-NK+IH model). The springback predicted by the L-NK+IH model is found to be more pronounced than that by the III and the LK model. It is caused by the stress-strain response characterized by the gradual transition from fully elastic to plastic behavior during stress-reversal, which is essential to the L-NK+IH model.

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Prediction of active slip system for commercially pure titanium sheet by crystal plasticity finite element analysis

Takeshi UEMORI, Naoya TADA, Junji SAKAMOTO, Masatoshi DOI

Extended abstract of The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023 (ATEM-iDICs '23) 19-G05 1900

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