• Title/Summary/Keyword: Non-quadratic yield function

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Prediction of Anisotropy and Formability of Lithium-ion Battery Pouch Sheet using Non-quadratic Yield Function (비이차 비등방 항복함수를 이용한 리튬-이온 배터리 파우치의 이방성 및 성형성 예측)

  • J. S. Kim;C. M. Moon;H.R. Lee;M. G. Lee
    • Transactions of Materials Processing
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    • v.32 no.3
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    • pp.136-144
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    • 2023
  • This study analyzed the mechanical behavior of lithium-ion battery pouch material and predicted its formability. A homogenization method was used to evaluate the physical properties of the pouch, and a new hardening model was developed. The yield function for the plastic model was optimized, and the anisotropic property was determined. Also, the forming limits were measured and predicted using the M-K forming limit diagram. Finally, a square cup drawing experiment confirmed the accuracy of the measured mechanical properties and the formability calculation.

Non-linear modelling to describe lactation curve in Gir crossbred cows

  • Bangar, Yogesh C.;Verma, Med Ram
    • Journal of Animal Science and Technology
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    • v.59 no.2
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    • pp.3.1-3.7
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    • 2017
  • Background: The modelling of lactation curve provides guidelines in formulating farm managerial practices in dairy cows. The aim of the present study was to determine the suitable non-linear model which most accurately fitted to lactation curves of five lactations in 134 Gir crossbred cows reared in Research-CumDevelopment Project (RCDP) on Cattle farm, MPKV (Maharashtra). Four models viz. gamma-type function, quadratic model, mixed log function and Wilmink model were fitted to each lactation separately and then compared on the basis of goodness of fit measures viz. adjusted $R^2$, root mean square error (RMSE), Akaike's Informaion Criteria (AIC) and Bayesian Information Criteria (BIC). Results: In general, highest milk yield was observed in fourth lactation whereas it was lowest in first lactation. Among the models investigated, mixed log function and gamma-type function provided best fit of the lactation curve of first and remaining lactations, respectively. Quadratic model gave least fit to lactation curve in almost all lactations. Peak yield was observed as highest and lowest in fourth and first lactation, respectively. Further, first lactation showed highest persistency but relatively higher time to achieve peak yield than other lactations. Conclusion: Lactation curve modelling using gamma-type function may be helpful to setting the management strategies at farm level, however, modelling must be optimized regularly before implementing them to enhance productivity in Gir crossbred cows.

3-D FEM Analysis of Forming Processes of Planar Anisotropic Sheet Metal (평면이방성 박판성형공정의 3차원 유한요소해석)

  • 이승열;금영탁;박진무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.8
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    • pp.2113-2122
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    • 1994
  • The 3-D FEM analysis for simulating the stamping operation of planar anisotropic sheet metals with arbitrarily-shaped tools is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The consistent full set of governing relations, comprising equilibrium equation and mesh-normal geometric constraints, is appropriately linearized. The linear triangular elements are used for depicting the formed sheet, based on membrane approximation. Barlat's non-quadratic anisotropic yield criterion(strain-rate potential) is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and non-quadratic function parameter. The planar anisotropic finite element formulation is tested with the numerical simulations of the stamping of an automotive hood inner panel and the drawing of a hemispherical punch. The in-plane anisotropic effects on the formability of both mild steel and aluminum alloy sheet metals are examined.

Approximate Yield Criterion for Voided Anisotropic Ductile Materials

  • Kim, Youngsuk;Sungyeun Won;Kim, Dogsoo;Hyunsung Son
    • Journal of Mechanical Science and Technology
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    • v.15 no.10
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    • pp.1349-1355
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    • 2001
  • As most fractures of ductile materials in metal forming processes occurred due to the results of evolution of internal damage - void nucleation, growth and coalescence. In this paper, an approximate yield criterion for voided (porous) anisotropic ductile materials is developed. The proposed approximate yield function is based on Gurson's yield function in conjunction with the Hosford's non-quadratic anisotropic yield criterion in order to consider the characteristic of anisotropic properties of matrix material. The associated flow rules are presented and the laws governing void growth with strain are derided. Using the proposed model void growth of an anisotropic sheet under biaxial tensile loading and its effect on sheet metal formability are investigated. The yield surface of voided anisotropic sheet and void growth with strain are predicted and compared with the experimental results.

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Springback Prediction of Friction Stir Welded DP590 Steel Sheet Considering Permanent Softening Behavior (영구연화거동을 고려한 마찰교반용접(FSW)된 DP590 강판의 탄성복원 예측)

  • Kim, J.;Lee, W.;Chung, K.H.;Park, T.;Kim, D.G.;Kim, Chong-Min;Kim, D.
    • Transactions of Materials Processing
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    • v.18 no.4
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    • pp.329-335
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    • 2009
  • In order to better predict the springback for friction stir welded DP590 steel sheet, the combined isotropic-kinematic hardening was formulated with considering the permanent softening behavior during reverse loading. As for yield function, the non-quadratic anisotropic yield function, Yld2000-2d, was used under plane stress condition. For the verification purposes, comparisons of simulation and experiments were performed here for the unconstrained cylindrical bending, the 2-D draw bending tests. For two applications, simulations showed good agreements with experiments.

Finite Element Analysis and Experimental Investigation of Non-isothermal Forming Processes for Aluminum-Alloy Sheet Metals (Part2:Analysis) (알루미늄 합금박판 비등온 성형공정의 유한요소 해석 및 실험적 연구 (제2부:해석))

  • 김성민;구본영;금영탁;김종호
    • Transactions of Materials Processing
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    • v.8 no.3
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    • pp.252-261
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    • 1999
  • The 3-dimensional finite element program is developed to analyze the non-isothermal forming processes of aluminum-alloy sheet metals. Bishop's method is introduced to solve the heat balance and force equilibrium equations. Also, Barlat's non-quadratic anisotropic yield function depicts the planar anisotropy of the aluminum-alloy sheet. To find an appropriate constitutive equation, four different forms are reviewed. For the verification of the reliability of the developed program, the computational try-outs of the non-isothermal cylindrical cupping processes of AL5052-H32 and Al1050-H16 are carried out. As results, the constitutive equation relating to strain and strain-rate, in which the constants are represented by the 5th-degree polynomials of temperature, is in good agreement with measurement. The computational try-outs can predict optimal forming conditions in non-isothermal forming processes.

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Time-Dependent Spring-back Prediction of Aluminum Alloy 6022-T4 Sheets Using Time-Dependent Constitutive law (시간 의존성 구성방정식을 이용한 AA6022-T4 판재의 탄성 복원 예측)

  • Park, T.;Ryou, H.;Lee, M.G.;Chung, K.H.;Wagoners, R.H.;Chung, K.
    • Transactions of Materials Processing
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    • v.18 no.6
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    • pp.494-499
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    • 2009
  • The time-dependent constitutive law was utilized based on viscoelastic-plasticity to predict the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.

Time-Dependent Spring-back Prediction of Aluminum Alloy 6022-T4 Sheets Using Time-Dependent Constitutive law (시간 의존성 구성방정식을 이용한 AA6022-T4 판재의 탄성 복원 예측)

  • Park, T.;Ryou, R.;Lee, M.G.;Chung, K.H.;Wagoner, R.H.;Chung, K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.330-333
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    • 2009
  • The time-dependent constitutive law was developed based on viscoelastic-plasticity to describe the time-dependent spring-back behavior of aluminum alloy 6022-T4 sheets. Besides nonlinear viscoelasticity, non-quadratic anisotropic yield function, Yld2000-2d, was used to account for the anisotropic yield behavior, while the combined isotropic-kinematic hardening law was used to represent the Bauschinger effect and transient hardening. For verification purposes, finite element simulations were performed for the draw-bending and the results were compared with experimental results.

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Springback prediction of friction stir welded DP590 steel sheets considering permanent softening behavior (영구 연화 거동을 고려한 마찰교반용접(FSW) 된 DP강 판재의 탄성 복원 예측)

  • Park, T.;Lee, W.;Chung, K.H.;Kim, J.H.;Kim, D.;Kim, Chong-Min;Okamoto, Kazutaka;Wagoner, R.H.;Chung, K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.304-307
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    • 2008
  • In order to evaluate the effect of permanent softening behavior on springback prediction, 2D-draw bending simulations were compared with experiments for friction stir welded DP590 steel sheets. To account fur the nonlinear hardening behavior, the combined isotropic-kinematic hardening law was utilized with and without considering the permanent softening behavior during reverse loading. Also, the non-quadratic orthotropic yield function, Yld2000-2d, was used to describe the anisotropic initial-yielding behavior of the base sheet while anisotropic properties of the weld zone were ignored for simplicity.

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Spring-back Evaluation of Automotive Sheets Based on Combined Isotropic-Kinematic Hardening Rule (Combined Isotropic-Kinematic 경화규칙에 기초한 자동차용 알루미늄합금-및 Dual-Phase 강 판재의 스프링백 예측)

  • ;;;Chongmin Kim;Michael L. Wenner
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.10a
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    • pp.144-147
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    • 2003
  • In order to evaluate spring-back behavior in automotive sheet forming processes, a panel shape idealized as a SS-rail has been investigated. After spring-back kas been predicted fer SS-rails using the finite element analysis, results has been compared with experimental measurements for three automotive sheets. To account for hardening behavior such as the Bauschinger and transient effects in addition to anisotropic behavior, the combined isotropic-kinematic hardening law based on the Chaboche type single-surface model and a recently developed non-quadratic anisotropic yield function have been utilized, respectively.

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