• Title/Summary/Keyword: 소성모델

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Effect of Plastic Gradient from GND on the Behavior of Polycrystalline Solids (GND 효과에 의한 소성 구배의 다결정 고체 거동에 대한 영향)

  • Chung, Sang-Yeop;Han, Tong-Seok
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.2
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    • pp.185-191
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    • 2011
  • Plastic gradient from geometrically necessary dislocation(GND) can affect material behavior significantly. In this research, mechanical behavior of polycrystalline solid is investigated using the finite element method incorporating plastic gradient from long range dislocation or GND effect. Plastic gradient effect is implemented in the analysis model by considering a long range strain term as well as elastic and plastic terms in the multiplicative decomposition. In the model, gradient hardness coefficient and length parameter are used to evaluate the effect of the long range strains and sensitive study is conducted for the parameters. It is confirmed that the GND amplifies hardening response of polycrystals compared with the single crystal.

The Parameters of the Bounding Surface Plasticity Model in the Isotropically Consolidated Clay (등방압밀점토에서 항복경계면 소성모델의 매개변수)

  • 이영생;김원영
    • Geotechnical Engineering
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    • v.12 no.4
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    • pp.21-32
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    • 1996
  • To predict the stress-strain behavior of the soil more approximately, the concept of the critical state soil mechanics was added to the plasticity increment theory in the bounding surface Plasticity model. This model was constituted with two ellipse and one hyperbola in older to describe the behaviour of the isotropically consolidated soil. Thus, this model is very complicate due to the various parameters used. Therefore, the accurate understanding and skill of the theory is required in order to apply this model to the practical geotechnical problems. In the present paper, the bounding surface shape paraiheter R and A, the mapping center parameter C among various parameters used were varied and the results were numerically analized. Finally, each sensitivity with respect to monotonic and cyclic loading was analized and the range of the value of the each parameter was proposed.

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p-Version Finite Element Analysis of Elasto-Plastic Cracked Plates Including Strain Hardening Effects (변형률 경화효과를 고려한 탄소성 균열판의 p-Version 유한요소해석)

  • 우광성;홍종현;윤영필
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.4
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    • pp.537-549
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    • 1999
  • 선형탄성 파괴해석은 균열을 갖는 변형률 경화재료의 파괴거동을 예측하는데 불충분하기 때문에 최근에는 균열 선단 부에서 대규모 소성 역을 갖는 균열 체에 적용할 수 있는 많은 파괴역학개념이 제안되고 있다. 따라서, 본 연구에서는 대규모항복 조건하의 연성파괴를 보이는 평판을 정확하게 해석할 수 있는 새로운 유한요소모델을 제시하고자 한다. 균열 선단 부의 응력 장을 정의하는데 가장 지배적인 파괴매개변수인 J-적분 값과 소성 역의 크기 및 형상을 J-적분법과 등가영역적분법을 통해 파괴거동을 설명할 수 있도록 증분소성이론에 기초를 둔 p-version 유한요소해석이 채택되었다. 제안된 유한요소모델에 의한 수치해석결과는 이론 해와 h-version 유한요소해석과 비교되었다.

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Realistic Cloth Simulation using Plastic Deformation (소성변형특성을 이용한 사실적인 직물 시뮬레이션)

  • Oh Dong-Hoon;Jung Moon-Ryul;Song Chang-Geun;Lee Jong-Wan
    • Journal of KIISE:Computing Practices and Letters
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    • v.12 no.3
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    • pp.208-217
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    • 2006
  • This paper presents a cloth simulation technique that implements plastic deformation. Plasticity is the property that material does not restore completely to the original state once deformed, in contrast to elasticity. We model cloth using a particle model, and posit two kinds of connections between particles, i.e. the sequential connections between immediate neighbors, and the interlaced connections between every other neighbors. The sequential connections represent the compression and tension of cloth, and the interlaced connections the bending in cloth. The sequential connections are modeled by elastic springs, and the interlaced connections by elastic or plastic spring depending on the amount of the current deformation of the connections. Our model is obtained by adding plastic springs to the existing elastic particle model of cloth. Using the new model, we have been able to simulate bending wrinkles, permanently deformed wrinkles, and small wrinkles widely distributed over cloth. When constructing elastic and plastic spring models for sequential and interlaced connections, we took pain to prevent the stiffness matrix of the whole cloth system from being indefinite, in order to help achieve physical stability of the cloth motion equation and to improve the effectiveness of the numerical method.

Reinforcement Effect of Viscoplastic Rockboft - Numerical Study (록볼트 점소성 거동에 의한 지보효과 분석 - 수치해석)

  • 조태진;이정인
    • The Journal of Engineering Geology
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    • v.3 no.3
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    • pp.215-230
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    • 1993
  • In-situ rock mass demonstrates the variety of structural features, and especially the mechanical and spatial characteristics of joint (or joint system) greatly affect the deformation and fallure strength of the rock mass. In this study finite element model capable of analyzing the viscoplastic behavior of reinforced jointed rock mass has been developed based on equivalent material approach. Accuracy and reliability of the numerical model have verified by simuiating the behavior of simplified block model and comparing the results with analytic solutions. Practical applicability was also demonstrated by analyzing the time-dependent behavior of underground oil storage tunnel and assessing the reinforcement effect of rockbolt.

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Evaluation of Rotation Capacity of Steel Moment Connections ConsideringInelastic Local Buckling - Model Development (비탄성 국부좌굴을 고려한 철골 모멘트 접합부 회전능력 평가를 위한 모델 개발)

  • Lee, Kyung Koo
    • Journal of Korean Society of Steel Construction
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    • v.20 no.5
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    • pp.617-624
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    • 2008
  • Well-designed steel moment connections will undergo local buckling before they exhaust their available rotation capacity, and inelastic post-buckling deformation plays a major role in defining the connection rotation capacity. An approximate analytical method to model strength degradation and failure of beam plastic hinges due to local buckling and estimation of the seismic rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames under both monotonic and cyclic loading conditions is proposed in this study. This method is based on the plastic mechanism and a yield line plastic hinge (YLPH) model whose geometry is determined using the shapes of the buckled plastic hinges observed in experiments. The proposed YLPH model was developed for the improved WUF-W and RBS connections and validated in comparison with experimental data. The effects of the beam section geometric parameters on the rotation capacity were discussed in the companion paper (parametric studies).

A Study on Generalization of Cyclic Plasticity Model and Application of 3-Dimensional Elastic-Plastic FEM of SM570 (SM570강재의 반복소성모델의 정식화 및 3차원 탄소성 유한요소적용에 관한 연구)

  • 장경호;장갑철;이은택
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.1
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    • pp.59-65
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    • 2004
  • Recently, as steel structures become higher and more long-spanned, application of high strength steel. SM570, is considered, For accurate seismic design, seismic analysis of steel structures needs a constitutive equation describing the characteristic of steel materials under non-proportional cyclic loading, While the use of SM570 material is much increased these days, research for description and generalization of cyclic plasticity behavior are insufficient, In this study, a cyclic plasticity model is proposed by results of material tests, i.e, monotonic and low cycle tests, Proposed cyclic plasticity model is applied to 3-Dimensional FE program and we carried out seismic analysis of pipe-section steel pier using SM570, Comparison between experiment and analysis results shows that the proposed constitutive equation is able to describe exactly the complicated plastic behavior of steel structure using SM570.

Elasto-Plastic Anisotropic-Damage Model for Concrete (콘크리트의 탄-소성 이방성-손상 모델)

  • 이기성;송하원
    • Computational Structural Engineering
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    • v.9 no.1
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    • pp.65-76
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    • 1996
  • The initiation and growth of microcracks or microvoids inside concrete results in the progressive degradation of concrete. This damage processing along processing along with plastic deformation is main cause of nonlinear behavior of concrete. In this study, a continuum damage model of concrete is developed for the analysis of the nonlinear behavior of concrete due to damage and elasto-plastic deformation. Anisotropic damage tensor is used to describe the anisotropy of concrete and hypothesis of equivalent elastic energy is used to define the effective elastic tensor. The damage model including the damage evolution law and constitutive equation is derived with damage variable and damage surface which is defined by damage energy release rate by using the Helmholtz free energy and dissipation potential based on the thermodynamic principles. By adopting a typical plasticity model of concrete, plasticity of concrete is included to this model. Afinite element analysis program implemented with this model was developed and finite element analysis was performed for the analyses of concrete subjected to uniaxial and biaxial loadings. Comparison of the results of analysis with those of experiments and other models shows that the model successfully predicts the nonlinear behavior of concrete.

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Unified Method for Nonlinear Finite Element Analysis of RC Planar Members (통합방법을 이용한 철근콘크리트부재의 비선형 유한요소해석)

  • 박홍근
    • Magazine of the Korea Concrete Institute
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    • v.9 no.2
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    • pp.133-144
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    • 1997
  • Concrete plasticity models fol the analysis of reinforced concrete members in plane stress are studied. The proposed plasticity model for reinforced concrete provides a unified approach combining plasticity theory and damage models. It addresses strength mhancement under rnultiaxial compression. and tensile cracking damage. The model uses multiple failure criteria for compressive crushing and tensile cracking. For tensile cracking behavior. rotating-crack and fixed-crack plasticity models are compared. As crushing failure criterion, the Drucker-Prager and the von Mises models are used for comparison. The model uses now and existing damnge models fbr tension softening, tension stiffening. and compression softening dup to tensilt. cracking. Finite element analyses using the unified method are compatxd with existing rxpcrimcntal r.esults. To vei.ify the proposcd crushing and cracking plasticity models, the experiments have load capacities govc11.nc.d either by compressive crushing of'concrete or by yi~lding of' reinforcing steel.