• Title, Summary, Keyword: 일반 평면응력조건

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Viscoplastic Solution of Thick Walled Cylinder Considering Axial Constraint (축방향 경계 조건을 고려한 두꺼운 실린더의 점소성 응력해)

  • Yoon, Sam-Son;Lee, Soon-Bok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.9
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    • pp.1555-1561
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    • 2003
  • Finite element analysis using modern constitutive equation is one of the most general tools to simulate the deformation behavior and to predict the life of the structure. Constitutive equation becomes complicated so as to predict the material behavior more accurately than the classical models. Because of the complexity of constitutive model, numerical treatment becomes so difficult that the calculation should be verified carefully. One-element tests, simple tension or simple shear, are usually used to verify the accuracy of finite element analysis using complicated constitutive model. Since this test is mainly focused on the time integration scheme, it is also necessary to verify the equilibrium iteration using material stiffness matrix and to compare FE results with solution of structures. In this investigation, viscoplastic solution of thick walled cylinder was derived considering axial constraints and was compared with the finite element analysis. All the numerical solutions showed a good coincidence with FE results. This numerical solution can be used as a verification tool for newly developed FE code with complicated constitutive model.

A Study on the Angle of Localization of a Metal Specimen under Uniaxial Tension with Plane Strain Condition (평면 변형 조건에서 일축 인장력을 받는 금속 재료의 불연속 변위 각에 대한 연구)

  • Park, Jae-Gyun;Kim, Mi-Rim
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.3
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    • pp.275-281
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    • 2011
  • When a flat bar type metal specimen for general tension test is subject to incremental uniaxial tension, a narrow plastic shear band, so called luders band, is generated at some instance. This band typically has an angle to the axis of specimen and many early researches have been done to investigate the condition and angle of this localized deformation phenomenon by many researchers. This study follows the procedure of Thomas(1961) under plane stress boundary condition. $J_2$ plasticity theory, balance of linear momentum, and constitutive equations are used to derive the angle of luders band under plain strain boundary condition. The result was confirmed by other angle based on acoustic tensor theory.

Stress-Strain Characteristics of Weathered Granite Soil in Plane Strain Test (평면변형시험을 이용한 화강풍화토의 응력-변형률 특성)

  • Kim, You-Seong;Lee, Jin-Kwang;Kim, Jae-Hong
    • Journal of the Korean Geotechnical Society
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    • v.30 no.5
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    • pp.37-46
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    • 2014
  • Geotechnical structures have been analyzed and constructed in various geometry conditions to maintain their stability in accordance with the characteristics of construction design. Shear strengths are generally obtained from triaxial test to apply to design analysis. Geotechnical structures under strip loading, such as earth dam, embankment, and retaining wall, have the strain in a direction, and plane strain condition. Thus, an approximate shear strengths should be applied for stability analysis suitable to ground condition. When applying shear strengths obtained from triaxial tests for slope stability analysis, the evaluation of it may underestimate the factor of safety because the implementation is not suitable for geometry condition. The paper compares shear strengths obtained from triaxial test and plane strain test based on various relative densities using weathered granite soils. Additionally, yield stress is determined by maximum axial strain 15% in triaxial test because of continuous kinematic hardening, but plane strain test can determine a failure point in critical state to evaluate the shear strengths of soils at the second plastic hardening step. This study proposes to perform an appropriate test for many geotechnical problems with plane strain condition.

The Free Edge Stress Singularity At An Interface of Bilinear Material Structure (탄성 선형 경화 재료로 구성된 복합 구조물의 자유 경계면에서 나타나는 응력특이도)

  • 정철섭
    • Computational Structural Engineering
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    • v.10 no.3
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    • pp.185-193
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    • 1997
  • The order of the stress singularity that occurs at the termination of an interface between materials exhibiting bilinear stress-strain response under plane strain conditions has been calculated, The governing equation of elasticity together with traction-free boundary condition and interface continuity condition defines a two-point boundary value problem. The stress components near the free edge are assumed to be proportional to r/sup s-1/, with solutions existing only for certain values of s. Finding these values entails the solution of an eigenvalue problem. Because it has been impossible to integrate the differential equations analytically, the integration has been performed numerically with a shooting method coupled with a Newton improvement scheme.

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Influence of Stress Shape Function on Analysis of Contact Problem Using Hybrid Photoelasticity (광탄성 실험 하이브리드 법에 의한 접촉응력 해석시 응력형상함수의 영향)

  • Shin, Dong-Chul;Hawong, Jai-Sug
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.3
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    • pp.345-352
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    • 2013
  • In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work.

Behaviour of Foundation Ground with Marine Clay in Anisotropy (이방성을 갖는 해성점토 기초지반의 거동해석)

  • Kim, Myeon-Su;Lee, Kang-Il;Kim, Chan-Ki;Yun, Jung-Mann;Baek, Won-Jin
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.1
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    • pp.11-21
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    • 2015
  • This study aims at investigating of the behavioral characteristics of foundation ground subjected to a strip load in anisotropy. Using marine clays sampled at Shihwa area, a series of laboratory tests including triaxial compressive test, plane strain compressive and expansion tests that allows horizontal deformation only and zero strain (${\varepsilon}_2$) in the direction of intermediate stress (${\sigma}_2$) are conducted. In addition, a numerical analysis using parameters obtained from the tests is carried out. In the numerical analysis, Cam-clay model that simulates the behavior of natural deposited clay properly is adopted. The analysis results show that the vertical displacements of the plane strain compressive tests are relatively larger than those of triaxial compressive tests by 18-25%. Likewise, the horizontal displacements is 13-19% larger.

Fuzzy Optimum Design of Plane Steel Frames Using Refined Plastic Hinge Analysis and a Genetic Algorithm (개선소성힌지해석과 유전자 알고리듬을 이용한 평면 강골조 구조물의 퍼지최적설계)

  • Lee, Mal Suk;Yun, Young Mook;Shon, Su Deok
    • Journal of Korean Society of Steel Construction
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    • v.18 no.2
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    • pp.147-160
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    • 2006
  • GA-based fuzzy optimum design algorithm incorporated with the refined plastic hinge analysis method is presented in this study. In the refined plastic hinge analysis method, geometric nonlinearity is considered by using the stability functions of the beam-column members. Material nonlinearity is also considered by using the gradual stiffness degradation model, which considers the effects of residual stresses, moment redistribution through the occurence of plastic hinges, and the geometric imperfections of the members. In the genetic algorithm, the tournament selection method and the total weight of the steel frames. The requirements of load-carrying capacity, serviceability, ductility, and constructabil ity are used as the constraint conditions. In fuzzy optimization, for crisp objective function and fuzzy constraint s, the tolerance that is accepted is 5% of the constraints. Furthermore, a level-cut method is presented from 0 to 1 at a 0 .2 interval, with the use of the nonmembership function, to solve fuzzy-optimization problems. The values of conventional GA optimization and fuzzy GA optimization are compared in several examples of steel structures.

Train-Structure Dynamic Interaction Analysis of The Bridge Transition Considering Track Irregularity (궤도틀림을 고려한 교대접속부의 열차상호동적거동해석)

  • Choi, Chan-Yong;Kim, Hun-Ki;Chung, Keun-Young;Yang, Sang-Beom
    • Journal of the Korean Geotechnical Society
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    • v.31 no.9
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    • pp.29-38
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    • 2015
  • In this study, track dynamic interaction characteristics caused by the vehicle running through transitional section such as bridge abutments were studied using the finite element analysis program. The geometric condition of track was generated by trigonometric function and allowable maximum track irregularity is determined by KORAIL track maintenance criteria. The sub-infrastructure under rail fastener system was modelled by 3D solid elements. To reduce computational cost only half track line is numerically considered and the roller boundary condition was applied to each side of model. In this study, the vehicle-track dynamic interaction analysis was carried out for standard Korean transition section of concrete track and the dynamic behaviors were investigated. The dynamic characteristics considered are wheel load variation, vertical acceleration at body, and maximum Mises stress at each part of transitional section.

Multi-Objective Fuzzy Optimization of Structures (구조물에 대한 다목적퍼지최적화)

  • Park, Choon-Wook;Pyeon, Hae-Wan;Kang, Moon-Myung
    • Journal of Korean Society of Steel Construction
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    • v.12 no.5
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    • pp.503-513
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    • 2000
  • This study treats the criteria, considering the fuzziness occurred by optimization design. And we applied two weighting methods to show the relative importance of criteria. This study develops multi-objective optimization programs implementing plain stress analysis by FEM and discrete optimization design uniformaly. The developed program performs a sample design of 10-member steel truss. This study can carry over the multi-objective optimization based on total system fuzzy-genetic algorithms while performing the stress analysis and optimization design. Especially, when general optimization with unreliable constraints is cannot be solve this study can make optimization design closed to realistic with fuzzy theory.

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Parametric Studies of Slope stability Analysis by 3D FEM Using Strength Reduction Method (강도감소법에 의한 3차원 사면안정해석에 대한 매개변수 연구)

  • Kim, Young-Min
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.4
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    • pp.25-32
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    • 2016
  • The two-dimensional (2D) analysis is widely used in geotechnical engineering for slope stability analysis assuming a plane-strain condition. It is implicitly assumed that the slip surface is infinitely wide, and thus three-dimensional (3D) end effects are negligible because of the infinite width of the slide mass. The majority of work on this subject suggests that the 2D factor of safety is conservative (i.e. lower than the 'true' 3D factor of safety). Recently, the 3D finite element method (FEM) became more attractive due to the progress of computational tools including the computer hardware and software. This paper presents the numerical analyses on rotational mode and translational mode slopes using the 2D and 3D FEM as well as 2D limit equilibrium methods (LEM). The results of the parametric study on the slope stability due to mesh size, dilatency angle, boundary conditions, stress history and model dimensions change are analysed. The analysis showed that the factor of safety in 3D analysis is always higher than that in the 2D analysis and the discrepancy of the slope width in W direction on the factor of safety is ignored if the roller type of W direction conditions is applied.