• Structural Engineering and Mechanics
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• 제6권2호
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• pp.217-227
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• 1998

An elasto-plastic finite element procedure using degenerated shell element with assumed strain field technique considering both material and geometric nonlinearities has been developed. This assumes von-Mises yield criterion, von-Karman strain displacement relations and isotropic hardening. A few numerical examples are presented to demonstrate the correctness and applicability of the method to different kinds of engineering problems. From present study, it is seen that there is a considerable improvement in the displacement valuse when both material and geometric nonlinearities are considered. An example of the spread of plastic zones for isotropic and anisotropic materials has been illustrated.

• 소성∙가공
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• 제30권2호
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• pp.83-90
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• 2021

In this paper, a parametric study on the influence of friction between materials on pull force in single clinching is conducted using an axisymmetric elasto-plastic finite element method and law of Coulomb friction. An appropriate finite element analysis model is given, which minimizes the effect of the material model and numerical factors including the number of quadrilateral finite elements and blank radius. It is emphasized that the elasto-plastic material model should be employed because the elastic deformation of the internal region is affected more by the pull force. It has been shown that the pull force increases as friction coefficient increases and that the optimized friction coefficient is around 0.4, which is qualitatively comparable with its theoretical value. When the friction coefficient reaches 0.5 in the example studied, the neck fracture is predicted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.334-339
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• 2003

The welding residual stress has on important effect on welding deformation, fatigue fracture, buckling strength, brittle fracture, etc. For the purpose of relaxation of welding residual stress, post welding heat treatment is widely used. In this paper, residual stresses were calculated by two dimensional thermal elasto-plastic analysis using finite element method. Heat transfer analysis are performed by transient analysis. Also structure analysis are carried out by of thermal-mechanical coupled analysis. Numerical analysis are used by ANSYS 5.7.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.487-504
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• 2006

Several new versatile two-dimensional p-version finite elements are developed. The element matrices are integrated analytically to guarantee the accuracy and monotonic convergence of the predicted solutions of the proposed p-version elements. The analysis results show that the convergence rate of the present elements is very fast with respect to the number of additional Fourier or polynomial terms in shape functions, and their solutions are much more accurate than those of the linear finite elements for the same number of degrees of freedom. Additionally, the new p-version plate elements without the reduced integration can overcome the shear locking problem over the conventional h-version elements. Using the proposed p-version elements with fast convergent characteristic, the elasto-plastic impact of the structure attached with the absorber is simulated. Good agreement between the simulated and experimental results verifies the present p-version finite elements for the analyses of structural dynamic responses and the structural elasto-plastic impact. Further, using the elasto-plastic impact model and the p-version finite element method, the absorber of the T structure on the Qiantang River is designed for its collision protection.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.231-234
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• 2008

This paper is concerned with the analysis of elasto-plastic stress waves by a time discontinuous variational integrator based on Hamiltonian in order to more accurate results in one dimensional dynamic problem. The proposed algorithm adopts both time-discontinuous variational integrator and space-continuous Hamiltonian so as to capture discontinuities of stress waves. This study enables to preserve total mechanical energy such as internal energy, kinetic energy and dissipative energy due to plastic deformation for long integration time. Finite element analysis of elasto-plastic stress waves is carried out in order to demonstrate the accuracy of the proposed algorithm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.93-96
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• 2001

Design sensitivity is calculated in the sheet metal forming process with an elasto-plastic finite element analysis and a direct differentiation method The sensitivity analysis is concerned with the time integration the constitutive relation considering planar anisotropy, shell elements and the contact scheme. The present result is compared with the result obtained with the finite difference approach in deep drawing processes. The obtained sensitivity information is applied to the simple optimization process for the sheet metal forming process.

• 전산구조공학
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• 제4권1호
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• pp.73-82
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• 1991

판의 탄소성 좌굴문제는 판 구조의 해석과 설계시의 중요성으로 인하여 상당한 관심이 모아져 온 분야이다. 본 연구에서는 유한요소법에 의한 효율적인 탄소성 좌굴해석 프로그램을 개발하였다. 탄소성 강성행렬을 구성하기 위한 소성이론으로는 실험결과와 잘 일치하는 Stowell의 변형이론을 사용하였으며, 좌굴하중을 해석하기 위해서는 고유치해석에 의한 반복기법을 사용하였다. 고유치해석에서는 불필요한 고유치의 계산을 피할 수 있는 subspace반복기법을 사용하였다. 해석결과를 Stowell이 제시한 이론해와 Pride에 의한 실험결과와 비교하여 프로그램의 타당성을 보이고, 이를 이용하여 단순지지, 또는 고정된 경계조건에 대하여 일축 또는 이축응력이 작용되는 여러 경우에 대하여 좌굴하중을 구하였다. 또한, 탄소성 좌굴에 미치는 형상비의 영향을 검토하였다.

• 터널과지하공간
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• 제10권2호
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• pp.173-179
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• 2000

절리면의 전단거동에서 나타나는 응력 및 변위의 비선형 특성을 탄소성해석에 의해 모사하는 경우 소성유동법칙이 해석결과에 미치는 영향을 검토하였다. Plesha의 절리구성모델을 적용하여 일정수직응력조건과 일정수직변위조건에서 수치직접전단시험을 실시하였다. 연상유동법칙을 적용하면 과도한 수직팽창이 예측되는 반면에 비연상유동법칙을 적용한 해석은 실제 절리거동을 잘 모사하고 있음을 보였다. 비연상유동법칙의 적용으로 강성행렬이 비대칭이 피는 단점을 보완하기 위해 비연상유동법칙을 적용하는 경우라도 요소의 접선강성행렬을 대칭화시키는 수치해석 기법이 제안되었다. 본래의 절리면과 동일한 소성변형을 일으키지만 연상유동법칙을 따르는 등가의 절리면을 가정함으로써 대칭인 탄소성행렬을 유도하였다. 일정수직음력조건에서 수티 직접전단시험을 실시하여 제안된 강성행렬 대칭화 기법의 유효성을 검증하였다.

• 대한기계학회논문집
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• 제12권2호
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• pp.185-192
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• 1988

본 논문에서는 접촉문제를 보다 정교하게 수식화 함으로써 효율적인 볼 압입 시험 시뮬레이션 방법을 제시하고 이를 실제에 적용하여 방법의 유용성을 보이고자 한다. 아울러 실험을 병행하여 결과를 비교함으로써 해석결과의 신뢰성을 검토한다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1996년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.27-28
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• 1996