• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 춘계학술대회논문집
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• pp.107-113
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• 1995

To investigate the behavior of platic deformation inaxisymmetric hot extrusion through square dies, the physical modelling with the plasticine as a model material is carried out at the room temperature. Some mechanical properties of the model material are determined by compression and ring compression tests. Visioplasticity method using experimetal grid distortion is introduced to anlayze the plastic flow, strain rate and strain distribution.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.73-78
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• 2001

In this study, the friction weldability and properties of inconel alloy(IN738LC) to stainless steel (STS304) was investigat-ed. Upset length increased according to increment of friction pressure and time. The tensile strength of the friction weld-ing reached 85% of the STS304 base metal strength under the conditions of 8 sec friction time, 50MPa friction pressure and 150 MPa upset pressure. From the result of fracture surface analysis, IN738LC section can be joined with STS 304 materials in shape of a convex lens. Also, the temperature of welded interface was measured with k-type thermocouple. Finally the plastic flow confirmed at the welded interface STS304 by micro test.

• 한국해양공학회지
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• 제14권2호
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• pp.70-75
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• 2000

In this paper a new constitutive model for ductile materials was proposed. This model can describe the material degradation due to the evolution of isotropic damage during elasto-platic deformation. The plastic flow rule was derived under the framework of thermodynamic approach of continuum damage mechanics(CDM) in which plastic strain hardening parameters and isotropic damage were taken as thermodynamic state variables. And the process to determine material constants for constitutive model using an experimental data was presented.

• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.1-4
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• 2001

For the practical use of a superconducting wire to magnet application, it is important to assess the Young modulus and other mechanical properties of HTS tapes. In order to establish a test method of mechanical properties for oxide composite superconductors. tensile tests of Bi-2223 multi- filamentary tapes were carried out at room temperature, as an activity of the International round robin test proposed by the committee of VAMAS/TWA 16-Subrgroup. The tapes consisting of mutli-filamentary showed a three stage tensile behavior. At the initial stage of the stress-streain curve. The elastic deformation existed in a quite nattrow strain region. But the plastic deformation was observed in a wide strain region due to the platic flow of the Ag alloy matrix. The results of RRT were also reported and discussed.

• 대한토목학회논문집
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• 제9권3호
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• pp.31-38
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• 1989

본 논문은 점진적 증가하중에 의한 철근 콘크리트 구조물의 전반적인 거동을 고찰하기 위한 것으로써 콘크리트의 인장균열, 철근 및 콘크리트의 응력-변형을 관계의 비선형성을 고려하였다. 콘크리트는 인장영역에서는 선형 탄성체로 가정하였으며 압축영역에서 탄소성체로 가정하였다. 압축영역의 콘크리트 거동을 파악함에 있어 Kupfer가 제안한 파괴표면 식을 항복한계로 사용 하였으며 associated flow rule에 의해 거동한다고 가정하였다. 철근은 일축응력을 받는 선형의 변형경화 재료로 모델링하였다. 콘크리트의 균열 발생시 인접한 균열 사이의 tension stiffening effect를 고려하였으며 콘크리트 구조물의 해석시 나타나는 유한요소의 크기에 따른 수치해석 오차를 콘크리트 인장부분의 변형연화 영역의 기울기를 보정함으로써 감소시키는 에너지 개념에 의한 ${\epsilon}_0$의 결정 모델 제안하였다.