• Title/Summary/Keyword: uniaxial deformation

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Deformation and Fracture Behavior of Structural Bulk Amorphous Metal under Quasi-Static Compressive Loading (준정적 압축하에서 구조용 벌크 아몰퍼스 금속의 변형 및 파괴거동)

  • Shin, Hyung-Seop;Ko, Dong-Kyun;Oh, Sang-Yeob
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.10
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    • pp.1630-1635
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    • 2003
  • The deformation and fracture behaviors of a bulk amorphous metal, Zr-based one (Zr$\_$41.2/Ti$\_$13.8/Cu$\_$12.5/Ni$\_$10/Be$\_$22.5/: Vitreloy), were investigated over a strain rate range (7x10$\^$-4/~4 s$\^$-1/). The uniaxial compression test and the indentation test using 3mm-diameter WC balls were carried out under quasi-static loading conditions. As a result, at the uniaxial compressive state, the fracture stress of the material was very high (~1,700MPa) and the elastic strain limit was about 2%. The fracture strength showed a strain rate independent behavior up to 4 s$\^$-1/. Using indentation tests, the plastic deformation behavior of the Zr-based BAM up to a large strain value of 15% could be achieved, even though it was the deformation under locally constrained condition. The Meyer hardness of the Zr-based BAM measured by static indentation tests was about 5 GPa and it revealed negligible strain hardening behavior. At indented sites, the plastic indentation occurred forming a crater and well-developed multiple shear bands were generated around it along the direction of 45 degree when the indentation load exceeded 7kN. With increasing indentation load, shear bands became dense. The fracture surface of the specimen after uniaxial compressive tests showed vein-like pattern, typical morphology of many BAMs.

DETERMINATION OF RUPTURE TIME AND STRAIN RATE IN CREEP BY UNIAXIAL TENSILE TEST

  • Oh, Hung-Kuk
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1994.10a
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    • pp.74-79
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    • 1994
  • The log-log presentation of stress versus Larson-Miller parameter is obtained by uniaxial tensile test instead of the long time creep test. The used material for example calculations is SUS304 stainless steel. The temperature of the uniaxial tensile test can be determined by the Larson-Miller parameter of the design stress and the 0.1hr's rupture time of the uniaxial tensile test. The rupture time at the design temperature and stress can be determined by the Larson-Miller parameter of the stress. The average creep rate is the total deformation of the tensile test divided by the rupture time at the design stress and temperature. The liner trend and the order of the data of the average creep rate by this method is almost same as that of experimental results.

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High-Temperature Rupture of 5083-Al Alloy under Multiaxial Stress States

  • Kim Ho-Kyung;Chun Duk-Kyu;Kim Sung- Hoon
    • Journal of Mechanical Science and Technology
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    • v.19 no.7
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    • pp.1432-1440
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    • 2005
  • High-temperature rupture behavior of 5083-Al alloy was tested for failure at 548K under multiaxial stress conditions: uniaxial tension using smooth bar specimens, biaxial shearing using double shear bar specimens, and triaxial tension using notched bar specimens. Rupture times were compared for uniaxial, biaxial, and triaxial stress conditions with respect to the maximum principal stress, the von Mises effective stress, and the principal facet stress. The results indicate that the von Mises effective and principal facet stresses give good correlation for the material investigated, and these parameters can predict creep life data under the multiaxial stress states with the rupture data obtained from specimens under the uniaxial stress. The results suggest that the creep rupture of this alloy under the testing condition is controlled by cavitation coupled with highly localized deformation process, such as grain boundary sliding. It is also conceivable that strain softening controls the highly localized deformation modes which result in cavitation damage in controlling rupture time of this alloy.

Buckling Analysis of Anisotropic Laminated Plates with Shear Deformation (전단변형을 고려한 이방성 적층판의 좌굴해석)

  • 최용희;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.10a
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    • pp.361-368
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    • 2001
  • This paper deals with the buckling load of antisymmetric angle-ply and cross-ply laminated rectangular plates. Buckling analysis is preformed for a simply supported, shear deformable laminated plate subjected to uniaxial compression and biaxial compression combined with uniform lateral pression. The shear deformation theory is considered to figure out a more exact behavior of laminated plates exactly. The purposes of this study are to formulate anisotropic laminated plates with shear deformation and to investigate the buckling load according to the various variables of laminated plates by using the exact solutions for anisotropic laminated plates having simply supported boundary.

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Prediction of Sheet Metal Necking with Anisotropic Hardening (이방성 가공경화를 고려한 냉간 압연강판의 넥킹 예측)

  • 인정제;김권희;함주희
    • Transactions of Materials Processing
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    • v.10 no.2
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    • pp.160-166
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    • 2001
  • Uniaxial necking is studied for steel sheets with initial anisotropy. The state of anisotropy is continuously altered by subsequent tensile deformation at angles to the rolling direction. The orientations of orthotropy axes are changed before the onset of necking. A simple hardening rule which incorporates the rotations of orthtropy axes is proposed and the necking strains are predicted at angles to the rolling direction. Predicted results show good agreement with the experiments.

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Derivation of constitutive equations of loose metal powder to predict plastic deformation in compaction (자유분말금속 압축시 소성변형예측을 위한 구성방정식의 유도)

  • Kim, Jin-Young;Park, Jong-jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.2
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    • pp.444-450
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    • 1998
  • In the present investigation, it is attempted to derive a yield function and associated flow rules of loose metal powders to predict plastic deformation and density change during compaction. The loose metal powders yield by shear stress as well as hydrostatic stress and the yield strength is much smaller in tension than compression. Therefore, a yield function for the powders is expressed as a shifted ellipse toward the negative direction in the hydrostatic stress axis in the space defined by the two stresses. Each of parameters A, B and .delta. used in the yield function is expressed as a function of relative density and it is determined by uniaxial strain and hydrostatic compressions using Cu powder. Flow rules obtained by imposing the normality rule to the yield function are applied to the analyses of unidirectional, bidirectional and hydrostatic compressions, resulting in an excellent agreement with experiments. The yield function is further examined by checking volume changes in plane stain, uniaxial strain and shear deformations.

A study on the formability with heat treatment and deformation temperature in warm hydroforming of Al 6061 tube (Al6061 tube의 열처리조건과 온도에 따른 액압성형성에 관한 특성 연구)

  • Yi H. K.;Lee Y. S.;Moon Y. H.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.255-258
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    • 2005
  • In this study, the effect of heat treatment conditions and deformation temperature on the formability were investigated in warm hydroforming of Al 6061 tube. Full annealing and T6-treatment for heattreatment of Al6061 tube were used in this study. To evaluate the hydroformability, uniaxial tensile test and bulge test were performed between room temperature and $300^{\circ}C$. And measured flow stress was used to simulate the hydroforming of Al 6061. A commercial FEM code, DEFORM2D, was used to calculate the damage and strain variation. The calculated values were efficient to predict the forming limit in hydroforming for real complex shaped part.

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A Study on Deformation Behaviors of Al 6061, 7075 Tube at Different Heat Treatments for Warm Hydroforming (온간액압성형공정 적용을 위한 알루미늄 6061, 7075 튜브의 열처리조건에 따른 변형특성연구)

  • Yi, Hyae-Kyung;Moon, Young Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.20 no.1
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    • pp.1-10
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    • 2007
  • The deformation behaviors of full annealed and T6 treated 6061, 7075 aluminum tubes are investigated at various temperature performing uniaxial tensile test. Full annealed Al 6061 and Al7075 tubes, and T6 treated Al7075 tube don't show sharp local necking with an elongation of 50% at $300^{\circ}C$. So it is expected that influenced by elevated tempterature. At $300^{\circ}C$ and strain rate of 0.001/s, many micro-cracks are observed in T6 treated Al 6061 tube, which is believed to be responsible for the decrease of total elongation.