• Title/Summary/Keyword: Deformation

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Prediction of High Temperature Plastic Deformation Variables on Al 6061 Alloy (Al 6061 합금의 고온 소성변형 조건의 예측)

  • 김성일;정태성;유연철;오수익
    • Transactions of Materials Processing
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    • v.8 no.6
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    • pp.576-582
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    • 1999
  • The high temperature behavior of Al 6061 alloy was characterized by the hot torsion test in the temperature ranges of 400∼550℃ and the strain rate ranges of 0.05∼5/sec. To decide optimum deformation condition, three types of deformation maps were individually made from the critical strain (εc). deformation resistance(σp) and deformation efficiency (η). The critical strain(εc) for dynamic recrystallization (DRX) which was decided from the inflection point of strain hardening rate(θ) - effective stress (σ) curve was about 0.65 times of peak strain (εp). The relationship among deformation resistance (peak stress, σp), strain rate (ε), and temperature (T) could be expressed by ε=2.9×1013[sinh(0.0256σp]7.3exp (-216,000/RT). The deformation efficiency (η)which was calculated on the basis of the dynamic materials model (DMM) showed high values at the condition of 500∼550℃, 5/sec for 100% strain. The results from three deformation maps were compared with microstructures. The best condition of plastic deformation could be determined as 500℃ and 5/sec.

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A Study of Plastic Deformation Mechanisms in $Fe_3$Al Intermetallics Alloys by Inelastic Deformation Theory (비탄성 변형이론을 이용한 $Fe_3$Al 금속간화합물의 소성변형 기구 고찰)

  • 정호철
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.180-183
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    • 1999
  • It is well known that Fe3Al intermetallic compound shows an anomalous peak of the yield strength at about 50$0^{\circ}C$ and then decrease at higher temperatures The dislocation structure was examined by transmission electron microscopy and high temperatures. The dislocation structure was examined by transmission electron microscopy and high temperature mechanical properties were examined by tensile and load relaxation tests. The flow stress curves obtained from load relaxation tests were then analyzed in terms of internal variable deformation theory. it was found that the flow curves consisted of three micro-deformation mechanisms -i. e inelastic deformation mode plastic deformation mode and dislocation creep deformation mode depending on both dislocation structure and deformation temperature. The flow curves could be well described by the constitutive equations of these three micro-deformation mechanisms based on the internal variable deformation theory.

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SENSITIVITY OF SHEAR LOCALIZATION ON PRE-LOCALIZATION DEFORMATION MODE

  • Kim, Kwon--Hee-
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.83-102
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    • 1992
  • As shear localization is observed in different deformation modes, an attempt is made to understand the conditions for shear localization in general deformation modes. Most emphasis in put upon the effects of pre-localization deformation mode on the onset of shear localization and all the other well-recognized effects of subtle constitutive features and imperfection sensitivity studied elsewhere are not investigated here. Rather, an approximate perturbation stability analysis is performed for simplified isotropic rigid-plastic solids subjected to general mode of homogeneous deformation. Shear localization is possible in any deformation mode if the material has strain softening. The incipient rate of shear localization and shear plane orientations are strongly dependent upon the pre-localization deformation mode. Significant strain softening is necessary for shear localization in homogeneous axisymmetric deformation modes while infinitesimal strain softening is necessary for shear localization in plane strain deformation mode. In any deformation mode, there are more than one shear plane orientation. Except for homogeneous axisymmetric deformation modes, there are two possible shear plane orientations with respect to the principal directions of stretching. Some well-known examples are discussed in the light of the current analysis.

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Effects of the Support Condition on Out-of-plane Deformation by Welding (정반의 지지조건이 용접 면외변형에 미치는 영향)

  • 박정웅;고대은;신용택;이해우;이재원
    • Journal of Welding and Joining
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    • v.17 no.5
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    • pp.55-60
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    • 1999
  • In thin plate welding, welding deformation is deformation is produced in special form like buckling distortion, which is different from one in thick plate welding, large quantitatively, and has complicated form. Therefore, a particular countermeasure to prevent the welding deformation in manufacturing process is requested. Otherwise it takes more time to straighten the welding deformation than to fabricated a steel structure newly and in case of failing to straighten the welding deformation in beginning of the flame straightening process, even if the flame straitening is completed, the appearances is not good and sometimes eve refabrication is needed. To minimize these problems. In this present paper, the effects of the condition of support pin on out-of plane deformation produced by thin plate Butt welding in investigated through experiment and the countermeasure to prevent the welding deformation in suggested.

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Study on the Weld-Induced Deformation Control of Panel Blocks (블록조립시 변형제어에 관한 연구)

  • 이주성
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.275-278
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    • 2000
  • This paper is concerned with the simulator to estimate deformation due to welding of panel blocks. An efficient computer program system has been developed which can be applied both to estimation of weld-induced deformation under the given welding conditions and to reflection of effect when methods for deformation control are applied. This paper briefly describes the background of the present simulator and sows some results applying the simulator to estimation of weld-induced deformation. In addition results when methods for deformation control are applied are also included.

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Collision Configurations Reconstruction Using Deformation Shape and Deformation Severity of Car Body (차체의 변형상과 변형정도에 의한 자동차 충돌상황의 재구성)

  • 장인식;채덕병
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.1
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    • pp.171-180
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    • 2001
  • Collision accident reconstruction algorithm are developed based on the deformation shape and severity of a car body. At first, the body stiffness equation representing the force-deformation relationship is derived using finite element analysis for head on collision of two cars. The database of deformation shapes and energies is constructed for five different collision configurations; each configuration contains three velocity conditions. Deformation shapes are obtained using a curve fitting method and result in cubic polynomials. Deformation energies are calculated using a stiffness equation and deformation data. Three algorithms are developed to reconstruct collision configuration compared with constructed database. The developed algorithms show reasonably good performance to find collisions conditions for some test problems.

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Shape deformation and wear sensation in wearing on support type panty stocking (고탄력 팬티스타킹 착용에 의한 형태변형 및 착용감)

  • 류현혜;성수광
    • Journal of the Ergonomics Society of Korea
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    • v.14 no.1
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    • pp.37-57
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    • 1995
  • The purpose of this study was to investigate the elastic effect of deformation and restriction in wearing a support type panty stocking (PS). The study investigated deformation rate in all surface area, deformation rate in local area, length deformation rate, changes in slip and feeling of restriction under the standard laboratory condition. Two healthy adult females in twenties wore four types of PS. The result were as follows : The deformation rate in all surface area was 117 .approx. 132% in wearing support type PS, 157% in wearing mono type PS, due to the intensities of restriction. The deformation rate in local area was in order, course > oblique > wale direction. The largest deformation rate was observed in hip girth. Between the deformation rates in all surface and local areas was a high correlation acknowledged, especially the course direction showed a high correlation. Support type PSs showed more deformation and changes of slip than wool and mono type PS. Especially, changes of slip at the knee appeared greatly. The responses of restriction evaluated from a paired comparison method were in order, JS 2 > KS 4 > KS 9 > KS 5 > KS 1 > KM 3.

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A Study on the Temperature Distribution and Deformation of Case in Shrinkage Fit Process(II) - Deformation Measurement and Deformation Analysis Model - (열박음 공정이 케이스의 온도분포 및 변형에 미치는 영향(II) - 변형 계측 및 변형 해석 모델 정립 -)

  • 장경복;정진우;강성수;최규원;박찬우;조상명
    • Journal of Welding and Joining
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    • v.19 no.5
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    • pp.492-498
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    • 2001
  • In the previous study, temperature monitoring of case about shrinkage fit process was performed and heat transfer model was developed in detail by feedback and tuning among monitoring result, process investigation, and analysis result. The gap element in contact between case and core was effectively used in analysis model. In present study, following things are performed to solve deformation of case due to shrinkage fit process on the basis of previous result. Above all, mechanical material properties of case are measured by case specimen for deformation analysis considering weldment of case. Deformation of case before and after shrinkage fit process is measured, too. Three dimensional deformation model is developed by the comparison and inspection between these experimental data and analysis results. Deformation analysis is simulated with the result of heat transfer analysis, in other words, non-coupled analysis is used. Finally the countermeasure for deformation is brought up through those.

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Biaxial Compressive Deformation Characteristics and Microstructure Change in a Round Copper Pipe (원형 동관의 2축압축 변형특성 및 조직변화에 관한 연구)

  • Yoo, C.K.;Won, S.T.
    • Transactions of Materials Processing
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    • v.22 no.2
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    • pp.67-73
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    • 2013
  • The deformation characteristics and microstructure changes in a round copper pipe under biaxial compression was studied using a horizontal compression die. The change of material properties, punch load and deformation behavior were monitored using various compressive deformation rates in the range of 0.5mm/min.~450mm/min. The strains, either tensile or compressive, were estimated from Vickers microhardness test results. The punch load and deformation characteristics of the round copper pipes were found to change greatly at a deformation rate of about 200mm/min. The punch load decreased with increasing compressive deformation rate. The results of numerical simulations agreed well with what was expected from the final microstructure and the hardness profile estimated from the final deformation strains.

Effect of Die-upset Process on Magnetic Properties and Deformation Behavior of Nanostructured Nd-Fe-B Magnets

  • Zhao, R.;Zhang, W.C.;Li, J.J.;Wang, H.J.;Zhu, M.G.;Li, W.
    • Journal of Magnetics
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    • v.16 no.3
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    • pp.294-299
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    • 2011
  • Nd-Fe-B high performance magnets were prepared by die-upset forging. The effects of the deformation parameters on magnetic properties and flow stress were studied. Deformation temperatures in the range of $600{\sim}900^{\circ}C$ enable to achieve an effective anisotropy and temperature $800^{\circ}C$ proves to be suitable for deformation of Nd-Fe-B magnets. The amount of c-axis alignment along the press direction seems to depend on the amount of deformation and a saturation behavior is shown at deformation ratio of 75%. Magnetic properties are also related to strain rate, and maximum energy product is attained at an optimum strain rate of ${\varphi}=1{\times}10^{-2}s^{-1}$. By analyzing the relationship of stress and strain at different deformation temperature during die-upset forging process, deformation behavior of Nd-Fe-B magnets was studied and parameters for describing plastic deformation were obtained. Nd-rich boundary liquid phase, which is additionally decreasing the flow stress during deformation, is supposed to play the role of diffusion path and enhance the diffusion rate.