• 제목/요약/키워드: Angular deformation

검색결과 212건 처리시간 0.038초

평 블록의 용접변형 제어 (Weld Induced Deformation Control of Panel Blocks)

  • 이주성
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2000년도 춘계학술대회 논문집
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    • pp.205-209
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    • 2000
  • This paper is concerned with development of the production-oriented structural design information system to predict the inaccuracy level of panel blocks and to consider the result at the structural design stage. Emphasis is placed on that the inaccuracy during production should likely be considered at the structural design stage to reduce the undesirable adjusting work and therefore to enhance the productivity. The primary goal of the present study is to consider the productivity and the efficient design at the same time for a high quality product of panel block. Usefulness of the developed information are illustrated through some application examples.

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진동전단유동장에서 점탄성 반고형 연고기제(바셀린)의 레올로지 거동 (Rheological Behavior of Viscoelastic Semi-Solid Ointment Base (Vaseline) in Oscillatory Shear Flow Fields)

  • 송기원;장갑식
    • Journal of Pharmaceutical Investigation
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    • 제36권1호
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    • pp.31-38
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    • 2006
  • Using a Rheometries Dynamic Analyzer (RDA II), the dynamic viscoelastic properties of a semi-solid ointment base (vaseline) in large amplitude oscillatory shear flow fields were measured over a temperature range of $25{\sim}45^{\circ}C$ and the linear viscoelastic behavior in small amplitude oscillatory shear flow fields was investigated over a wide range of angular frequencies. In this article, the nonlinear viscoelastic behavior was reported from the experimentally obtained data and the effect of temperature on this behavior was discussed in detail. In addition, the angular frequency and temperature dependencies of a linear viscoelastic behavior were explained. Finally, the applicability of a time-temperature superposition principle originally developed for polymeric materials was examined using a shift factor. Main results obtained from this study can be summarized as follows : (1) At very small strain amplitude region, vaseline shows a linear viscoelastic behavior independent of the imposed deformation magnitudes. Above a critical strain amplitude $({\gamma}_{0}=0.1{\sim}0.2%)$, however, vaseline exhibits a nonlinear viscoelastic behavior ; indicating that both the storage modulus and dynamic viscosity are sharply decreased with increasing deformation magnitude. (2) In large amplitude oscillatory shear flow fields, an elastic behavior (storage modulus) has a stronger strain amplitude dependence and begins to show a nonlinear behavior at a smaller strain amplitude region than does a viscous behavior (dynamic viscosity). (3) In small amplitude oscillatory shear flow fields, the storage modulus as well as the loss modulus are continuously increased as an increase in angular frequency and an elastic nature is always superior to a viscous behavior over a wide range of angular frequencies. (4) A time-temperature superposition principle can successfully be applicable to vaseline. This finding allows us to estimate the dynamic viscoelastic behavior of vaseline over an extraordinarily extended range (11 decades) of angular frequencies inaccessible from the experimentally measured range (4 decades).

Pure-Zr의 ECAP공정에서 마찰이 재료의 변형거동과 금형에 미치는 영향 (Frictional Effects on the Deformation Behavior of materials and Die during Equal Channel Angular Pressing(ECAP) with Pure-Zr)

  • 권기환;채수원;권숙인;김명호;황선근
    • 한국정밀공학회지
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    • 제18권6호
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    • pp.182-187
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    • 2001
  • Much research efforts have been made on the equal-channel angular pressing(ECAP)that produces ultra-fine grain size materials. Recently many materials have been tested for ECAP process, and in this paper pure-Zirconium is considered due to its applicability to nuclear reactors. Among many process parameters of ECAP, frictional effects on the deformation behavior of materials and on the stress distribution of die have been investigated. The finite element method has been employed in order to investigate this issue, and experiments have also been made to verify the numerical results.

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연속 다단 ECAP 공정을 통한 급속응고 Al-20 wt% Si 합금 분말의 고형화 및 특성 평가 (Consolidation and Mechanical Property of Rapidly Solidified Al-20 wt% Si Alloy Powders by Continuous Equal Channel Multi-Angular Pressing)

  • 윤승채;복천희;서민홍;홍순직;김형섭
    • 한국분말재료학회지
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    • 제15권1호
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    • pp.31-36
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    • 2008
  • In this study, the bottom-up powder metallurgy and the top-down severe plastic deformation (SPD) techniques for manufacturing bulk nanomaterials were combined in order to achieve both full density and grain refinement without grain growth of rapidly solidified Al-20 wt% Si alloy powders during consolidation processing. Continuous equal channel multi-angular processing (C-ECMAP) was proposed to improve low productivity of conventional ECAP, one of the most promising method in SPD. As a powder consolidation method, C-ECMAP was employed. A wide range of experimental studies were carried out for characterizing mechanical properties and microstructures of the ECMAP processed materials. It was found that effective properties of high strength and full density maintaining nanoscale microstructure are achieved. The proposed SPD processing of powder materials can be a good method to achieve fully density and nanostructured materials.

고정도 열변위보정을 위한 주축대의 열적굽힘에 대한 연구 (Research into Head-body Thermal Bending for High-accuracy Thermal Error Compensation)

  • 김태원;하재용;고태조
    • 한국정밀공학회지
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    • 제19권1호
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    • pp.56-64
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    • 2002
  • Machine tools are engineered to give high dimensional accuracy in machining operation. However, errors due to thermal effects degrade dimensional accuracy of machine tools considerably, and many machine tools are equipped with thermal error compensation function. In general, thermal errors can be generated in the angular directions as well as linear directions. Among them, thermal errors in the angular directions contribute a large amount of error components in the presence of offset distance as in the case of Abbe error. Because most of thermal error compensation function is based on a good correlation between temperature change and thermal deformation, angular thermal deformation is often to be the most difficult hurdle for enhancing compensation accuracy. In this regard, this paper investigates the effect of thermal bending to total thermal error and gives how to deal with thermally induced bending effects in thermal error compensation.

마그네슘의 등통로각압축 시 파괴 및 기계적 특성에 미치는 공정온도 효과 (Effect of Equal Channel Angular Pressing Temperature on the Fracture and Mechanical Properties of Magnesium)

  • 윤승채;복천희;곽은정;정영기;김택수;김형섭
    • 소성∙가공
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    • 제17권1호
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    • pp.13-18
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    • 2008
  • Mg and Mg alloys are promising materials for light weight high strength applications. In this paper, grain refinement of pure Mg using severe plastic deformation was tried to enhance the mechanical properties of the hard-to-deform metallic material. The microstructure and the mechanical properties of Mg processed by equal channel angular pressing(ECAP) at various processing temperatures were investigated experimentally. ECAP with channel angle of $90^{\circ}$ and corner angle of $0^{\circ}$ was successful at $300^{\circ}C$ without fracture of the samples during the processing. The hardness of the ECAP processed Mg decreased with increasing ECAP processing temperature. The effect of temperature on the hardness and microstructure of the ECAP processed Mg were explained by the dislocation glide in the basal plane and non-basal slip systems and by the dynamic recrystallization and recovery.

결정 소성학과 강소성 유한요소해석을 연계한 ECAE 공정에서의 변형 집합 조직 발달에 대한 연구 (Prediction of Texture Evolution in Equal Channel Angular Extrusion (ECAE) Using Rate-Independent Crystal Plasticity with Rigid-Plastic Finite Element Method)

  • 김경진;윤정환;양동열
    • 한국정밀공학회지
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    • 제32권11호
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    • pp.937-944
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    • 2015
  • Recently, the change of mechanical properties and microstructural evolution during severe plastic deformation (SPD), such as Equal Channel Angular Extrusion (ECAE), has been the subject of intensive investigation because of the unique physical and mechanical properties of severely deformed materials. In this study, two types of ECAE processes were considered, dies with intersection angles ${\Phi}$ of $90^{\circ}$ and $120^{\circ}$, using experiments and simulations. The decoupled method, in which the rigid-plastic finite element method is incorporated with the rate-independent crystal plasticity model, was applied to predict the texture evolution in commercially pure aluminum during the ECAE processes with $120^{\circ}$ and $90^{\circ}$ dies. The simulated textures were compared with a measured texture via an EBSD OIM analysis. The comparison showed that the simulated textures generally were in good agreement with the experimentally measured texture.

음향재료신호를 이용한 강소성변형된 알루미늄 5052 합금의 탄성계수 측정 (Determination of Elastic Modulus of Equal-Channel-Angular-Pressed Aluminum 5052 Alloy by Acoustic Material Signature)

  • 김정석;박익근;장경영
    • 비파괴검사학회지
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    • 제30권2호
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    • pp.146-154
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    • 2010
  • 알루미늄 5052 합금의 탄성특성에 대한 ECAP 강소성변형과 어닐링효과를 연구하였다. 알루미늄 5052 합금은 용체화 처리 후 ECAP 가공하고 어닐링처리를 수행하였다. 탄성계수는 기존의 인장시험과 나노압입시험을 통해 측정하고 음향현미경의 음향재료신호를 이용하여 시료의 표변에서 탄성계수를 측정하였다. 기존의 시험법으로는 불가능한 소성변형과 열처리에 따른 탄성계수의 변화를 음향재료신호를 이용하여 성공적으로 측정하였고 개개의 결정립에서도 결정방위에 의존하는 탄성계수를 얻었다.

알루미늄 AA 1050 판재구속전단가공 시 불균질 집합조직 형성의 해석 (Analysis on Inhomogeneous Textures Developed in Aluminum AA 1050 Sheets during Continuous Confined Strip Shearing)

  • 이재필;석한길;허무영
    • 소성∙가공
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    • 제13권4호
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    • pp.382-387
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    • 2004
  • The continuous confined strip shearing (CCSS) based on the equal channel angular pressing (ECAP) was modeled by means of a rigid-plastic two-dimensional finite element method (FEM). Parallel to the simulations, samples of AA 1050 sheets were experimentally deformed by CCSS. The CCSS deformation led to the formation of through thickness texture gradients comprising a strong shear texture in the sheet center and weak shear textures in the sheet surfaces. FEM analysis revealed variations in the strain component $\varepsilon_13$ along the sample thickness direction, which gave rise to the evolution of different textures. A high friction between the sample and die surface was responsible for lowering intensities of the shear texture components in thickness layers close to the surfaces.

ECAP한 Al 판재의 판재성형성 (Formability of ECAPed Al Alloy Sheet)

  • ;김인수;이민구;박병현
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2006년도 춘계학술대회 논문집
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    • pp.285-287
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    • 2006
  • Ultra-fine grained and high hardened Al sheet was obtained by Equal channel angular pressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Al alloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP and subsequent heat-treatment condition has been investigated in this study. It was found that the average r-value of the ECAPed and subsequent heat-treated specimen was 1.7 times higher than those of the initial Al sheet. This could be attributed to the various texture formations through the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheet.

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