• 제목/요약/키워드: Relative Deformation

검색결과 450건 처리시간 0.025초

Pure-Zirconium의 ECAP 공정에서의 금형의 교차각과 만곡각에 따른 재료의 변형거동해석 (Analysis of Deformation Behavior due to Die Angles during Equal Channel Angular Pressing (ECAP) with Pure-Zirconium)

  • 권기환;채수인;권숙인;김명호;황선근
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.747-753
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    • 2000
  • There has been a number of investigations in recent years reporting the results obtained on the structure and properties of metals deformed to severe plastic deformation (SPD). Being deformed to SPD, ultra-fine grains (UFG) are usually formed, and UFG structure exhibits fundamental differences in original physical properties. One method often used to obtain SPD is equal channel angular pressing (ECAP). In order for this technique to be exploited, it is important to understand the deformation behavior during the ECAP processing and relationship to the configuration of die. The finite element method (FEM) has been used to investigate this issue. It has been found that the plastic deformation is sensitive to the channel angle and material properties and is not uniform across the width of the specimen and the pressing load is relative to deformation during the ECAP processing.

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Effect of membrane deformation on performance of vacuum assisted air gap membrane distillation (V-AGMD)

  • Kim, Yusik;Choi, Jihyeok;Choi, Yongjun;Lee, Sangho
    • Membrane and Water Treatment
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    • 제13권1호
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    • pp.51-62
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    • 2022
  • Vacuum-assisted air gap membrane distillation (V-AGMD) has the potential to achieve higher flux and productivity than conventional air gap membrane distillation (AGMD). Nevertheless, there is not much information on technical aspects of V-AGMD operation. Accordingly, this study aims to analyze the effect of membrane deformation on flux in V-AGMD operation. Experiments were carried out using a bench-scale V-AGMD system. Statistical models were applied to understand the flux behaviors. Statistical models based on MLR, GNN, and MLFNN techniques were developed to describe the experimental data. Results showed that the flux increased by up to 4 times with the application of vacuum in V-AGMD compared with conventional AGMD. The flux in both AGMD and V-AGMD is affected by the difference between the air gap pressure and the saturation pressure of water vapor, but their dependences were different. In V-AGMD, the membranes were found to be deformed due to the vacuum pressure because they were not fully supported by the spacer. As a result, the deformation reduced the effective air gap width. Nevertheless, the rejection and LEP were not changed even if the deformation occurred. The flux behaviors in V-AGMD were successfully interpreted by the GNN and MLFNN models. According to the model calculations, the relative impact of the membrane deformation ranges from 10.3% to 16.1%.

상변태를 고려한 베어링의 열처리 변형 해석 (Heat Treatment Deformation Analysis of Bearing Considering Phase Transformation)

  • 이승표;이석재;김태범;조균택
    • 열처리공학회지
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    • 제36권6호
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    • pp.351-358
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    • 2023
  • Bearings are mechanical components that support loads and transmit rotation. The inner and outer rings come into contact with the rotating mechanism, requiring a very high level of hardness. To meet this requirement, heat treatment is commonly performed. The heat treatment process inherently involves thermal deformation. Particularly in the case of large bearings, significant deformation relative to the bearing's shape can occur, making accurate deformation prediction during heat treatment essential. However, predicting deformation in heat treatment is challenging due to the simultaneous consideration of phase transformation, heat transfer, and bearing deformation. In this study, an analysis of heat treatment-induced deformation in bearings was conducted, taking phase transformation into account. The thermal and mechanical properties were calculated based on the chemical composition of the bearing material. This information was then used to perform a deformation-heat transfer-phase transformation analysis. To validate the reliability of the analysis, experiments were conducted under the same conditions. When comparing the analysis and experimental results, differences in deformation were observed. These differences were attributed to variations in phase transformation conditions between the analysis and experiments. Consequently, it is anticipated that supplementing these results will enable the prediction of deformation while considering phase transformation conditions in bearings.

새만금지역 해상에 퇴적된 사질토의 변형 및 전단강도 특성 (Characteristics of Deformation and Shear Strength of a Sandy Soil Deposited on the SAEMANKEUM Sea)

  • 이강일;주재우;이진수;최종표
    • 한국지반신소재학회논문집
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    • 제9권3호
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    • pp.29-37
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    • 2010
  • 본 연구는 육상과 접해있는 해상에 퇴적된 입자가 매우 균등한 실트섞인 세립질 모래지반의 공학적인 특성을 평가하기 위하여 새만금지역에서 시료를 채취하였다. 채취한 시료에 대하여 상대밀도 시험을 통해 최소 및 최대밀도시험을 하였으며 상대밀도별 사질토의 변형특성과 전단특성을 평가하기 위하여 로우셀압밀시험 및 비배수 삼축압축시험을 실시하였다. 실험결과 상대밀도에 따라서 약간씩 차이는 있지만 새만금지역 해상사질토의 최대 압축 가능한 간극비는 0.88정도이며, 최대 다짐 가능한 상대밀도는 약 71%정도로 평가 되었다. 또한 내부마찰각은 상대밀도의 증가에 따라서 선형적으로 증가하는 양상을 보였으며 기 연구된 군장항에 퇴적된 사질토의 특성과 매우 유사한 전단거동을 보였다.

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Effect of relative density on the shear behaviour of granulated coal ash

  • Yoshimoto, Norimasa;Wu, Yang;Hyodo, Masayuki;Nakata, Yukio
    • Geomechanics and Engineering
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    • 제10권2호
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    • pp.207-224
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    • 2016
  • Granulated coal ash (GCA), a mixture of the by-product from milling processes with a small amount of cement added, has recently come to be used as a new form of geomaterial. The shear strength and deformation behaviours of GCA are greatly determined by its relative density or void ratio. A series of drained triaxial compression tests were performed on cylindrical specimens of GCA at confining pressures of between 50 kPa and 400 kPa at initial relative densities of 50%, 70% and 80%. Experimental results show that a rise in relative density increases the peak shear strength and intensifies the dilation behaviour. The initial tangent modulus and secant modulus of the stress-strain curve increase with increasing initial relative density, whereas the axial and volumetric strains at failure decrease with level of initial relative density. The stress-dilatancy relationships of GCA at different relative densities and confining pressures display similar tendency. The dilatancy behaviour of GCA is modelled by the Nova rule and the material property N in Nova rule of GCA is much larger than that of natural sand.

DIGITAL HOMOLOGY GROUPS OF DIGITAL WEDGE SUMS

  • Kang, Jeang Min;Han, Sang-Eon
    • 호남수학학술지
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    • 제38권4호
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    • pp.819-831
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    • 2016
  • The present paper investigates some properties of the digital homology in [1, 4, 5] and points out some unclearness of the definition of a digital homology and further, suggests a suitable form of a digital homology. Finally, we calculate a digital homology group and a relative digital homology group of some digital wedge sums. Finally, the paper corrects some errors in [6]. In the present paper all digital images (X, k) are assumed to be non-empty and k-connected.

Damage constitutive model of brittle rock considering the compaction of crack

  • Gu, Qingheng;Ning, Jianguo;Tan, Yunliang;Liu, Xuesheng;Ma, Qing;Xu, Qiang
    • Geomechanics and Engineering
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    • 제15권5호
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    • pp.1081-1089
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    • 2018
  • The deformation and strength of brittle rocks are significantly influenced by the crack closure behavior. The relationship between the strength and deformation of rocks under uniaxial loading is the foundation for design and assessment of such scenarios. The concept of relative crack closure strain was proposed to describe the influence of the crack closure behavior on the deformation and strength of rocks. Considering the crack compaction effect, a new damage constitutive model was developed based on accumulated AE counts. First, a damage variable based on the accumulated AE counts was introduced, and the damage evolution equations for the four types of brittle rocks were then derived. Second, a compaction coefficient was proposed to describe the compaction degree and a correction factor was proposed to correct the error in the effective elastic modulus instead of the elastic modulus of the rock without new damage. Finally, the compaction coefficient and correction factor were used to modify the damage constitutive model obtained using the Lemaitre strain equivalence hypothesis. The fitted results of the models were then compared with the experimental data. The results showed that the uniaxial compressive strength and effective elastic modulus decrease with an increase in the relative crack closure strain. The values of the damage variables increase exponentially with strains. The modified damage constitutive equation can be used to more accurately describe the compressive deformation (particularly the compaction stage) of the four types of brittle rocks, with a coefficient of determination greater than 0.9.

Bending Creep Property of Cross-Laminated Woods Made With Six Domestic Species

  • Byeon, Jin-Woong;Kim, Tae-Ho;Yang, Jae-Kyung;Byeon, ee-Seop;Park, Han-Min
    • Journal of the Korean Wood Science and Technology
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    • 제45권6호
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    • pp.689-702
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    • 2017
  • In this study, with the view to using effectively small and medium diameter Korean domestic woods as structural materials, cross-laminated woods were manufactured by using six species of Korean domestic softwoods and hardwoods, and bending creep properties were investigated for each species. The creep curves showed the shape of the exponential function plot, and the creep curves after 1 hour were able to estimate by fitting it to the power law. The initial and creep compliances of cross-laminated woods showed the higher values in wood species with a low density than in that with a high density. And by cross-laminating, the initial and creep compliances perpendicular to the grain considerably decreased, the extent of the decrease was found to be greater in creep deformation than in initial deformation. The creep anisotropies of cross-laminated woods were considerably decreased by cross-laminating. The relative creep of $C_{\bot}$ type composed of perpendicular-direction lamina in the faces decreased 0.59 - 0.64 times compared to that of $P_{\bot}$ type composed of perpendicular-direction laminae in all layers, and that for $C_{\parallel}$ type composed of parallel-direction laminae in the faces increased 1.5 - 1.6 times compared to that of $P_{\parallel}$ type composed of parallel-direction laminae in all layers.

원형공을 갖는 암석의 압축강도 및 변형거동에 미치는 절리의 영향 (The influence of joints on compressive strength and deformation behavior of rock with a circular hole.)

  • 조의권;김일중;김기주;김영석
    • 터널과지하공간
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    • 제7권2호
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    • pp.108-115
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    • 1997
  • Uniaxial and biaxial compressive tests were conducted on limestone specimens containing artificial joints and a circular hole to investigate the influence of inclination and number of joints on compressive strength and deformation behavior of rock with a circular hole. Under uniaxial and biaxial compressive condition, the inclination of joints showing the maximum and minimum strength were 0$^{\circ}$ and 30$^{\circ}$ respectively, which was independent of the number of joints. Under uniaxial compressive condition, relative maximum strength of rock with n=1 and 3 to intact rock with a circular hole were 12.5%~82.8% and 11.4~62.5% respectively, and under biaxial compressive condition, 18.2~91.0% and 17.0~87.5% respectively. The influence of the number of joints on the decrease of compressive strength was greater under uniaxial than under biaxial compressive condition. Under uniaxial and biaxial compressive condition, axial and lateral deformations of rock showed the least values where $\alpha$=30$^{\circ}$. Under uniaxial compressive condition, axial and lateral deformation at maximum strength of rock have the increasing tendency with increase the number of joints. But they have the decreasing tendency under biaxial compressive condition. Under uniaxial and biaxial compressive conditions, axial deformation of circular hole was greater than lateral deformation without respect to the number of joints and the inclination of joints.

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Organ Shape Modeling Based on the Laplacian Deformation Framework for Surface-Based Morphometry Studies

  • Kim, Jae-Il;Park, Jin-Ah
    • Journal of Computing Science and Engineering
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    • 제6권3호
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    • pp.219-226
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    • 2012
  • Recently, shape analysis of human organs has achieved much attention, owing to its potential to localize structural abnormalities. For a group-wise shape analysis, it is important to accurately restore the shape of a target structure in each subject and to build the inter-subject shape correspondences. To accomplish this, we propose a shape modeling method based on the Laplacian deformation framework. We deform a template model of a target structure in the segmented images while restoring subject-specific shape features by using Laplacian surface representation. In order to build the inter-subject shape correspondences, we implemented the progressive weighting scheme for adaptively controlling the rigidity parameter of the deformable model. This weighting scheme helps to preserve the relative distance between each point in the template model as much as possible during model deformation. This area-preserving deformation allows each point of the template model to be located at an anatomically consistent position in the target structure. Another advantage of our method is its application to human organs of non-spherical topology. We present the experiments for evaluating the robustness of shape modeling against large variations in shape and size with the synthetic sets of the second cervical vertebrae (C2), which has a complex shape with holes.