• Title, Summary, Keyword: Deformation Behavior

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Effects by Applying Mode of Single Overload on Propagation Behavior of Fatigue Crack (단일과대하중의 작용모드가 피로균열의 전파거동에 미치는 영향)

  • 송삼홍;이정무
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.109-116
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    • 2004
  • In this study, when variable-amplitude load with various applying mode acts on the pre-crack tip, we examined how fatigue cracks behave. Hence aspects of the deformation caused by changing the applying mode of single overload and propagation behavior of fatigue crack were experimentally examined: What kinds of the deformation would be formed at pre-crack and its tip\ulcorner What aspects of the residual plastic deformation field would be formed in front of a crack\ulcorner How aspects of the plastic zone could be evaluated\ulcorner As applying mode of single overloading changes, the deformation caused by tensile and shear loading variously showed in each applying mode. The different aspects of deformation make influence on propagation behavior of cracks under constant-amplitude fatigue loading after overloading with various modes. We tried to examine the relationship between aspects of deformation and fatigue behavior by comparing the observed deformation at crack and crack propagation behavior obtained from fatigue tests.

Experimental study on the deformation characteristics of RC beam-column subassemblages

  • Guo, Zixiong;Yang, Yong
    • Structural Engineering and Mechanics
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    • v.21 no.4
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    • pp.393-406
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    • 2005
  • Cyclic loading tests were carried out on six half-scale reinforced concrete beam-column subassemblages designed to the current Chinese Seismic Design Code for Buildings. The deformation behavior and restoring force characteristics of the subassemblages were studied. Emphasis was directed on their seismic behavior and deformation components. Based on test data and a simplified analysis model of the global and local deformation, the contribution of the deformation components due to beam flexure, column flexure, joint shear, and slippage of longitudinal reinforcement in the joint to the global deformation of subassemblages at different displacement amplitudes of cyclic loading was investigated.

A 12-year long-term study on the external deformation behavior of Geosynthetic Reinforced Soil (GRS) walls

  • Won, Myoung-Soo;Lee, O-Hyeon;Kim, You-Seong;Choi, Se-Kyung
    • Geomechanics and Engineering
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    • v.10 no.5
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    • pp.565-575
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    • 2016
  • Geosynthetics reinforced soil (GRS) walls constructed on weak grounds may change in both the horizontal earth pressure and deformation on wall facing. However, only few studies were done in the literature to measure and analyze the horizontal external deformation behavior of GRS walls constructed on soft grounds for a long period of time. The present study describes the external deformation behavior of GRS walls observed for 12-year long-term performance. The horizontal deformation of the geosynthetics-wrapped-facing GRS walls shows a passive behavior along one third of the wall height, from top going downwards, and active behavior for the rest of the wall height. Even if the geogrid and nonwoven geotextiles are exposed directly to sunlight and rainfalls in a span of 12 years, they have functioned well as wall facing. Therefore, the geosynthetic reinforcement material is strong enough to resist ultraviolet rays.

The Effect of Plastic Strain on the Superplastic Deformation Behavior (초소성변형특성에 미치는 소성변형랴의 영향)

  • 권용남;장영원
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.291-293
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    • 1997
  • The effect of strain accumulation on the superplastic deformation behavior has been investigated through a series of load relaxation tests. The experimental results were analyzed using the recently proposed inelastic constitutive theory. The superplastic deformation of fine grained materials is confirmed to consist of grain boundary sliding and accommodating grain matrix deformation. However the flow behavior is changed with the plastic strain. It is believed that the microstructural changes such as grain growth and cavitation affect the superplastic deformation behaviors.

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Effects of Nitrogen on Deformation Behavior of Duplex Stainless Steel (이상 스테인레스강의 변형거동에 미치는 질소의 영향)

  • 이형직;장영원
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.49-52
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    • 2003
  • The effects of nitrogen on the deformation behavior of duplex stainless steel have been studied The variation of strength was correlated with the characteristic microstructures. Analysis based on Hall-Petch relation confirmed that nitrogen enhances phase-boundary strengthening effect. The evolution of dislocation structure, slip traces, and misorientation distribution during deformation were also characterized to elucidate the effect of nitrogen on inelastic deformation mechanism.

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Fracture Behavior of AZ31-xCa (x=0, 0.7, 2.0 wt.%) Extrudes during Compression (AZ31-xCa (x=0, 0.7, 2.0 wt.%) 압출재의 압축변형시 파괴거동)

  • Kang, Na Eun;Yim, Chang Dong;You, Bong Sun;Park, Ik Min
    • Korean Journal of Metals and Materials
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    • v.48 no.1
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    • pp.85-89
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    • 2010
  • The plastic deformation behavior of magnesium alloy is affected simultaneously by deformation temperature and strain rate under warm and/or hot working conditions. The soundness of deformation of AZ31-xCa (x=0. 0.7, 2.0 wt.%) extrudes during compression was strongly affected by processing variables including deformation temperature, strain rate. compression-loading direction, which was related to the activation of available deformation systems. The deformation behavior of AZ31-xCa extrudes was also affected by Ca content, which was related to the change of the sort and fraction of second phase. The complex effects of deformation temperature and strain rate on the deformation behavior of AZ31-xCa extrudes during compression under various conditions could be successfully described by Zener-Hollomon parameter.

Effect of Orientation on Plastic Deformation Behavior of Yttria Stabilized Zirconia Single Crystal

  • Cheong, Deock-Soo;Lee, Jeon-Kook
    • Korean Journal of Materials Research
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    • v.19 no.12
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    • pp.674-679
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    • 2009
  • Yttria stabilized zirconia single crystals show plastic deformation at high temperatures by activating dislocations. The plastic deformation is highly dependent on crystallographic orientation. When the samples were deformed at different orientations, stress-strain curves changed by operating different slip systems. The strength of samples was also highly dependent on crystallographic orientation, i.e., samples without yield drop showed higher strength than that of samples exhibiting yield drop. The slip systems in the sample deformed along <112>, <111> and <001> agreed with the theoretical values of the plastic deformation, following Schmid's Law. Dislocations play a major role in the plastic deformation of this crystal. At the early stages of plastic deformation, all samples exhibited dislocation dipoles and, in the later stages, dislocation interactions occurred by forming nodes, tangles and networks. In this study, three different orientations, [11-2], [111] and [001] were employed to explain the plastic deformation behavior. A microstructural analysis was performed to elucidate the mechanism of the plastic behavior of this crystal.

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.

Hot Deformation Behavior of Presintered Steel Powder Preforms (예비소결된 철계분말 preform의 고온변형거동)

  • Lee, Gang-Ryul;Seo, Sang-Gi
    • 한국기계연구소 소보
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    • pp.53-60
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    • 1989
  • Hot upsetting experiments were carried out on presintered steel powder preforms in the temperature range 700- $950^{\circ}C$ to examine the hot deformation behavior. Following conclusions were drawn on the basis of the present study. -The flow stress during hot deformation is directly related to $\alpha$- $\gamma$ phase trasformation - The flow stress of ferrite is lower than that of austenite in the moderate temperature range 800- $900^{\circ}C$ for most alloys used in the present study - Major restoration behavior during hot deformation in the ferrite range is dynamic recovery.

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