• Title/Summary/Keyword: deformation behavior stability

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Stability Analysis of Unsaturated Soil Slope by Coupled Hydro-mechanical Model Considering Air Flow (공기흐름을 고려한 수리-역학적 연동모델에 의한 불포화 토사사면의 안정해석)

  • Cho, Sung-Eun
    • Journal of the Korean Geotechnical Society
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    • v.32 no.1
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    • pp.19-33
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    • 2016
  • Stability analysis based on the limit equilibrium method combined with the result of infiltration analysis is commonly used to evaluate the effect of rainfall infiltration on the slope stability. Soil is a three-phase mixture composed of solid particle, water and air. Therefore, a fully coupled mixture theories of stress-deformation behavior and the flow of water and air should be used to accurately analyze the process of rainfall infiltration through soil slope. The purpose of this study is to study the effect of interaction of air and water flow on the mechanical stability of slope. In this study, stability analyses based on the coupled hydro-mechanical model of three-phases were conducted for slope of weathered granite soil widespread in Korea. During the process of hydro-mechanical analysis strength reduction technique was applied to evaluate the effect of rainfall infiltration on the slope stability. The results showed an increase of air pressure during infiltration because rain water continuously displaced the air in the unsaturated zone. Such water-air interaction in the pore space of soil affects the stress-deformation behavior of slope. Therefore, the results from the three-phase model showed different behavior from the solid-water model that ignores the transport effect of air in the pores.

Thermal Behavior Analysis of a CNC Lathe (CNC 선반의 열적 거동 해석)

  • 안경기;조동우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.778-783
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    • 1994
  • In operating automated manufacturing system, the long term stability and reliability of NC machine tools become most critical issues. Especially the machining accuracy is dominated by the thermal deformation of machine tools which remains still unsolved and causes troubles in manufacturing operations. Although researches have been carried out on the thermal behavior of a machine tools to minimize or control the thermal deformation of machine tools, the computer models for an analysis of the thermal behacior in machine tools has yet to appear in the open literature. The object of the paper is to present a method of modeling the thermal behavior of a machine tool. The method will make use of finite elements ad be capable of modeling whole machine structures as well as of heat generation processes in the kinematic system components. And temperature distributions and thermal deformations of a CNC lathe are analyzed using the finite element method and are compared with those measured in practice.

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Centrifuge Model Experiments and Numerical Analyses of the Behavior of Excavated Marine Clay Slope (해성점토 굴착사면의 거동에 관한 원심모형실험 및 수치해석)

  • Park, Byung-Soo
    • Journal of Ocean Engineering and Technology
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    • v.20 no.5 s.72
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    • pp.49-56
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    • 2006
  • In this thesis, centrifuge model experiments and numerical analyses were carried out to investigate the behavior of an excavated slope in soft clay ground. Centrifuge model tests were performed with various slopes for the excavated ground, such as 1:1.5 and 1:2. Pore pressuresthe model ground were measured to find their effects on the stability of the excavated slope. These experiments showed that the model with 1:2.5 maintained its stability within a short period of time and failed gradually. Therefore, anexcavated slope of soft soil with this slope might maintain stable conditions within a certain time. The mode1 with a 1:3 slope was observed to maintain a very stable condition, showing insignificant deformation in the ground after being excavated. Numerical analyses with PLAXIS, a commerciallyavailable software implemented with the finite element numerical technique, were performed to find the pore pressure distribution within the ground mass and the deformation of the soil. From the results of numerical analysis, a negative pore pressure was developed after the excavation and thus the stability of the slope was maintained. The safety factor for slope failure was found to decrease with time because of the dissipation of negative pore pressure with time.

Effect of flexure-extension coupling on the elastic instability of a composite laminate plate

  • H. Mataich;A. El Amrani;J. El Mekkaoui;B. El Amrani
    • Structural Engineering and Mechanics
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    • v.90 no.4
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    • pp.391-401
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    • 2024
  • The present study focuses on the effect of extension-bending coupling on the elastic stability (buckling) of laminated composite plates. These plates will be loaded under uni-axial or bi-axial in-plane mechanical loads, especially in the orthotropic or anti-symmetric cross-angle cases. The main objective is to find a limit where we can approximate the elastic stability behavior of angularly crossed anti-symmetric plates by the simple behavior of specially orthotropic plates. The contribution of my present study is to predict the explicit effect of extension-flexion coupling on the elastic stability of this type of panel. Critically, a parametric study is carried out, involving the search for the critical buckling load as a function of deformation mode, aspect ratio, plate anisotropy ratio and finally the study of the effect of lamination angle and number of layers on the contribution of extension-flexure coupling in terms of plate buckling stability. We use first-order shear deformation theory (FSDT) with a correction factor of 5/6. Simply supported conditions along the four boundaries are adopted where we can develop closed-form analytical solutions obtained by a Navier development.

Behavior of Tunnel Face Reinforced with Horizontal Pipes (수평보강재로 보강된 터널 막장의 거동)

  • 유충식;신현강
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.185-192
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    • 1999
  • This paper presents the results of a parametric study on the behavior of tunnel face reinforced with horizontal pipes. A three-dimensional finite element model was adopted in this study to capture the three-dimensional nature of tunnel face behavior under various boundary conditions. A parametric study was peformed on a wide range of boundary conditions with emphasis on the effect of reinforcing layouts on the deformation behavior of tunnel face. The results of analysis such as tunnel face deformation behavior under various conditions were thoroughly analyzed, and a database for the behavior of tunnel face under different reinforcing conditions was established for future development of a semi-empirical design/analysis method for the tunnel face reinforcing technique. The results indicated that there exits an optimum reinforcing layout for a given tunnel condition, which must be selected with due consideration of tunnel geometry and ground condition.

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Press Formability of Austenitic AISI304 Stainless Steel (오스테나이트계 AISI304 스테인레스강판의 프레스 성형특성)

  • Nam, J.B.;Ryoo, D.Y.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.3 no.1
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    • pp.38-50
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    • 1994
  • Fundamental deformation mechanism and plastic behavior of AISI304 austenitic stainless steel were investigated to evaluate press formability. Local and uniform deformation capacity of AISI304 steel were compared to those of ferritic AISI430 steel and Al killed low carbon steel. Nine kinds of austenitic stainless steels having different austenite stabilities were made in laboratory scale to examine the transformation behavior in various deformation mode and variation of mechanical properties. Deformation path and strain distributions along edge corner of commercial sink die were illustrated and effect of austenite stability on press forming of sink die was clarified with experiments using square cup drawing tools.

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EFFECT OF Ni CONTENT ON THE AUSTENITE STABILITY AND MECHANICAL PROPERTIES OF NANOCRYSTALLINE Fe-Ni ALLOY FABRICATED BY SPARK PLASMA SINTERING

  • D. PARK;S.-J. OH;I.-J. SHON;S.-J. LEE
    • Archives of Metallurgy and Materials
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    • v.63 no.3
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    • pp.1477-1480
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    • 2018
  • The mechanical behavior and the change of retained austenite of nanocrystalline Fe-Ni alloy have been investigated by considering the effect of various Ni addition amount. The nanocrystalline Fe-Ni alloy samples were rapidly fabricated by spark plasma sintering (SPS). The SPS is a well-known effective sintering process with an extremely short densification time not only to reach a theoretical density value but also to prevent a grain growth, which could result in a nanocrystalline structures. The effect of Ni addition on the compressive stress-strain behavior was analyzed. The variation of the volume fraction of retained austenite due to deformation was quantitatively measured by means of x-ray diffraction and microscope analyses. The strain-induced martensite transformation was observed in Fe-Ni alloy. The different amount of Ni influenced the rate of the strain-induced martensite transformation kinetics and resulted in the change of the work hardening during the compressive deformation.

High Temperature Compressive Deformation Behavior of the Bulk Metallic Glass Zr-Ti-Cu-Ni-Be Alloy (벌크 비정질 Zr-Ti-Cu-Ni-Be 합금의 고온 압축 변형 특성)

  • 이광석;하태권;안상호;장영원
    • Transactions of Materials Processing
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    • v.10 no.7
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    • pp.565-572
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    • 2001
  • It is well known that a multicomponent $Zr_{4l.2}Ti_{13.8}Cu_{12.5}Ni_{10}Be_{22.5}$ bulk metallic glass alloy shows good bulk glass forming ability due to its high resistance to crystallization in the undercooled liquid state. DSC and XRD have been performed to confirm the amorphous structure of the master alloy. To investigate the mechanical properties and deformation behavior of the bulk metallic $Zr_{4l.2}Ti_{13.8}Cu_{12.5}Ni_{10}Be_{22.5}$ alloy, a series of compression tests has been carried out at the temperatures ranging from $351^{\circ}C$ to $461^{\circ}C$at the various initial strain rates from $2{\times}10^4s^1$ to $2{\times}10^2s^1$. Three types of nominal stress-strain curves have been identified such as linear stress-strain relationship meaning fracture at maximum stress, plastic deformation including stress overshoot and steady-state flow, plastic deformation without stress overshoot depending on the strain rate and test temperature. Also DSC analysis for the compressed specimens was carried out to investigate the change of structure, thermal stability and crystallization behavior for the various test conditions.

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On the stability of isotropic and composite thick plates

  • Mahmoud, S.R.;Tounsi, Abdelouahed
    • Steel and Composite Structures
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    • v.33 no.4
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    • pp.551-568
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    • 2019
  • This proposed project presents the bi-axial and uni-axial stability behavior of laminated composite plates based on an original three variable "refined" plate theory. The important "novelty" of this theory is that besides the inclusion of a cubic distribution of transverse shear deformations across the thickness of the structure, it treats only three variables such as conventional plate theory (CPT) instead five as in the well-known theory of "first shear deformation" (FSDT) and theory of "higher order shear deformation" (HSDT). A "shear correction coefficient" is therefore not employed in the current formulation. The computed results are compared with those of the CPT, FSDT and exact 3D elasticity theory. Good agreement is demonstrated and proved for the present results with those of "HSDT" and elasticity theory.

Experimental and Measurement Methods for the Small-Scale Model Testing of Lateral and Torsional Stability

  • Lee, Jong-Han;Park, Yong Myung;Jung, Chi-Young;Kim, Jae-Bong
    • International Journal of Concrete Structures and Materials
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    • v.11 no.2
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    • pp.377-389
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    • 2017
  • Tests of the lateral and torsional stability are quite sensitive to the experimental conditions, such as support conditions and loading system. Controlling all of these conditions in a full-size test is a very challenging task. Therefore, in this paper, an experimental measurement method that can control the experimental conditions using a small-scale model was proposed to evaluate the lateral and torsional stability of beams. For this, a loading system was provided to maintain the vertical direction of the load applied to the beam, and a support frame was produced to satisfy the in-plane and out-of-plane support conditions. The experimental method using a small-scale model was applied successively to the lateral and torsional behavior and stability of I-shaped beams. The proposed experimental methods, which effectively accommodate the changes in the geometry and length of the beam, could contribute to further experimental studies regarding the lateral and torsional stability of flexural members.