• Title/Summary/Keyword: deformation condition

Search Result 1,367, Processing Time 0.025 seconds

A Study on Stable-Unstable Behavior in Concrete (콘크리트의 안정-불안정 거동에 관한 연구)

  • 송하원;전재홍;변근주
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1996.10a
    • /
    • pp.459-465
    • /
    • 1996
  • This paper is about unstable behavior in concrete during the localized deformation and the crack growths in concrete. By modeling the strain localization phenomenon of concrete, the stability condition of the localization is obtained and analyzed. And the stability and bifurcation condition of crack growths in two parallel cracks under different loading conditions are derived and discussed.

  • PDF

Study on the Sheet Rolling by a Rigid-Plastic Finite Element Method Considering Large Deformation Formulation (강소성 대변형 유한요소법을 이용한 판재 압연연구)

  • 김동원;홍성인
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.15 no.1
    • /
    • pp.145-153
    • /
    • 1991
  • A numerical simulation of the nonsteady state rolling process in the plane strain condition is presented in the basis of the rigid-plastic finite element method by considering large deformation. In order to apply the large deformation theory to the numerical method for sheet rolling problems, constitutive equation relating 2nd-Piola Kirchhoff stress and Lagrangian strain which reflect geometrical nonlinearity is used. To confirm the validity of the developed algorithm, the analysis of the neutral flow region, roll separating force, torque, pressure and stress/strain distributions on the workpiece is conducted from the bite of the material until the steady state is reached. The computed results of the roll force and torque in the present finite element analysis are lower than those corresponding to small strain theory. The pressure distribution at the work piece-roll interface is found to show the typical 'friction hill' type only. The peak value in near the neutral region, however, is good agrements with the existing results. the neutral region, however, is good agrements with the existing results. The frictional force at the roll interface provide detailed information about the neutral point where the shear forces change direction. In addition, the analysis also includes the effect and influence of material condition, strip thickness, work roll diameter, as well as roll speed and lubricant on each deformation process.

Deformation of Flush Door Depending on Core Construction Under the Change of Environmental Condition (환경 노출 조건 하에서 심재구성에 따른 플러쉬문의 변형)

  • Jang, Sang Sik
    • Journal of the Korean Wood Science and Technology
    • /
    • v.31 no.2
    • /
    • pp.38-44
    • /
    • 2003
  • This study was carried out to evaluate the feasibility of using HDF as surface panels as well as core materials for flush door manufacturing. Six core constructions were developed and applied to manufacture door specimens and conventional skin door specimen was also manufactured for comparison. Door specimens were tested under changing interior environmental condition for 3~4 months during winter and summer seasons. During the test period, deformation of doors were measured weekly, and temperature and relative humidity of testing area were also recorded. From this study, it was concluded that HDF can be used to manufacture quality flush doors and core construction developed in this study showed good quality compared to conventional skin door. Deformation of doors increased as temperature and relative humidity of the surrounding environment increased. Flush doors generally showed less deformation than skin doors, and evaluated to be stable and good quality when compared to skin door.

High Temperature Deformation Behavior and Formability of Zr-Cu-Al-Ni Bulk Metallic Glass (Zr 계 비정질 합금의 고온 변형거동과 성형성 예측)

  • Jun, H.J.;Lee, K.S.;Chang, Y.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2007.05a
    • /
    • pp.123-126
    • /
    • 2007
  • Deformation behavior of $Zr_{55}Cu_{30}Al_{10}Ni_5$ (at. %) bulk metallic glass (BMG) fabricated by suction casting method has been investigated at elevated temperatures in this study. The BMG was first verified to have an amorphous structure thru X-ray diffraction (XRD) and differential scanning calorimetry (DSC). A series of compression tests has consequently been performed in supercooled liquid temperature region to investigate the high temperature deformation behavior. A transition from Newtonian to non-Newtonian flow appeared to take place depending upon both the strain rate and test temperature. A processing map based on a dynamic materials model has been constructed to estimate a feasible forming condition for this BMG alloy.

  • PDF

Residual Stress Analysis of Hot Rolled Strip (열연 강판의 잔류 응력 해석)

  • 구진모;김홍준;이재권;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2003.05a
    • /
    • pp.172-175
    • /
    • 2003
  • Run-Out-Table is the region between EDT and CT. Hot killed strip is cooled by air and water in ROT. In this procedure, phase transformation and shape deformation occur due to temperature drop. Because of un-ideal cooling condition, deformation of strip and non-uniform phase distribution come into existence. This phenomenon affects the strip property and lead th the existence of residual stress. And it exerts effects on the Coiling process, Coil Cooling process, and Un-coiling process. Through these process, the residual stresses of strip are more larger and unbalance of these stresses become more severe. Finite element (FE) based models for the analysises of non-steady state heat transfer and elastoplastic deformation are described in this investigation. The analysises of thermodynamics and phase transformation kinetics are suggested also. Using the ROT simulation result coiling process and coil cooling process simulations are carried out.

  • PDF

The Effects of Heat Treatment on Cyclic Deformation of Ni-Ti Shape Memory Alloy (Ti-Ni 형상기억합금의 반복 변형 거동에 미치는 열처리의 영향)

  • 박영철;조용배;오세욱
    • Journal of Ocean Engineering and Technology
    • /
    • v.8 no.1
    • /
    • pp.154-164
    • /
    • 1994
  • In this paper, fatigue testing was carried out under the change of aging time(0.5,1.5.10hrs) by electric heating method which is one of the useful method in the application of Robot's actuator. Fatigue degradation behaviors such as cyclic deformation property, amount of deformation, decrease in recovery and variation of transformation temperature for each specimen were examined closely, and the effect of aging time condition was studied on their fatigue degradation behaviors.

  • PDF

Average Flow Model with Elastic Deformation for CMP (화학적 기계 연마를 위한 탄성변형을 고려한 평균유동모델)

  • Kim Tae-Wan;Lee Sang-Don;Cho Yong-Joo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 2004.11a
    • /
    • pp.331-338
    • /
    • 2004
  • We present a three-dimensional average flow model considering elastic deformation of pad asperities for chemical mechanical planarization. To consider the contact deformation of pad asperities in the calculation of the flow factor, three-dimensional contact analysis of a semi-infinite solid based on the use of influence functions is conducted from computer generated three dimensional roughness data. The average Reynolds equation and the boundary condition of both force and momentum balance are used to investigate the effect of pad roughness and external pressure conditions on film thickness and wafer position angle.

  • PDF

The buckling of piezoelectric plates on pasternak elastic foundation using higher-order shear deformation plate theories

  • Ellali, Mokhtar;Amara, Khaled;Bouazza, Mokhtar;Bourada, Fouad
    • Smart Structures and Systems
    • /
    • v.21 no.1
    • /
    • pp.113-122
    • /
    • 2018
  • In this article, an exact analytical solution for mechanical buckling analysis of magnetoelectroelastic plate resting on pasternak foundation is investigated based on the third-order shear deformation plate theory. The in-plane electric and magnetic fields can be ignored for plates. According to Maxwell equation and magnetoelectric boundary condition, the variation of electric and magnetic potentials along the thickness direction of the plate is determined. The von Karman model is exploited to capture the effect of nonlinearity. Navier's approach has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical results reveal the effects of (i) lateral load, (ii) electric load, (iii) magnetic load and (iv) higher order shear deformation theory on the critical buckling load have been investigated. These results must be the analysis of intelligent structures constructed from magnetoelectroelastic materials.

Optimum forming design of A350 LF2 alloy using the deformation processing map (변형 공정지도를 활용한 A350 LF2 합금의 최적성형 조건설계에 대한 연구)

  • Jung, E.J.;Yeom, J.T.;Kim, J.H.;Lee, D.G.;Pak, N.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2006.05a
    • /
    • pp.168-171
    • /
    • 2006
  • Hot deformation behavior of A350 LF2 alloy was characterized by compression tests in the temperature range of 800-$1250^{\circ}C$ and the strain rate range of $0.001-10s^{-1}$. The microstructural evolution during hot compression was investigated and deformation mechanisms were analyzed by constructing processing map. Processing maps were generated using the dynamic material model (DMM). The combination of dynamic material model and Ziegler's instability criterion was applied to predict an optimum condition and unstable regions for hot forming.

  • PDF

Influence of Stress-strain on the Microstructural Change in the Metallic Glass and Metallic Glass Matrix Composite

  • Kim, Song-Yi;Lee, A-Young;Oh, Hye-Ryung;Lee, Min-Ha
    • Applied Microscopy
    • /
    • v.45 no.2
    • /
    • pp.44-51
    • /
    • 2015
  • At room temperature, metallic glasses deform inhomogeneously by strain localization into narrow bands as a result of yielding due to an external force. When shear bands are generated during deformation, often nanocrystals form at the shear bands. Experimental results on the deformation of bulk metallic glass in the current study suggest that the occurrence of nanocrystallization at a shear band implies the loading condition that induces deformation is more triaxial in nature than uniaxial. Under a compressive stress state, the geometrical constraint strain imposed by the stress triaxiality plays a crucial role in the deformation-induced nanocrystallization at the shear bands.