• Title/Summary/Keyword: initial theory

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Analysis on the Load Carrying Capacity of Steel Bridges Considering Initial Stress (강교의 초기응력을 고려한 내하력 해석)

  • Chang, Kyong-Ho;Kang, Jae-Hoon;Jang, Gab-Chul
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.4 s.14
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    • pp.129-136
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    • 2004
  • Almost the steel bridges are manufactured and constructed by using weld process. The welding is necessary for connecting the flange, web and stiffener of steel bridges. However, residual stress and welding deformation producted by welding is a causes of decreasing the load carrying capacity of steel bridges. therefore, it is need to consider the initial stresses by welding when design the steel bridge. However, the influence of initial stress producted by welding on load carrying capacity of steel bridges is not elucidated. In this paper, the initial stress state on the flange, web and stiffener of steel bridges are clarified by carrying out 3-dimensional non-steady heat conduction analysis and 3-dimensional thermal elastic-plastic analysis. The influence of initial stress by welding on load carrying capacity of steel bridges is clarified by carrying out 3-dimensional elastic-plastic finite element analysis using finite deformation theory.

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Nursing students' initial clinical experience (간호학생의 첫 임상실습 경험)

  • Moon Mi-Sook
    • The Journal of Korean Academic Society of Nursing Education
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    • v.4 no.1
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    • pp.15-27
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    • 1998
  • In order to help students through their initial clinical experience, faculty must understand more fully the moaning of this experience for nursing students. This study was performed to understand and to explain what is the essential structure of nursing students' initial clinical experience. A grounded theory approach was conducted to explore the actual experience of nursing students' first clinical experience. Each of the nursing students' descriptions about their initial clinical experience was analyzed using Strauss & Corbin's method. The results of the study were as follows : From the 172 written descriptions and 7 in-depth individual interviews, 128 concepts were extracted. After identifying the concepts' formulated meaning, they were organized into 29 subcategories and the following 12 categories . burden, encountering difficulties, self-discovery, grasping actuality, acquirement of nurse's nature, special character of experience, special character of relationship, external effect, problem oriented coping, emotional oriented coping, affection for nursing, skeptical view of nursing. Five hypotheses were derived from the analysis. 1) Burden is an obstacle to grasp nursing actuality. 2) Special character of experience and external effect have an effect on grasping nursing actuality, 3) Encouragement, a part of external effects, will increase nursing student's affection for nursing. 4) Affection for nursing through first clinical experience facilitates positive nursing view and scholarly zest. 5) Disappointment with the difference be tween theory and reality will cause the student to take a skeptical view of nursing. It is hoped that the knowledge gained from this qualitative study will enable faculty to enter more fully Into the world of nursing students as they embark on their initial clinical experience.

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Behavior of Tapered Columns with Initial Imperfection (Initial Imperfection을 갖는 변단면 기둥의 거동 해석)

  • 이병구;모정만
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1996.04a
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    • pp.19-26
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    • 1996
  • The main purpose of this paper is to investigate a more accurate behavior analysis of tapered column with initial imperfection. The nonlinear differential equations governing the deflected shapes of the tapered column with initial imperfection are derived by large deflection theory and solved numerically using the Runge-Kutta method and Regula-Falsi method. Three kinds of cross-sectional shape with simply supported end constraint are considered in numerical examples. The load versus displacement curves including the left and right end rotations are presented in figures. The effect of cross-sectional shapes on deflected shape is analyzed, and the deflected shapes of column for several initial imperfections are shown in figure.

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Frequency response of initially deflected nanotubes conveying fluid via a nonlinear NSGT model

  • Farajpour, Ali;Ghayesh, Mergen H.;Farokhi, Hamed
    • Structural Engineering and Mechanics
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    • v.72 no.1
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    • pp.71-81
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    • 2019
  • The objective of this paper is to develop a size-dependent nonlinear model of beams for fluid-conveying nanotubes with an initial deflection. The nonlinear frequency response of the nanotube is analysed via an Euler-Bernoulli model. Size influences on the behaviour of the nanosystem are described utilising the nonlocal strain gradient theory (NSGT). Relative motions at the inner wall of the nanotube is taken into consideration via Beskok-Karniadakis model. Formulating kinetic and elastic energies and then employing Hamilton's approach, the nonlinear motion equations are derived. Furthermore, Galerkin's approach is employed for discretisation, and then a continuation scheme is developed for obtaining numerical results. It is observed that an initial deflection significantly alters the frequency response of NSGT nanotubes conveying fluid. For small initial deflections, a hardening nonlinearity is found whereas a softening-hardening nonlinearity is observed for large initial deflections.

Prediction of Deformation Mechanism and Fracture for an Auto-Part with Advanced High Strength Steel using Solid Element and Damage Theory (연속체요소 및 손상이론을 이용한 고강도강 차량부품의 변형기구와 파단 예측)

  • Kwak, J.H.;Yoon, S.J.;Kim, S.H.;Park, J.K.;Han, H.G.
    • Transactions of Materials Processing
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    • v.26 no.5
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    • pp.293-299
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    • 2017
  • In this paper, finite element stamping analysis was carried out for the front lower arm to examine the applicability of solid element with damage theory to predict shear fracture phenomena induced by sheared edge as well as deformation mechanisms. Mechanical properties related to deformation and damage theory were determined from tensile test. Shear fracture was predicted by normalized Cockcroft-Latham model with initial imposition of the damage value along the sheared edge. Simulation results illustrated that the analysis with solid element and damage theory predicted edge profile, strain distribution, and forming load more accurately than the analysis with shell element. Simulation with solid element can also predict the shear fracture more exactly comparing to analysis with shell element and forming limit curve.

Development and application of Auto-Wind program for automated analysis of wind resource (풍력자원해석 자동화 프로그램 Auto-Wind 개발과 응용)

  • Yoon, Seong-Wook;Jeon, Wan-Ho;Kim, Hyun-Goo
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.191-191
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    • 2010
  • As many researchers want to predict or assess more about wind condition and wind power generation, CFD(Computational Fluid Dynamics) analysis method is very good way to do predict or assess wind condition and power generation. But CFD analysis is needed much knowledge of aerodynamics and physical fluid theory. In this paper, Auto-Wind CFD analysis program will be introduced. User does not need specific knowledge of CFD or fluid theory. This program just needs topographical data and wind data for initial condition. Then all of process is running automatically without any order of user. And this program gives for user to select and set initial condition for advanced solving CFD. At the last procedure of solving, Auto-Wind program shows analysis of topography and wind condition of target area. Moreover, Auto-Wind can predict wind power generation with calculation in the program. This Auto-Wind analysis program will be good tool for many wind power researchers in real field.

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A unified formulation for static behavior of nonlocal curved beams

  • Tufekci, Ekrem;Aya, Serhan A.;Oldac, Olcay
    • Structural Engineering and Mechanics
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    • v.59 no.3
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    • pp.475-502
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    • 2016
  • Nanobeams are widely used as a structural element for nanodevices and nanomachines. The development of nano-sized machines depends on proper understanding of mechanical behavior of these nano-sized beam elements. Small length scales such as lattice spacing between atoms, surface properties, grain size etc. are need to be considered when applying any classical continuum model. In this study, Eringen's nonlocal elasticity theory is incorporated into classical beam model considering the effects of axial extension and the shear deformation to capture unique static behavior of the nanobeams under continuum mechanics theory. The governing differential equations are obtained for curved beams and solved exactly by using the initial value method. Circular uniform beam with concentrated loads are considered. The displacements, slopes and the stress resultants are obtained analytically. A detailed parametric study is conducted to examine the effect of the nonlocal parameter, mechanical loadings, opening angle, boundary conditions, and slenderness ratio on the static behavior of the nanobeam.

Numerical Study on Sheet Metal Forming Analysis Using the One-Step Forming (One-Step Forming을 이용한 박판성형 해석에 관한 연구)

  • Jeong, Dong-Won;Lee, Sang-Je;Kim, Gwang-Hui
    • Journal of Ocean Engineering and Technology
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    • v.13 no.2 s.32
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    • pp.11-17
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    • 1999
  • The objective of this paper is to introduce very fast but still stable solution using finite element procedures, and it has been used in an iterative mode for product design applications. A lot of numerical techniques have been developed to deal with the material, geometric and boundary condition non-linearities occurred in the stamping process. One of them, the One-Step FEM is very efficient and useful tool for a design and trouble-shooting in various stamping processes. In this method, the mathod, the material is assumed to deform directly from the initial flat blank to the final configuration without any intermediate steps. The formulation is based on the deformation theory of plasticity and the upper bound theorem. As a result of the calculations, the initial blank shape is obtained, together with the material flow, strains and thickness distribution in the part.

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