• Title/Summary/Keyword: virtual work method

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A Cooling Method which Reduces the Tangential Tensile Stresses on a Work Roll Surface during Hot Slab Rolling (열연 슬라브 압연에서 워크롤 표면 원주방향 인장응력 감소를 위한 냉각 방법)

  • Na, D.H.;Lee, Y.
    • Transactions of Materials Processing
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    • v.21 no.1
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    • pp.58-66
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    • 2012
  • The work roll surface temperature rises and falls repetitively during hot slab rolling because the work roll surface is cooled continuously by water. This study focused on Std. No. 7 to determine a cooling method which significantly reduces the tangential tensile stresses on the work roll surface of the hot slab mill at Hyundai Steel Co. in Korea. A series of finite element analyses were performed to compute the temperature distribution and the tensile stresses in the circumferential direction of the work roll. The virtual slab model was used to reduce the run time considerably by assigning a high temperature to the virtual slab. Except for the heat generated by plastic deformation, this is equivalent to the hot rolling condition that a high temperature slab (material) would experience when in contact with the work rolls. Results showed that when the virtual slab model was coupled with FE analysis, the run time was found to be reduced from 2000 hours to 70 hours. When the work roll surface cooled with a certain on-off patter of water spray, the magnitude of the tangential stresses on the work rolls were decreased by 54.1%, in comparison with those cooled by continuous water spraying. Savings of up to 83.3% in water usage are possible if the proposed water cooling method is adopted.

Analysis of Anisotropic Structures under Multiphysics Environment (멀티피직스 환경하의 이방성 구조물 해석)

  • Kim, Jun-Sik;Lee, Jae-Hun;Park, Jun-Young
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.6
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    • pp.140-145
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    • 2011
  • An anisotropic beam model is proposed by employing an asymptotic expansion method for thermo-mechanical multiphysics environment. An asymptotic method based on virtual work is introduced first, and then the variables of mechanical displacement and temperature rise are asymptotically expanded by taking advantage of geometrical slenderness of elastic bodies. Subsequently substituting these expansions into the virtual work principle allows us to asymptotically expand the virtual work. This will yield a set of recursive virtual works from which two-dimensional microscopic and one-dimensional macroscopic equations are systematically derived at each order. In this way, homogenized stiffnesses and thermomechanical coupling coefficients are derived. To demonstrate the validity and efficiency of the proposed approach, composite beams are taken as a test-bed example. The results obtained herein are compared to those of three-dimensional finite element analysis.

Static Modeling of a Miniaturized Continuum Robot for Surgical Interventions and Displacement Analysis under Lateral External Loads (중재 시술 적용을 위한 소형 연속체 로봇의 정역학 모델링 및 외부 측면 하중에 의한 변위 분석)

  • Kim, Kiyoung;Woo, Hyunsoo;Cho, Jangho;Shin, Minki;Suh, Jungwook
    • The Journal of Korea Robotics Society
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    • v.15 no.4
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    • pp.301-308
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    • 2020
  • In this paper, we deal with the static modeling of a continuum robot that can perform surgical interventions. The proposed continuum robot is made of stainless steel wires and a multi lumen flexible tube using a thermoplastic elastomer. This continuum robot could be most severely deformed in physical contact with narrow external environments, when a lateral external force acts at the distal tip of the continuum robot. In order to predict the shape and displacement under the lateral external force loading, the forward kinematics, the statics modeling, the force-moment equilibrium equation, and the virtual work-energy method of the continuum robot are described. The deflection displacements were calculated using the virtual work-energy method, and the results were compared with the displacement obtained by the conventional cantilever beam theories. In conclusion, the proposed static modeling and the virtual work-energy method can be used in arrhythmia procedure simulations.

Effective moment of inertia for rectangular elastoplastic beams

  • Faller, Ronald K.;Rosson, Barry T.
    • Structural Engineering and Mechanics
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    • v.7 no.1
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    • pp.95-110
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    • 1999
  • An effective moment of inertia is developed for a rectangular, prismatic elastoplastic beam with elastic, linear-hardening material behavior. The particular solution for a beam with elastic, perfectly plastic material behavior is also presented with applications for beam bending in closed-form. Equations are presented for the direct application of the virtual work method for elastoplastic beams with concentrated and distributed loads. Comparisons are made between the virtual work method deflections and the deflections obtained by using an average effective moment of inertia over two lengths of the beam in the elastoplastic region.

Influence of clamped-clamped boundary conditions on the mechanical stress, strain and deformation analyses of cylindrical sport equipment

  • Yuhao Yang;Mohammad Arefi
    • Geomechanics and Engineering
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    • v.35 no.5
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    • pp.465-473
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    • 2023
  • The higher order shear deformable model and an exact analytical method is used for analytical bending analysis of a cylindrical shell subjected to mechanical loads, in this work. The shell is modelled using sinusoidal bivariate shear strain theory, and the static governing equations are derived using changes in virtual work. The eigenvalue-eigenvector method is used to exactly solve the governing equations for a constrained cylindrical shell The proposed kinematic relation decomposes the radial displacement into bending, shearing and stretching functions. The main advantage of the method presented in this work is the study of the effect of clamping constraints on the local stresses at the ends. Stress, strain, and deformation analysis of shells through thickness and length.

Virtual Prototyping of Area-Based Fast Image Stitching Algorithm

  • Mudragada, Lakshmi Kalyani;Lee, Kye-Shin;Kim, Byung-Gyu
    • Journal of Multimedia Information System
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    • v.6 no.1
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    • pp.7-14
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    • 2019
  • This work presents a virtual prototyping design approach for an area-based image stitching hardware. The virtual hardware obtained from virtual prototyping is equivalent to the conceptual algorithm, yet the conceptual blocks are linked to the actual circuit components including the memory, logic gates, and arithmetic units. Through the proposed method, the overall structure, size, and computation speed of the actual hardware can be estimated in the early design stage. As a result, the optimized virtual hardware facilitates the hardware implementation by eliminating trail design and redundant simulation steps to optimize the hardware performance. In order to verify the feasibility of the proposed method, the virtual hardware of an image stitching platform has been realized, where it required 10,522,368 clock cycles to stitch two $1280{\times}1024$ sized images. Furthermore, with a clock frequency of 250MHz, the estimated computation time of the proposed virtual hardware is 0.877sec, which is 10x faster than the software-based image stitch platform using MATLAB.

A Study on Building an Immersive Virtual Aquarium Using Fluid Animation and Smart Fish Method (유체 애니메이션과 Smart Fish을 이용한 실감형 가상수족관 구축에 관한 연구)

  • Lee, Hyun-Cheol
    • Journal of Korea Multimedia Society
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    • v.12 no.1
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    • pp.130-138
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    • 2009
  • As time spent in front of the computer screens increases, an increasing number of people are using natural landscapes or virtual aquariums as their desktop and screen saver that can provide them with mental comfort. A virtual aquarium is constructed by an animation work that creates a variety of fish that freely move in a random virtual underwater environment to analyze their movement. This paper suggests a method that constructs an immersive virtual aquarium, using fluid animation method that expresses changes of shape of fluid in real time and the Smart Fish technology which is capable of an interaction according to the diverse characteristics of virtual fish. The suggested method can be used in a virtual aquarium, aquarium screen saver, virtual fish-raising game, etc., which express diverse undersea environment.

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Design of steel moment frames considering progressive collapse

  • Kim, Jinkoo;Park, Junhee
    • Steel and Composite Structures
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    • v.8 no.1
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    • pp.85-98
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    • 2008
  • In this study the progressive collapse potential of three- and nine-story special steel moment frames designed in accordance with current design code was evaluated by nonlinear static and dynamic analyses. It was observed that the model structures had high potential for progressive collapse when a first story column was suddenly removed. Then the size of beams required to satisfy the failure criteria for progressive collapse was obtained by the virtual work method; i.e., using the equilibrium of the external work done by gravity load due to loss of a column and the internal work done by plastic rotation of beams. According to the nonlinear dynamic analysis results, the model structures designed only for normal load turned out to have strong potential for progressive collapse whereas the structures designed by plastic design concept for progressive collapse satisfied the failure criterion recommended by the GSA guideline.

Dynamic analysis of multi-functional maintenance platform based on Newton-Euler method and improved virtual work principle

  • Li, Dongyi;Lu, Kun;Cheng, Yong;Zhao, Wenlong;Yang, Songzhu;Zhang, Yu;Li, Junwei;Shi, Shanshuang
    • Nuclear Engineering and Technology
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    • v.52 no.11
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    • pp.2630-2637
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    • 2020
  • The structure design of divertor Multi-Functional Maintenance Platform (MFMP) actuated by hydraulic system for China Fusion Engineering Test Reactor (CFETR) was introduced in this paper. The model of MFMP was established according to maintenance requirements. In this paper, Newton-Euler method and the improved virtual work principle were used, the equivalent driving force of each actuator was obtained through the equivalent Jacobian inverse matrix derived from velocity relationship among the components. The accuracy of the model was verified by ADAMS simulation. The stability control of the heavy-duty components driven by hydraulic cylinders based on Newton-Euler method and improved virtual work principle was established.

Variational approximate for high order bending analysis of laminated composite plates

  • Madenci, Emrah;Ozutok, Atilla
    • Structural Engineering and Mechanics
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    • v.73 no.1
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    • pp.97-108
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    • 2020
  • This study presents a 4 node, 11 DOF/node plate element based on higher order shear deformation theory for lamina composite plates. The theory accounts for parabolic distribution of the transverse shear strain through the thickness of the plate. Differential field equations of composite plates are obtained from energy methods using virtual work principle. Differential field equations of composite plates are obtained from energy methods using virtual work principle. These equations were transformed into the operator form and then transformed into functions with geometric and dynamic boundary conditions with the help of the Gâteaux differential method, after determining that they provide the potential condition. Boundary conditions were determined by performing variational operations. By using the mixed finite element method, plate element named HOPLT44 was developed. After coding in FORTRAN computer program, finite element matrices were transformed into system matrices and various analyzes were performed. The current results are verified with those results obtained in the previous work and the new results are presented in tables and graphs.