• Title/Summary/Keyword: vertex degree of freedom

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The Shell Elements with vertex Degree of Freedoms (Shell요소의 Normal Rotation)

  • Cho, Soon-Bo
    • Proceeding of KASS Symposium
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    • 2006.05a
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    • pp.256-264
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    • 2006
  • This paper describes the formulation of rectangular flat shell element that is modeled with the six degree of freedoms including a rotational degree of freedom. The rectangular finite element matrix with a rotational degree of freedom is developed using a beam stiffness matrix and compared with other methods. The outputs of the quantity of vertical deflection of cantilever beam show us the improving evidence of the Frame-Shell finite element matrix in a calculation of vertical deflections of cantilever beam.

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The Finite element with Normal Rotational Degree Freedoms (유한요소의 Normal rotation 연구)

  • Cho, Soon-Bo
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.4 s.14
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    • pp.85-89
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    • 2004
  • A frame element embedded normal to a shear wall or slab (shell element) is common in the structural systems. In that case there is a need for a membrane or shell element to have a normal rotation degree of freedom at each node in order to have a good result of stresses. Even if Many other people studied this area, All man, Cook and Sabir are representative investigators in this area. In this research paper, Sabir's methods of vertex rotation stiffness matrix in a membrane element are studied. New stiffness of vertex rotation are proposed by taking advantage of beam stiffness theory. Rectangular elements stiffness with rotational degree of freedom are compared in accuracy ratio each other.

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p-Adaptive Analysis by Three Dimensional Hierarchical Hexahedral Solid Element (3차원 계층적 육면체 고체요소에 의한 p-적응적 해석)

  • Woo, Kwang-Sung;Jo, Jun-Hyung;Shin, Young-Sik
    • Journal of Korean Association for Spatial Structures
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    • v.8 no.4
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    • pp.81-90
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    • 2008
  • This paper presents a finite element formulation for the three-dimensional hierarchical solid element using Integrals of Legendre polynomials. The proposed hexahedral solid element is composed of four different modes including vertex, edge, face, and internal mode, respectively. The eigenvalue and patch test have been carried out to confirm the zero-energy mode and constant strain condition. In addition to these, a posteriori error estimation has been studied for the p-adaptive finite element analysis that is based on a smoothing technique to compute a post-processed solution from the finite element solution. The uniform p-refinement and non-uniform p-refinement are compared in terms of convergence rate as the number of degree of freedom is increased. The simple cantilever beam is tested to show the performance of the proposed solid element.

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Measurement of 3D Object Size Using 6 Axis Sensor (6축 센서를 이용한 3D형상의 면적 산출 방법)

  • Choi, Kyung-Won;Kim, Yung-Jun;Choi, Jong-Woon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.325-327
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    • 2007
  • We report a simple area measurement device for 3 dimensional object using 3 degree of freedom sensor. The surface of 3D object can be divided into a number of triangles, and the surface area of 3D object could be measured by the sum of the divided triangle area. We applied 6DOF sensor to measure the coordinate of triangle vertex, and calculated each triangle area on the surface of 3D object. The many we divide the area to triangles, the correct we will get the result. This method shows 7.78% in error on the measurement of 3 dimensional object area.

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Prediction of Aeroelastic Displacement Under Close BVI Using Unstructured Dynamic Meshes (비정렬 동적격자를 이용한 블레이드-와류 간섭에 따른 공탄성 변위예측)

  • Jo, Kyu-Won;Oh, Woo-Sup;Kwon, Oh-Joon;Lee, In
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.37-45
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    • 2002
  • A two-dimensional unsteady, inviscid flow solver has been developed for the simulation of airfoil-vortex interactions on unstructured dynamically adapted meshes. The Euler solver is based on a second-order accurate implicit time integration using a point Gauss-Seidel relaxation scheme and a dual time-step subiteration. A vertex-centered, finite-volume discretization is used in conjunction with the Roe's flux-difference splitting. An unsteady solution-adaptive dynamic mesh scheme is used by adding and deleting mesh points to take account of both spatial and temporal variations of the flow field. The effect of vortex interaction on the aeroelastic displacement of an airfoil attached to the idealized two degree-of-freedom spring system is investigated.

Low velocity impact response and dynamic stresses of thick high order laminated composite truncated sandwich conical shell based on a new TDOF spring-mass-damper model considering structural damping

  • Azizi, A.;Khalili, S.M.R.;Fard, K. Malekzadeh
    • Steel and Composite Structures
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    • v.26 no.6
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    • pp.771-791
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    • 2018
  • This paper deals with the low velocity impact response and dynamic stresses of composite sandwich truncated conical shells (STCS) with compressible or incompressible core. Impacts are assumed to occur normally over the top face-sheet and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The displacement fields of core and face sheets are considered by higher order and first order shear deformation theory (FSDT), respectively. Considering continuity boundary conditions between the layers, the motion equations are derived based on Hamilton's principal incorporating the curvature, in-plane stress of the core and the structural damping effects based on Kelvin-Voigt model. In order to obtain the contact force, the displacement histories and the dynamic stresses, the differential quadrature method (DQM) is used. The effects of different parameters such as number of the layers of the face sheets, boundary conditions, semi vertex angle of the cone, impact velocity of impactor, trapezoidal shape and in-plane stresses of the core are examined on the low velocity impact response of STCS. Comparison of the present results with those reported by other researchers, confirms the accuracy of the present method. Numerical results show that increasing the impact velocity of the impactor yields to increases in the maximum contact force and deflection, while the contact duration is decreased. In addition, the normal stresses induced in top layer are higher than bottom layer since the top layer is subjected to impact load. Furthermore, with considering structural damping, the contact force and dynamic deflection decrees.

PREDICTION OF SEPARATION TRAJECTORY FOR TSTO LAUNCH VEHICLE USING DATABASE BASED ON STEADY STATE ANALYSIS (정상 해석 기반의 데이터베이스를 이용한 TST 비행체의 분리 궤도 예측)

  • Jo, J.H.;Ahn, S.J.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.19 no.2
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    • pp.86-92
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    • 2014
  • In this paper, prediction of separation trajectory for Two-stage-To-Orbit space launch vehicle has been numerically simulated by using an aerodynamic database based on steady state analysis. Aerodynamic database were obtained for matrix of longitudinal and vertical positions. The steady flow simulations around the launch vehicle have been made by using a 3-D RANS flow solver based on unstructured meshes. For this purpose, a vertex-centered finite-volume method was adopted to discretize inviscid and viscous fluxes. Roe's finite difference splitting was utilized to discretize the inviscid fluxes, and the viscous fluxes were computed based on central differencing. To validate this flow solver, calculations were made for the wind-tunnel experiment model of the LGBB TSTO vehicle configuration on steady state conditions. Aerodynamic database was constructed by using flow simulations based on test matrix from the wind-tunnel experiment. ANN(Artificial Neural Network) was applied to construct interpolation function among aerodynamic variables. Separation trajectory for TSTO launch vehicle was predicted from 6-DOF equation of motion based on the interpolated function. The result of present separation trajectory calculation was compared with the trajectory using experimental database. The predicted results for the separation trajectory shows fair agreement with reference[4] solution.