• Title, Summary, Keyword: Element

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A Study on the Modification of a Finite Element for Improving Shape Optimization (형상최적화 향상을 위한 유한요소의 개선에 관한 연구)

  • Sung, Jin-Il;Yoo, Jeong-Hoon
    • Proceedings of the KSME Conference
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    • pp.367-371
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    • 2001
  • In the shape optimization based on the finite element method, the accuracy of finite element analysis of a given structure is important to determine the final shape. In case of a bending dominant problem, finite element solutions by the full integration scheme are not reliable because of the locking phenomenon. Furthermore, in the process of shape optimization, the mesh distortion is large due to the change of the structure outline: therefore, we cannot guarantee the accurate result unless the finite element itself is accurate. We approach to more accurate shape optimization to diminish these inaccuracies by improving the existing finite element. The shape optimization using the modified finite element is applied to a two-dimensional simple beam. Results show that the modified finite element have improved the optimization results.

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The Use of Hermite Cubic Element for Inviscid Convective Equations (비점성 대류 방정식의 계산을 위한 Hermite 3차 요소의 사용에 대한)

  • 김진환
    • Journal of Ocean Engineering and Technology
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    • v.7 no.1
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    • pp.99-106
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    • 1993
  • The use of Hermite cubic element, as a possible finite element computation of transport equations containing shocks, has been invesigated. In the present paper the hermite cubic elements are applied to both linear and nonlinear scalar one and two dimensional equations. In the one dimensional problems, numerical results by the hermite cubic element show better than those by the linear element, and the steady state solution by the hermite cubic element yields result with good resolution. This fact proves the superiority of the hermite cubic element in space differencing. In two dimensional case, the results by the hermite cubic element shows a boundary instability, and the use of higher order time differencing method may be necessary for fixing the problem.

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An Analysis of the Reinforced Concrete Circular Ring Sector Plates with Arbitrary Boundary Conditions (I) - Part I Effects of open-angle - (임의의 경계조건을 갖는 철근 콘크리트 선형판의 해석 -제1보 개각의 영향)

  • 조진구
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.33 no.2
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    • pp.94-103
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    • 1991
  • This study was carried out to investigate the engineering characteristics of the R.C circular ring sector plate with various boundary conditions and then to propose a rational and paraical method for application of finite element method to R.C structures. The stiffness matrix of the circular ring sector plate was obtained by using the multi-base coordinate system in which the base-coordinate systems were constructed for each nodal point of the quadrilateral element in order to reflect the complicated boundary conditions conveniently and correctly. The R.C element stiffness matrix was constructed by adding the stiffness coefficients of the steel-bar element into the plate bending element stiffness matrix. Herein, the steel-bar element was treated as the common beam element. Using the above method, the effects of steel-bar can be considered without increasing of the numbers of element and nodal points.

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Contact Heat Transfer Coefficient for Finite Element Analysis in Warm Forging Processes (온간단조 공정의 계면열전달계수)

  • Kang J.H.;Ko B.H.;Jae J.S.;Kang S.S.
    • Transactions of Materials Processing
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    • v.15 no.3
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    • pp.183-188
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    • 2006
  • Heat transfer coefficients have great influence on finite element analysis results in elevated temperature forging processes. Experimentally calculated contact heat transfer coefficient is not suitable for one-time finite element analysis because analyzed temperature will be appeared to be too low. To get contact heat transfer coefficient for one-time finite element analysis, tool temperature in operation was measured with thermocouple and repeated finite element analysis was performed with experimentally calculated contact and cooling heat transfer coefficient. Surface temperature of active tool was obtained comparing measurement and analysis results. Contact heat transfer coefficient for one-time finite element analysis was achieved analyzing surface temperature between repeated finite element analysis and one-time finite element analysis results.

Development of a Rigid- Ended beam Element and a Simplified 3-Dimensional Analysis Method for Ship Structures

  • Seo, Seung-Il;Lim, Sung-Joon
    • Journal of Ship and Ocean Technology
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    • v.3 no.3
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    • pp.13-24
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    • 1999
  • In this paper, a 2-dimensional novel beam element is developed and a method to replace the 3-dimensional analysis with 2-dimensional analysis is proposed. The developed novel beam element named rigid-ended beam element can consider the effect of three kinds of span points within one element, which was impossible in modeling with the ordinary beam element. Calculated results for the portal frame using the rigid-ended beam element agree with the results using membrane element. And also, the proposed simplified 3- dimensional analysis method which includes two step analysis using influence coefficients shows good accuracy. Structural analysis using the rigid-ended beam element and the simplified 3-dimensional method is revealed to have good computing efficiency due to unnecessity of the elements corresponding to the brackets and simplification of 3-dimensional analysis.

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Development of Helical Rod Finite Element for the Dynamic Analysis of Cylindrical Springs (원통형 스프링의 동특성 해석을 위한 헬리컬 로드 유한요소 개발)

  • 김도중;이덕영
    • Journal of KSNVE
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    • v.9 no.3
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    • pp.544-553
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    • 1999
  • A 3-dimensional helical rod finite element is devloped for the dynamic analysis of cylindrical springs. Element matrices are formulated using the Galerkin's method, and an exact static deflection curve is used as a shape function. Because the resultant mass and stiffness matrices of the model are symmetric, effective direct solution method can easily be applied for analysing dynamic behavior of springs. The model is used to analyze the dynamic characteristics of a typical automotive valve spring. The effectiveness of the developed helical rod element is verified by comparing the results of the proposed method with those of a classical theory and experiments. The helical element developed in this study is superior to a straight beam element and a 2-dimensional curved beam element for this problem.

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Nonlinear analysis of PSC bridge with strengthened of externally tendon Considering Construction Sequences (외부강선으로 보강된 PSC 교량의 시공단계별 비선형 해석)

  • Park, Jae-Guen;Lee, Byeong-Ju;Kim, Moon-Young;Shin, Hyun-Mock
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.283-288
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    • 2007
  • This paper presents an analytical prediction of Nonlinear characteristics of prestressed concrete bridges by strengthened of externally tendon considering the work sequence, using beam-column element based on flexibility method and tendon element. The beam-column element was developed with reinforced concrete material nonlinearities which are based on the smeared crack concept. The fiber hysteresis rule of beam-column element is derived from the uniaxial constitutive relations of concrete and reinforcing steel fibers. The tendon element represent the bonded tendon and unbonded tendon behaviors. Beam-column element and tendon element was be subroutine A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of RC and PSC structures was used. The proposed numerical method for prestressed concrete structures by strengthened of externally tendon is verified by comparison with reliable experimental results.

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Static Analysis of Three Dimensional Solid Structure by Finite Element-Transfer Stiffness Coefficent Method Introducing Hexahedral Element (육면체 요소를 도입한 유한요소-전달강성계수법에 의한 3차원 고체 구조물의 정적 해석)

  • Choi, Myung-Soo;Moon, Deok-Hong
    • Journal of the Korea Society For Power System Engineering
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    • v.16 no.1
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    • pp.78-83
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    • 2012
  • The authors suggest the algorithm for the static analysis of a three dimensional solid structure by using the finite element-transfer stiffness coefficient method (FE-TSCM) and the hexahedral element of the finite element method (FEM). MATLAB codes were made by both FE-TSCM and FEM for the static analysis of three dimensional solid structure. They were applied to the static analyses of a very thick plate structure and a three dimensional solid structure. In this paper, as we compare the results of FE-TSCM with those of FEM, we confirm that FE-TSCM introducing the hexahedral element for the static analysis of a three dimensional solid structure is very effective from the viewpoint of the computational accuracy, speed, and storage.

Numerical study on concrete penetration/perforation under high velocity impact by ogive-nose steel projectile

  • Islam, Md. Jahidul;Liu, Zishun;Swaddiwudhipong, Somsak
    • Computers and Concrete
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    • v.8 no.1
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    • pp.111-123
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    • 2011
  • Severe element distortion problem is observed in finite element mesh while performing numerical simulations of high velocity steel projectiles penetration/perforation of concrete targets using finite element method (FEM). This problem of element distortion in Lagrangian formulation of FEM can be resolved by using element erosion methodology. Element erosion approach is applied in the finite element program by defining failure parameters as a condition for element elimination. In this study strain parameters for both compression and tension at failure are used as failure criteria. Since no direct method exists to determine these values, a calibration approach is used to establish suitable failure strain values while performing numerical simulations of ogive-nose steel projectile penetration/perforation into concrete target. A range of erosion parameters is suggested and adopted in concrete penetration/perforation tests to validate the suggested values. Good agreement between the numerical and field data is observed.

A high precision shear deformable element for free vibration of thick/thin composite trapezoidal plates

  • Haldar, S.;Manna, M.C.
    • Steel and Composite Structures
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    • v.3 no.3
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    • pp.213-229
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    • 2003
  • A high precision shear deformable triangular element has been proposed for free vibration analysis of composite trapezoidal plates. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has fifty-five degrees of freedom, which has been reduced to forty-eight by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different side ratios (b/a), boundary conditions, thickness ratios (h/a=0.01, 0.1 and 0.2), number of layers and fibre angle orientations have been analyzed by the proposed shear locking free element. Trapezoidal laminate with concentrated mass at the centre has also been analyzed. An efficient mass lumping scheme has been recommended, where the effect of rotary inertia has been included. For validation of the present element and formulation few results of isotropic trapezoidal plate and square composite laminate have been compared with those obtained from open literatures. The numerical results for composite trapezoidal laminate have been given as new results.