• Title/Summary/Keyword: shell finite element

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A research on the technique for the vibration analysis of fuid-filled, strength member embedded and semi-infinite cylindrical shell (유체 충진된 반 무한 내심형 원통셸의 진동 해석 기법 연구)

  • Ham, Il-Bae;Bae, Soo-Ryong;Jeong, Weui-Bong
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.12
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    • pp.127-134
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    • 1997
  • Abstract: A technique to analyze the vibrations of internally fluid-filled, semi-infinite cylindrical shell which has strength members embedded in the shell wall under the axial static tension conditon is presented by using the characteristic wave propagation theory based on the transfer matrix calculated from the finite element matrices of a short module section, with spatial Laplace Tranform technique, and is verified by comparison with the measured results of the test performed on a real module model, and the effects of the embedded strength members on the vibrational response is calculated and discussed.

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Nonlinear Analysis of RC Structures using Assumed Strain RM Shell Element

  • Lee, Sang Jin
    • Architectural research
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    • v.16 no.1
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    • pp.27-35
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    • 2014
  • Nonlinear analysis of reinforced concrete structures is carried out by using Reissner-Mindlin (RM) shell finite element (FE). The brittle inelastic characteristic of concrete material is represented by using the elasto-plastic fracture (EPF) material model with the relevant material models such as cracking criteria, shear transfer model and tension stiffening model. In particular, assumed strains are introduced in the formulation of the present shell FE in order to avoid element deficiencies inherited in the standard RM shell FE. The arc-length control method is used to trace the full load-displacement path of reinforced concrete structures. Finally, four benchmark tests are carried out and numerical results are provided as future reference solutions produced by RM shell element with assumed strains.

Post-buckling and Elasto-plastic Analysis of Shell Structures using the Degenerated Shell Element (변형된 쉘요소를 이용한 판 및 쉘 구조의 후좌굴 및 탄.소성 유한요소해석)

  • 김문영;민병철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1995.04a
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    • pp.17-27
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    • 1995
  • For the post-buckling and elasto-plastic analysis of shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors in the iteration process and evaluating the total Green-Lagrange stain corresponding U total displacements. In the calculation of the stiffness matrix, the element formulation takes into account the effect of finite rotation increments by retaining second order rotation terms in the incremental displacement field. The selective or reduced integration scheme using the heterosis element is applied in order to overcome both shear locking phenomena and the zero energy mode. The load/displacement incremental scheme is adopted for geometric non-linear F .E. analysis. Based on such methodology, the computer program is developed and numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references's results.

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Analysis of Thermal Stress and Fatigue Life in the Steel Shell of a Cupola Furnace (큐폴라 용해로 철피의 열응력 및 피로수명 해석)

  • Yang, Young-Soo;Bae, Kang-Yul
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.2
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    • pp.47-54
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    • 2020
  • Themo-mechanical analysis was carried out using the finite element method for the steel shell of a cupola furnace. When the outer surface of the shell was cooled with water to within the temperature range of 35-80 ℃ during operation of the cupola, the inner surface of the shell was expected to exhibit a temperature of 65-248 ℃ based on heat transfer analysis. The shell was also expected to have an equivalent stress range of 100-280 MPa in the outer surface over the temperature range examined. Upon cooling the shell to obtain an outer surface temperature <80 ℃, the maximum equivalent stress of the shell did not exceed the yield strength. Although the temperature of the outer surface varied between 35 and 80 ℃ periodically due to the cooling control problem, the fatigue stress at the outer surface of the shell was calculated to be within the fatigue strength. During a non-operational period to examine the system between furnace operations, the thermal stress presented in the shell was sufficiently low to reach the desired yield strength and fatigue limit.

Residual Deformation Induced by the Repair of Composite Shell Structures (복합재료 쉘 구조물의 수리 시 발생하는 잔류변형)

  • 최항석;정의승;이수용
    • Composites Research
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    • v.12 no.4
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    • pp.17-24
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    • 1999
  • Finite element analysis and experiment are performed to investigate residual deformation induced by the repair of composite shell structures using a prepreg patch method. The finite element program is developed on the basis of a three-dimensional degenerated shell element and the first order shear deformation theory. The results analyzed for the laminated shell with free boundary conditions are compared with strains measured during the prepreg patch repair. Final residual stresses occur greatly near the patch when the laminated shell with all edges clamped is repaired using the prepreg patch. Stacking sequences of the laminated shell and patch affect significantly the residual stresses which occur even if they are the same.

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A weld-distortion analysis method of the shell structures using ultra structural FE model (초대형 구조모델을 활용한 쉘구조물의 용접변형 해석)

  • Ha, Yunsok;Yi, Myungsu
    • Journal of Welding and Joining
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    • v.33 no.3
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    • pp.62-67
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    • 2015
  • A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

A Comparative Analysis of Anisotropic Thick Cylindrical Shells and Anisotropic Thin Cylindrical Shells by Finite Element Method (유한요소법에 의한 비등방성 두꺼운 원통형 쉘 및 얇은 원통형 쉘의 비교 해석)

  • Kim, Gi-Dong;Park, Weon-Tae
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.1 no.3
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    • pp.17-23
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    • 2010
  • This paper is presented for the analysis results of the bending problems of the anisotropic cylindrical shells. In the numerical analysis of various mechanical problems involving complex partial differential equations, Finite element method is used to analyze the governing equations of anisotropic cylindrical shells. Both thin shell theory and thick shell theory are used as the basic governing equations of bending problems in the anisotropic cylindrical shells. The analysis results are compared between the anisotropic thick cylindrical shells and the anisotropic thin cylindrical shells. The results of this study will be contribute to analyze the bending behavior of anisotropic cylindrical shells.

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Deflection Analysis of Laminated Composite Cylindrical Shell Structures Based on Micro-Mechanics (마이크로 역학기반 GFRP 원통형 적층 쉘 구조의 변위 해석)

  • Kim, Gyu-Dong;Lee, Sang-Youl
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.4 no.4
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    • pp.15-21
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    • 2013
  • This study carried out finite element deflection analysis of cylindrical shell structures made of composite materials, which is based on the micro-mechanical approach for different fiber-volume fractions. The finite element (FE) models for composite structures using multi-scale approaches described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the material combination. New results reported in this paper are focused on the significant effects of the fiber-volume fraction for various parameters, such as fiber angles, layup sequences, and length-thickness ratios. It may be concluded from this study that the combination effect of fiber and matrix, largely governing the dynamic characteristics of composite shell structures, should not be neglected and thus the optimal combination could be used to design such civil structures for better dynamic performance.

A Study on Free Vibration of Steel and Composite Cylindrical Shells with an Oblique Angle (경사단을 갖는 Steel 및 복합재료 원통쉘의 자유진동 특성에 관한 연구)

  • Lee, Jang-Won;Choi, Young-Jin;Lee, Young-Shin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.928-933
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    • 2004
  • The vibration characteristic is a primary design factor. The cylindrical shells are used as a primary components of complex structure. also, The cylindrical shells have oblique angle. In this study, The vibrational characteristics of steel and plain wave GFRP cylindrical shell with an oblique end are given by experimental and finite element method. To be find characteristic of the oblique end, the mass of the cylindrical shell is maintained. Natural frequency and mode shapes of isotropic and plain weave composite shells are obtained by modal test. The results are compared with those of the finite element method. The simply supported boundary conditions with bolts along the circumferential direction of the GFRP shell are well achieved. Also, The clamped boundary conditions is applied to the steel specimen. Those are shown to agree well with the analytical results and finite element analysis results.

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Reliability analysis of laminated composite shells by response surface method based on HSDT

  • Thakur, Sandipan N.;Chakraborty, Subrata;Ray, Chaitali
    • Structural Engineering and Mechanics
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    • v.72 no.2
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    • pp.203-216
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    • 2019
  • Reliability analysis of composite structures considering random variation of involved parameters is quite important as composite materials revealed large statistical variations in their mechanical properties. The reliability analysis of such structures by the first order reliability method (FORM) and Monte Carlo Simulation (MCS) based approach involves repetitive evaluations of performance function. The response surface method (RSM) based metamodeling technique has emerged as an effective solution to such problems. In the application of metamodeling for uncertainty quantification and reliability analysis of composite structures; the finite element model is usually formulated by either classical laminate theory or first order shear deformation theory. But such theories show significant error in calculating the structural responses of composite structures. The present study attempted to apply the RSM based MCS for reliability analysis of composite shell structures where the surrogate model is constructed using higher order shear deformation theory (HSDT) of composite structures considering the uncertainties in the material properties, load, ply thickness and radius of curvature of the shell structure. The sensitivity of responses of the shell is also obtained by RSM and finite element method based direct approach to elucidate the advantages of RSM for response sensitivity analysis. The reliability results obtained by the proposed RSM based MCS and FORM are compared with the accurate reliability analysis results obtained by the direct MCS by considering two numerical examples.