• Computational Structural Engineering
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• v.7 no.2
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• pp.139-146
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• 1994

In this study, the finite element analysis using joint elements, bolt elements, and shell elements is presented to investigate the behavior of bolted connections. The contact of plates and the high-strength, pretensioned bolts are simply idealized by joint elements and bolt elements, respectively. The initial stiffness is determined through the presented method and the non-linear analysis is archived by a constant-arc-length method based on Newton-Raphson method. The analysis results of a semi-rigid connection(web & flange angles) and a moment connection (shear & moment plates) demonstrate the exactness and applicability of the presented method. And the results indicates that the consideration of slip and 3-dimensional deformation is needed for an accurate prediction of bolted connections.

• Composites Research
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• v.16 no.4
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• pp.1-9
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• 2003

2 ply laminated composite is regarded to simulate the interply behavior of the belt layer of the tire. It was cone with 3 dimensional FE(Finite Element) analysis to determine interply shear stress and strain. Widthwise, the shear strain was measured by the pin method. These results are compared with those of CLT(classical lamination theory) in center region and those of Kassapoglou's and Kelsey's theory in edge region. In the FE analysis. rubber is assumed as linear elastic material. and rubber/cord laminate as the orthotropic material composed of cord and rubber In the FE result, interlaminar shear stress causing the interlaminar delamination has the largest value in the edge region of the inner rubber layer. Numerical results obtained coincides with CLT well in the center region, and agrees with other theoretical result little in the edge region.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.375-387
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• 2004

A new finite element model will be presented to analyze the nonlinear behavior of RC beams and slabs strengthened by a patch repair. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on hardening rule, crushing condition, plate-end debonding strength model and so on. The Gauss-Lobatto numerical quadrature is applied to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed p-version nonlinear finite element model is demonstrated through the load-deflection curves, the ultimate loads, and the failure modes of RC beams or slabs bonded with steel plates or FRP plates compared with available result of experiment and other numerical methods.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.118-127
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• 2010

Resistivity logging instruments are designed to measure the electrical resistivity of a formation, and this can be directly interpreted to provide a water-saturation profile. However, resistivity logs are sensitive to borehole and shoulder-bed effects, which often result in misinterpretation of the results. These effects are emphasised more in the presence of tool eccentricity. For precise interpretation of short- and long-normal logging measurements in the presence of tool eccentricity, we simulate and analyse eccentricity effects by combining the use of a Fourier series expansion in a new system of coordinates with a 2D goal-oriented high-order self-adaptive hp finite-element refinement strategy, where h denotes the element size and p the polynomial order of approximation within each element. The algorithm automatically performs local mesh refinement to construct an optimal grid for the problem under consideration. In addition, the proper combination of h and p refinements produces highly accurate simulations even in the presence of high electrical resistivity contrasts. Numerical results demonstrate that our algorithm provides highly accurate and reliable simulation results. Eccentricity effects are more noticeable when the borehole is large or resistive, or when the formation is highly conductive.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.257-265
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• 2004

The aim of this study is to investigate the inelastic buckling behavior of the beams under moment gradient using a line-type finite element method. The method is incorporated the non-uniform yielding of the cross-section caused by the presence of residual stress and accepted model of residual stress so called 'simplified' and 'polynomial' pattern is adopted in this study. The inelastic lateral-torsional buckling results obtained in this study is compared with the buckling results obtained from the design method based on the allowable stress method given in Korean Steel Designers Manual (KSDM 1995). This study have found that the design method in KSDM (1995) is conservative without and with intermediate bracing applied at the mid span of the beam, and there is some scope for improving the provisions of KSDM (1995)

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.4
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• pp.1-11
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• 2001

A theory for time-dependent, high temperature ablation of poroelastic carbon composite insulators is applied using finite element methods to determine material properties from experimental data. The theory contains important revisions to that in Lee, Salamon and Sullivan[1] by making a sharp distinction between Biots constants and permeability and setting both to analytical functions of porosity. The finite element program and material modeling has been modified to (1) more closely adhere to porous-material theory, (2) include a newly discovered analytical simplification and (3) refine the material property descriptions. Application to experimental problems and comparisons with data permit determination of Biots constants and permeability and their evolution with respect to matrix decomposition and clearly show how material parameters affect the material response, e.g., amplitude and the location of peaks with respect to temperature. In particular, the response is very sensitive to permeability and dominated by it.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.89-94
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• 2004

A steel plated is typically composed of plate panels. The overall failure of the structure is certainly affected and can be governed by the bulking and plastic collapse of these individual members. In the ultimate limit state design, therefore, a primary task is to accurately calculate the buckling and plastic collapse strength of such structural members. Structural elements making up steel palated structures do not work separately, resulting in high degree of redundancy and complexity in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed, simplifications or idealizations must essentially be made considering the accuracy need and degree of complexity of the analysis to be used. Generally the more complex the analysis the greater is the accuracy that may be obtained. The aim of this study is the investigation of the effect of the tripping behaviour including section characteristic for a plate under uniaxial compression. For this purpose of study, in used elasto-plasticity deformation FEA method are used for this study.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.307-316
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• 2002

In order to evaluate the deformation and stiffness of frame structure for fishery, composed of unit platforms which made of two concentric high density polyethylene buoys fixed by clamps and belts and rubber hinge components, under wave, the structural analysis for the square type of the structure was carried out by using finite element methods. The accurate physical properties of rubber hinge components determined by material tests were an important parameter to evaluate more reliable structural stability for the structure. The idealization to beam element with equivalent stiffness and rubber element with linearity for rubber hinges was necessary for the modeling of rubber component which has hyper-elastic characteristics. In addition, it was shown that the structural response of the structure under wave was larger in the hogging condition than that of in the still water or in the sagging condition.

• Composites Research
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• v.14 no.3
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• pp.69-76
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• 2001

This paper proposes a double cantilever sandwich-beam method fur evaluating the frequency dependence of dynamic characteristics of rubbers. The flexural vibration of a double cantilever sandwich-beam specimen with an inserted rubber layer was studied using a finite element simulation in combination with the sine-sweep test. Quadratic relationships of dynamic elastic modulus and material loss factor of rubbers with frequency were suggested employing the least square error method.

• Water for future
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• v.21 no.1
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• pp.67-76
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• 1988

Analyzed was the circulation phenomena in the open channel with sudden expansion, by applying the Galerkin's finite element method to the depth-averaged 2-dimensional continuity and momentum equations. Wave tests were done in the simplified channel in order to review the validity of this newly developed model and the computed results were within 0.5% of $L_2$-norm error, and application of this model to the simulation of simplified dam-break gave very close results compared with the analytical solution, thus, it can be concluded that this model is valid and efficient. The main flow in the expanded channel was defined as a new initial condition with given velocity and the flow in the expanded portion was at rest in simulating the circulation, and besides the Neumann's condition the slip boundary condition for lateral wall was found to be proper condition than the no-slip condition. It can be concluded, from the numerical tests in the sudden expension, that the circulating phenomena depend mainly on the convective inertia and the effect of turbulence due to bottom shear and lateral shear is insignificant.