• Journal of Power System Engineering
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• v.17 no.2
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• pp.46-55
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• 2013

In this paper, the computational algorithm for free vibration analysis of an axisymmetric cylindrical shell is formulated by the Sylvester-transfer stiffness coefficient method (S-TSCM) which combines the Sylvester's inertia theorem and the transfer stiffness coefficient method. After the computational programs for obtaining the natural frequencies and natural modes of the axisymmetric cylindrical shell are made by the S-TSCM and the finite element method (FEM), the computational results which are natural frequencies, natural modes, and computational times by both methods are compared. From the computational results, we can confirm that S-TSCM has the reliability in the free vibration analysis of the axisymmetric cylindrical shell and is superior to FEM in the viewpoint of computational times.

• Structural Engineering and Mechanics
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• v.52 no.2
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• pp.221-238
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• 2014

A four-noded curved shell finite element for the geometrically non-linear analysis of beams curved in plan is introduced. The structure is conceived as a sequence of macro-elements (ME) having the form of transversal segments of identical topology where each slice is formed using a number of the curved shell elements which have 7 degrees of freedom (DOF) per node. A curved box-girder beam example is modelled using various meshes and linear analysis results are compared to the solutions of a well-known computer program SAP2000. Linear and non-linear analyses of the beam under increasing uniformly distributed loads are also carried out. In addition to box-girder beams, the proposed element can also be used in modelling open-section beams with curved or straight axes and circular plates under radial compression. Buckling loads of a circular plate example are obtained for coarse and successively refined meshes and results are compared with each other. The advantage of this element is that curved systems can be realistically modelled and satisfactory results can be obtained even by using coarse meshes.

• Structural Engineering and Mechanics
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• v.68 no.3
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• pp.299-312
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• 2018

In this paper, an extended finite element method is proposed to analyze both geometric and material non-linear behavior of general Functionally Graded Material (FGM) plate-shell type structures. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the elastoplastic behavior of the ceramic particle-reinforced metal-matrix FGM plates-shells. The standard quadrilateral 4-nodes shell element with three rotational and three translational degrees of freedom per node, S4, is extended in the present study, to deal with elasto-plastic analysis of geometrically non-linear FGM plate-shell structures. The elastoplastic material properties are assumed to vary smoothly through the thickness of the plate-shell type structures. The nonlinear approach is based on Mori-Tanaka model to underline micromechanics and locally determine the effective FGM properties and self-consistent method of Suquet for the homogenization of the stress-field. The elasto-plastic behavior of the ceramic/metal FGM is assumed to follow Ludwik hardening law. An incremental formulation of the elasto-plastic constitutive relation is developed to predict the tangent operator. In order to to highlight the effectiveness and the accuracy of the present finite element procedure, numerical examples of geometrically non-linear elastoplastic functionally graded plates and shells are presented. The effects of the geometrical parameters and the volume fraction index on nonlinear responses are performed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.3
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• pp.110-116
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• 1999

This paper describes the effect of eddy currents in the rotor steel shell of exterior-rotor permanent magnet BLDC motor of which rotor is revolving at a high speed. A two-dimensional time-stepping finite element method is used for analyzing electromagnetic field and computing performances of the motor. As a result the effect of the eddy currents in the rotor steel shell is shown by comparing the analysis results from both the proposed method and the conventional one.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.195-200
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• 2001

Numerical procedures for the geometrically nonlinear finite element analysis of prestressed concrete shell structures under tendon-induced nonconservative loads have been presented. The equivalent load approach is employed to realize the effect of prestressing tendon. In this study, the tendon-induced nonconservative loads are rigorously formulated into the load correction stiffness matrix(LCSM) taking the characteristics of Present shell element into account. Also, improved nonlinear formulations of a shell element are used by including second order rotations in the displacement field. Numerical example shows that beneficial effect on the convergence behavior can be obtained by the realistic evaluation of tangent stiffness matrix according to the present approaches.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2051-2060
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• 1993

A finite element program using degenerated shell element was developed to solve the geometric, material and combined nonlinear behaviors of composite laminated shell. The total Lagrangian method was implemented for geometric nonlinear analysis. The material nonlinear behavior was analyzed by considering the matrix degradation due to the progressive failure in the matrix and matrix-fiber interface after initial failure. The result of the geometric nonlinear analysis showed good agreement with the other exact and numerical solutions. The results of the combined analyses considered both geometric and material nonlinear analyses were compared with the experiments in which internal pressure was applied to the filament wound antisymmetric tubes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.810-815
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• 2002

Vibration analysis of rotating blade is the main purpose of this study. In the present work, general formulation is proposed to analyze the rotating shell-type structures including the effect of centrifugal force, Coriolis acceleration and initial twist. Furthermore, simplified equations are derived for the case of an open circular cylindrical shell. Based on the concept of degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is adopted for solving the governing equations. In addition, it is investigated the effect of thermal load on the vibration characteristics of pretwisted blade. Numerical results are summarized for the various parameters such as rotating speed, angle of pretwist and stacking sequence of a composite blade. Also, present results are compared with the previous works and experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.380.1-380
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• 2002

Vibration analysis of rotating blade is the main purpose of present study. In this work, general formulation is proposed to analyze rotating shell type structures including the centrifugal force, Coriolis acceleration and initial twist. Futhermore, simplified equations are derived for the case of an open circular cylindrical shell. Based on the concept of degenerated shell element with the Reissner-Mindlin's assumptions, the finite element method is adopted for solving the governing equations. (onitted)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.794-801
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• 2006

The linkage framework of geometric modeling and analysis based on the NURBS technology is developed in this study. The NURBS surfaces are generated by interpolating the given set of data points or by extracting the necessary information to construct the NURBS surface from the IGES format file which is generated by the commercial CAD systems in the present study. Numerical examples shows the rate of displacement convergence according to the paramterization methods of the NURBS surface. NURBS can generate quadric surfaces in an exact manner. It is the one of the advantages of the NURBS. A trimmed NURBS surface that is often encountered in the modeling process of the CAD systems is also presented in the present study. The performance of the developed geometrically exact shell element integrated with the exact geometric representations by the NURBS equation is compared to those of the previous reported FE shell elements in the selected benchmark problems.

• Architectural research
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• v.20 no.1
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• pp.9-16
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• 2018

Nonlinear analysis of reinforced concrete (RC) structures is performed by using isogeometric Reissner-Mindlin (RM) shell element. The elasto-plastic constitutive model is employed to express the nonlinear behavior of concrete material and the equivalent smeared steel layer is introduced to represent steel reinforcement. The arc-length control method is used to produce the entire load-displacement path of RC structures. Finally, three benchmark tests are carried out to verify the performance of the present shell element. From isogeometric analysis, the present results show a good agreement with experimental results and it is provided as future benchmark test solutions.