• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.3
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• pp.270-277
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• 1983

Plastic plane stress solutions are given for a center cracked strip, characterized by the Ramberg-Osgood plastic index, under bi-axial tension. Using a power law hardening stress-strain relation, an incremental plasticity finite element formulation is developed, and simple formulation is given for computing J-integral with nodal displacements. The near tip angular distribution of von Mises effective stress doesn't differ significantly in magnitude according to the change of loading stress and bi-axial load combination factor. But, for smaller plastic index, the location of its maximum value moves vertically at a head of crack. J-integral value, in the plastic zone near crack tip, decreases with load combination factor for large and small plastic index.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1889-1900
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• 1995

In this study, a large deflection analysis of a plane frame composed of a thin-walled tube in investigated. When bent, a thin-walled tube is usually controlled by local buckling and subsequent bending collapse of the section. So load resistance reaches the yield level in a thin-walled rectangular tube. This relationship can be divided into three regimes : elastic, post-buckling and crippling. In this paper, this relationship is theoretically presented to be capable of describing nonlinearities and a stiffness matrix is derived by introducing a compound beam-spring element. A numerical analysis uses a constant incremental energy method and the solution is obtained by modifying stiffness matrix at elastic/inelastic stage. This analytical results, load-deflection paths show a good agreement with the test results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06b
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• pp.28-42
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• 1998

Spinning is one of the incremental forming process by the rotating mandrel and forming roller, and has been applied to manufacturing the wheel disc of automobile to simplify the manufacturing process and to improve the mechanical properties of product. In the proesent study the process variables have been extracted and considered to decide the specification of the spinning machine. The maximum values of working load and power have been evaluated and the blank size has been disigned. The shape and dimensionof forming roller have been designed and the process condition such a s rotational velocity of mandrel and the feedrate of roller have been decided.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.327-334
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• 2001

This paper presents a non-linear analysis procedure for plane frame structures by finite element formulation with assumptions of Timoshenko beam theory. Finite element displacement method based on Lagrangian formulation is used and two-noded and isoparametric line element is adopted to represent finite element model. The layered approach is used for the elasto-plastic analysis of the plane frame structures with rectangular and I cross sections. A load incremental method combined with the tangent stiffness and the initial stiffness methods for each load increment is used for the solution of non-linear equations. Numerical examples are presented to investigate the behavior and the accuracy of the elasto-plastic non-linear application and the results of this study are compared with other solutions using the concept of plastic hinge.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.395-402
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• 1999

This paper discusses the theoretical researches subject to elastic buckling problems of the structures. The purpose is to ensure the characteristic of buckling be true by arc-length method and the finite element method. The difficulties in processes calculating the equilibrium curve after buckling is to get the equilibrium owe near singular point at which the determinant of stiffness matrix is zero. The purpose of the load-displacement curve is to determine the buckling load of the structure, and further to get the information about the characteristic after buckling. Here, this paper expresses the incremental solution at particular point by the linear combination of both homogeneous mode and particular mode, then uses the method which gets the unknown parameter including this function, through trial-and-error method including modified N-R convergence process. Finally, this paper describes the multiple bifurcation of truss dome as the numerical examples according to this algorithm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.2
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• pp.56-61
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• 2000

In the paper, the system loss sensitivity index that implies the incremental system loss with respect to the change of bus power is derived using optimization technique. The index λ reaches $\infty$ at critical loading point and can be applied to actual power systems for following purposes. 1) Evaluation of system voltage stability 2)Optimal investment of reactive power focused on minimizing system loss and maximizing system voltage stability 3)Optimal re-location of reactive power focused on minimizing system loss and maximizing system voltage stability 4)Optimal load shedding in case of severe system contingency focused on minimizing system loss and maximizing system voltage stability. Case studies for each application have proved their effectiveness.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.90-100
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• 2000

The present paper investigates the elasto-plastic buckling of ball-jointed single layer latticed domes considering the connection characteristics. The domes are composed of tubular member elements, ball joints and connectors. To judge yielding of the member, the ends and central part of tubular member elements are assumed as five elasto-plastic springs. Elasto-plastic buckling load can be identified the yielding load of estimated member As a numerical analysis technique, loading incremental method based on the Newton-Raphson method is used. The effects of connection characteristics are investigated by the following points; (1) the length of rigid zone, (2) looseness of screw, (3) diameter of connector Finally, it is emphasized that the connection characteristics as well as the material non-linearity have significant effects upon the buckling toad of domes.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.205-228
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• 2015

The results of a numerical investigation pertaining to the hysteretic behaviour of concrete filled steel tubular (CFT) column to I-beam connections are discussed in detail. Following the verification of the numerical results against the available experimental tests, the nonlinear finite element (FE) analysis was implemented to evaluate the effects of different parameters including the column axial load, beam lateral support, shape and arrangement of stiffeners, stiffness of T-stiffeners, and the number of shear stiffeners. Pursuing this objective, an external CFT column to beam connection, tested previously, was selected as the case-study. The lateral forces on the structure were simulated, albeit approximately, using an incremental cyclic loading reversal applied at the beam tip. The results were compared in terms of hysteretic load-displacement curves, stress distributions in connection, strength, rotation, and energy dissipation capacity. It was shown that external T-stiffeners combined with internal shear stiffeners play an important role in the hysteretic performance of CFT columns to I-beam connections.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.71-79
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• 2023

In this study, a prefabricated buckling brace (PF-BRB) was proposed, and a test specimen was manufactured based on the design formula for the initial shape and structural performance tests were performed. As a result of the experiment, all standard performance requirements presented by KDS 41 17 00 and MOE 2021 were satisfied before and after replacement of the reinforcement module, and no fracture of the joint module occurred. As a result of the incremental load test, the physical properties showed a significant difference in the stiffness ratio after yielding under the compressive load of the envelope according to the experimental results. It is judged necessary to further analyze the physical properties according to the experimental results through finite element analysis in the future.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.55-62
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• 1990

In this paper, another method for system reliability analysis, called the extended incremental load method, is introduced. The method is an extension of the conventional incremental load method and has been developed aiming at evaluating the probability of system failure(or system reliability) of continuous structures such as floating offshore structures under the multiple loading condition, more realistically considering the post-ultimate behaviour of failed components and directly using the strength formulae of principle components in a structure with employing the modified safety margin equation proposed herein in the system analysis. The method has been applied to the Hutton TLP operated in the Hutton field in the North Sea and a certain variant of the design using the TLP Rule Case Committee type improved strength models. System failure probability and corresponding system reliability indices are derived for a more economical and efficient design. The redundancy characteristics are also addressed. The TLP forms are shown to possess high reserve strength and system safety.