• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.11-16
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• 2017

The accurate prediction of leakage flow through the brush element of brush seal at the steam turbine is important to find optimum design parameters for increasing an efficiency. In this study, CFD analysis method using commercial software FLUENT is proposed to predict leakage through the brush element. Since the brush element has a complex three-dimensional shape with many bristle assemblies, it is difficult to analyze the flow field. Therefore, if the brush element is assumed to be porous medium region, the analysis time can be shortened. Two determination methods of resistance coefficients of the Darcian porous medium equation are suggested. By comparing the 2D and 3D CFD analysis results for the leakage of the brush element using the two resistance coefficient determination methods, the effectiveness of the analysis for the porous medium assumption is proved.

• Computers and Concrete
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• v.11 no.5
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• pp.399-410
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• 2013

A nonlinear finite element analysis of R/C hybrid deep T-beam with web opening subjected to pure torsion is presented. Hexahedral 8-nodes and space truss element were used for modeling concrete and reinforcement. The reinforcement was assumed perfectly bonded to the corresponding nodes of the concrete element. The constitutive relations for concrete and reinforcement are based on the modified field theory and elastic perfectly plastic. The smear crack approach was adopted for modeling the crack. The torque-twist angle relationship curve based on the finite element analysis was compared to the experimental results. The comparison shows that the curve of torque-twist angle predicted by the nonlinear finite element analysis is linear before cracking and close to the experimental result. After cracking, the curve becomes nonlinear and stiffer compared to the experimental result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1703-1711
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• 2003

An elastic-plastic finite element analysis is performed to investigate detailed closure behaviour of fatigue cracks in residual stress fields and the numerical results are compared with experimental results. The finite element analysis performed under plane stress using contact elements can predict fatigue crack closure behaviour. The mesh of constant element size along crack surface can not predict the opening level of fatigue crack. Specially, the mesh of element sizes depending upon the reversed plastic zone size included the effect of crack opening point can precisely predict the opening level. By using the concept of the mesh of element sizes depending upon the reversed plastic zone size included the effect of crack opening point, the opening level of fatigue crack can be determined very well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.85-89
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• 2005

For the analysis of a vibrating two dimensional structure such as the simply supported rectangular plate, Spectral Finite Element Method (SFEM) has been studied. Under the condition that two parallel edges are simply supported at least and the other two edges can be arbitrary, Spectral Finite Element has been developed. Using this element SFEM is applied to the vibrating rectangular plate which all edges are simply supported, and obtain the frequency response function in frequency domain and the dynamic response in time domain. To evaluate these results normal mode method and finite element method (FEM) are also accomplished and compared. It is seen that SFEM is more powerful analysis tool than FEM in high frequency range.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.23-30
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• 1997

Modelling and crashworthiness analysis of simplified vehicle structures with beam element and nonlinear spring element to which axial and bending collapse mecha- nisms are applied are carried out. And on the basis of these analyses, two types of full car modelling and crahworthiness analyses with nonlinear spring and beam element are accomplished. The one is the full car model of which 30% of the structures are modelled with nonlinear spring and beam element, and the other 75% of whole structures. And the results are compared with those of full car analysis with shell element.

• Transactions of Materials Processing
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• v.26 no.5
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• pp.293-299
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• 2017

In this paper, finite element stamping analysis was carried out for the front lower arm to examine the applicability of solid element with damage theory to predict shear fracture phenomena induced by sheared edge as well as deformation mechanisms. Mechanical properties related to deformation and damage theory were determined from tensile test. Shear fracture was predicted by normalized Cockcroft-Latham model with initial imposition of the damage value along the sheared edge. Simulation results illustrated that the analysis with solid element and damage theory predicted edge profile, strain distribution, and forming load more accurately than the analysis with shell element. Simulation with solid element can also predict the shear fracture more exactly comparing to analysis with shell element and forming limit curve.

• Advances in Computational Design
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• v.1 no.2
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• pp.207-220
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• 2016

The aim of this study is to investigate the effect of stiffened element and edge stiffener in the behaviour and flexural strength of built-up cold-formed steel beams. An experimental and analytical analysis of CFS channel sections in four different geometries is conducted, including simple channel sections, a stiffened channel section with or without edge stiffeners. Nonlinear finite element models are developed using finite element analysis software package ANSYS. The FEA results are verified with the experimental results. Further, the finite element model is used for parametric studies by varying the depth, thickness, and the effect of stiffened element, edge stiffener and their interaction with compression flanges on stiffened built-up cold-formed steel beams with upright edge stiffeners. In addition, the flexural strength predicted by the finite element analysis is compared with the design flexural strength calculated by using the North American Iron and Steel Institute Specifications for cold-formed steel structures (AISI: S100-2007) and suitable suggestion is made.

• Computers and Concrete
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• v.31 no.3
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• pp.223-239
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• 2023

Geometric nonlinear performance simulation and analysis of complex modern buildings and industrial products require high-performance shell elements. Balancing multiple aspects of performance in the one geometric nonlinear analysis element remains challenging. We present a new shell element, flat shell DKMGQ-CR (Co-rotational Discrete Kirchhoff-Mindlin Generalized Conforming Quadrilateral), for linear and geometric nonlinear analysis of both thick and thin shells. The DKMGQ-CR shell element was developed by combining the advantages of high-performance membrane and plate elements in a unified coordinate system and introducing the co-rotational formulation to adapt to large deformation analysis. The effectiveness of linear and geometric nonlinear analysis by DKMGQ-CR is verified through the tests of several classical numerical benchmarks. The computational results show that the proposed new element adapts to mesh distortion and effectively alleviates shear and membrane locking problems in linear and geometric nonlinear analysis. Furthermore, the DKMGQ-CR demonstrates high performance in analyzing thick and thin shells. The proposed element DKMGQ-CR is expected to provide an accurate, efficient, and convenient tool for the geometric nonlinear analysis of shells.

• Transactions of Materials Processing
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• v.9 no.3
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• pp.304-312
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• 2000

An inverse finite element approach is employed to efficiently design the optimum blank shape and intermediate shapes from the desired final shape in multi-stage elliptic cup drawing processes. The multi-stage deep-drawing process is difficult to design with the conventional finite element analysis since the process is very complicate with the conventional finite element analysis since the process is very complicated with intermediate shapes and the numerical analysis undergoes the convergence problem even with tremendous computing time. The elliptic cup drawing process needs much effort to design sine it requires full three-dimensional analysis. The inverse analysis is able to omit all complicated and tedious analysis procedures for the optimum process design. In this paper, the finite element inverse analysis provides the thickness strain distribution of each intermediate shape through the multi-stage analysis. The multi-stage analysis deals with the convergence among intermediate shapes and the corresponding sliding constraint surfaces that are described by the analytic function of merged-arc type surfaces.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.340-343
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• 2007

This paper introduces a new approach to consider the bending history in finite element inverse analysis of the cylindrical cup drawing. A modified membrane element is adopted to add the bending-unbending energy to the total plastic energy on the bending-unbending region predicted from the geometry of the final shape and tools. The algorithm suggested was applied to a cylindrical cup deep drawing process. The blank shape and the distribution of the thickness strain are compared with those obtained from incremental finite element analysis. The comparison demonstrates the algorithm proposed reduces the difference between the results from inverse analysis and those from incremental analysis when the bending history is considered.