• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2297-2304
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• 2002

Two-dimensional and three-dimensional finite element methods have been used to analyze the deformation behavior of a shadow mask due to thermal and tension load. The shadow mask inside the Braun tube of a TV set has numerous slits through which the electron beams are guided to land on the designed phosphor of red, green or blue. Its thermal deformation therefore causes landing shift of the electron beam and results in decolorization of a screen. For the realistic finite element analysis, the effective thermal conductivity and the effective elastic modulus arc calculated, and then the shadow mask is modeled as shell without slits. Next a transient thermal analysis of the shadow mask is performed, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermal deformation is followed, from which the landing shift of the electron beam is obtained. The present finite element scheme may be efficiently used to reduce thermal deformation of a shadow mask and in developing prototypes of a large screen flat TV.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.248-258
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• 1992

Three-dimensional rigid-plastic finite element formulation based on the membrane theory was described and a computer program for large deformation analysis was developed. In the formulation, normal and planar anisotropy of sheet material and rotation of the principal axes of anisotropy was taken into consideration. Sheet metal was assumed to be rigid-plastic material obeying Hill's quadratic yield criterion and its associated flow rule. Deep drawing process, as a preliminary test, for normal anisotropic material was analyzed in order to examine the validity of developed finite element program. The results were consistent with the existing finite element solutions or experimental data. The present study was mainly concerned with the influence of planar anisotropy on deformation behaviour. Finite element analysis and experiment were carried out for the whole process of deep drawing of planar anisotropic material. The computational and experimental results on the shape of ear, strain distribution and punch load were in good agreement.

• Computational Structural Engineering
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• v.7 no.2
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• pp.111-120
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• 1994

Cracks in rubber bonded to a rigid material such as steel are analyzed with the aid of a mixed finite element technique. Firstly the weak form is derived for finite element analysis of an incompressible material, and the Mooney-Rivlin form is assumed for the constitutive modeling of rubber. The numerical results from finite element analysis is examined to confirm the accuracy and convergence of solution by way of comparison to other numerical results. The interpretation of the J-integral for large elastic deformation as the energy release rate is confirmed, and the J-integral is calculated for varing crack length. The crack growth stability is discussed using the result of finite element analysis.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.1-18
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• 2020

For the large deformation of shear walls under vertical and horizontal loads, there are difficulties in obtaining accurate simulation results using the response analysis method, even with fine mesh elements. Furthermore, concrete material nonlinearity, stiffness degradation, concrete cracking and crushing, and steel bar damage may occur during the large deformation of reinforced concrete (RC) shear walls. Matrix operations that are involved in nonlinear analysis using the traditional finite-element method (FEM) may also result in flaws, and may thus lead to serious errors. To solve these problems, a planar four-node element was developed based on vector mechanics. Owing to particle-based formulation along the path element, the method does not require repeated constructions of a global stiffness matrix for the nonlinear behavior of the structure. The nonlinear concrete constitutive model and bilinear steel material model are integrated with the developed element, to ensure that large deformation and damage behavior can be addressed. For verification, simulation analyses were performed to obtain experimental results on an RC shear wall subjected to a monotonically increasing lateral load with a constant vertical load. To appropriately evaluate the parameters, investigations were conducted on the loading speed, meshing dimension, and the damping factor, because vector mechanics is based on the equation of motion. The static problem was then verified to obtain a stable solution by employing a balanced equation of motion. Using the parameters obtained, the simulated pushover response, including the bearing capacity, deformation ability, curvature development, and energy dissipation, were found to be in accordance with the experimental observation. This study demonstrated the potential of the developed planar element for simulating the entire process of large deformation and damage behavior in RC shear walls.

• Journal of Mechanical Science and Technology
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• v.14 no.6
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• pp.666-674
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• 2000

Large deflection dynamic responses of laminated composite cylindrical shells under impact are analyzed by the geometrically nonlinear finite element method based on a generalized Sander's shell theory with the first order transverse shear deformation and the von-Karman large deflection assumption. A modified indentation law with inelastic indentation is employed for the contact force. The nonlinear finite element equations of motion of shell and an impactor along with the contact laws are solved numerically using Newmark's time marching integration scheme in conjunction with Akay type successive iteration in each step. The ply failure region of the laminated shell is estimated using the Tsai- Wu quadratic interaction criteria. Numerical results, including the contact force histories, deflections and strains are presented and compared with the ones by linear analysis. The effect of the radius of curvature on the composite shell behaviors is investigated and discussed.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.140-148
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• 2003

An analysis fur the warping process has been performed to design the warper beam. Nonlinear material response is included in the physical model of polyester yarn. Large deformation finite element simulation considering contact and frictional analysis are used to obtain the pressure on the barrel of the warper beam. Loading condition on the flange is assumed by using the pressure on the barrel, winding number of yarn, Poisson's ratio of fiber, and fiber volume fraction. By using the above loading conditions NASTRAN finite element simulation is performed to calculate stress distribution and deformation of the warper beam. By comparing the deformed shape of the flange with experimental result, loading condition on the flange has been obtained. The obtained loading conditions on the barrel and flange can be utilized to design the warper beam.

• Journal of Auto-vehicle Safety Association
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• v.6 no.1
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• pp.33-40
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• 2014

In this study the cylinder liner deformation which is one of the most influencing factors in a diesel engine oil consumption was performed by the finite element analysis on the basic designed structure consisting of the cylinder block, head and liners under the conditions of assembly, thermal and gas loads. Compared with a large number of other cylinder blocks showing remarkable harmonic orders of the liner distortion, results are excellent. Namely. the higher harmonic order amplitudes of the radial liner deformation amount to 1 ~ 2㎛ maximally. The main reason lies in the relatively large wall thickness of the liner which amounts to 8.2% of the bore diameter. Besides, a very stiff and symmetrical cylinder block design in combination with a bolt force introduction approximately 1.5mm below the block top deck have a further share on these results. Therefore excellent low oil consumption can be expected.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.64-73
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• 1997

Deformations of structures due to welding appear much complicated and deformated modes are also complex. As parameters governing deformations are various and effect of parameters on deformations is not well known, precise prediction of deformation due to welding has been a difficult problem. Until now, many research papers as to welding deformation have been published, but the research results can explain only one aspect of welding deformation have been published, but the research results can explain only one aspect of welding deformation and are hard to be used in reasonable prediction of welding deformations in complicated structures. In this study, based on the accumulated results concerning to welding deformations, a practical method to predict complicated welding deformations of large structure is proposed. A simplified model to estimate residual plastic strains is suggested and main parameters affecting residual plastic strains are shown to be heat input and joint restaints. Inherent strain theory and experimental data are combined with the finite element method and welding deformations of large structures are calculated by elastic analysis. Comparison of calculated results with experimental data shows the accuracy and validity of the proposed method.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.207-214
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• 2002

A constitutive model was implemented in ABAQUS code, The constitutive equation can model the behavior for overall range of strain level from small to large deformation, which is based on anisotropic hardening rule and total stress concept. The formulation includes (1) finite strain formulation on the basis of Jaumann rate, (2) implicit stress integration and (3) consistent tangent moduli. Therefore, the mathematical background was established in order that large deformation analysis can be performed accurately and efficiently with the anisotropic constitutive model. Companion paper(Jeon et al., 2002) will contain the large deformation analysis results of examples with the constitutive model using ABAQUS.

• Transactions of Materials Processing
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• v.5 no.4
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• pp.297-304
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• 1996

A process model is formulated considering the effect of crystallographic texture developed in forming process. The deformation induced plastic anisotropy can be predicted by capturing the evolution of texture during large deformation in the polycrystalline aggregate. The anisotropic stiffness matrix for the aggregate is derived and implemented in Eulerian finite element code using a Consistent Penalty method. As an application the evolution of texture in rolling drawing and extrusion processes are simulated. The numerical results show good agreements with report-ed experimental textures.