• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.421-424
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• 2009

Superplastic deformation behavior and texture evolution after equal channel angular pressing (ECAP) of Zn-0.3Al alloy were investigated in this study. ECAP was conducted at temperatures from $40^{\circ}C$ to $160^{\circ}C$ on the plate type specimens of 5 mm thickness and 20 mm width. The specimens obtained by ECAP showed typical texture with basal poles tilted away from the ND toward ED. A series of compression and tensile tests was carried out at temperatures from RT to $200^{\circ}C$ under the strain rate from 0.03 to 10/s. After ECAP of the Zn-Al alloy, elongation was dramatically increased up to 1000% at above $60^{\circ}C$. The effects of ECAP on the texture and anisotropy in the superplastic deformation bebavior were found to be negligible.

• Elastomers and Composites
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• v.55 no.2
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• pp.88-94
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• 2020

Automobile industry, along with the automobile steering system, is rapidly changing and developing. The constant velocity joint transmits power to the wheels of vehicles without changing their angular velocity based on the movement of the steering wheel. Moreover, it controls their movement to act as a buffer. In order to prevent the excessive increase in temperature caused by the movement of vehicles, boots are attached to the constant velocity joint and lubricant is injected into the boots. The boots maintain the lubrication and protect the constant velocity joint from sand, water, and so on. As the wheels of the vehicle rotate, the boots are acted upon by forces such as bending, compression, and tension. Additionally, self-contact occurs to boots. Therefore, their durability deteriorates over time. To prevent this problem, polychloroprene rubber was initially used however, it was replaced by thermoplastic polyester elastomers due to their excellent fatigue durability. In this study, the structural analysis of boots was conducted. The results showed the deformation patterns of the boots based on the translation and rotation of the constant velocity joint. Moreover, it confirmed the location that was vulnerable to deformation. This study can be used to potentially design high-quality constant velocity joint boots.

• Journal of Welding and Joining
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• v.25 no.4
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• pp.58-64
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• 2007

Recently, the electro-magnetic induction process has been utilizing to substitute the flame heating process in shipyard. However, few studies have been performed to exactly analyze the deformation mechanism of the heating process with mathematical model. This is mainly due to the difficulty of modeling the inductor travelling on plate during the process. In this study, heat flux distribution of the process is firstly numerically analysed with the assumption that the process has a quasi-stationary state and also with the consideration that the heat source itself highly depends on the temperature of base plate. With the heat flux, the thermal and deformation analyses are then performed with a commercial program for 34 combinations of heating parameters. The deformations obtained and heating parameters are synthesized with a statistical method to produce simplified formulas, which easily give the relation between the heating parameters and deformations. The formulas are well compared with results of experiment.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.70-75
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• 2007

Simplified mathematical formulas are presented to predict deformations during the plate forming process when the heating parameters are given. To obtain the formulas, firstly, the thermal analysis for steel plate is performed, and the thermo-mechanical analysis is followed with actual heating conditions. The analyses have been carried out by the commercial software MARC, which is programmed based on the FEM. Secondary, the results of the mechanical analysis are synthesized with their variables for a statistical approach, which results in simplified formulas. The results of the analysis are well compared with those of experimental measurements.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.1 s.151
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• pp.32-39
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• 2007

A three-dimensional finite element model has been developed to simulate the MIG P/S welding process of two aluminum plates. The finite element calculations are performed using ANSYS finite element code, which takes into account the thermal and mechanical non-linear material properties. The results of finite element analysis compared with those of experiment to show its validity in view of distortions. Parametric studies are carried out on the validated model to assess the effects of various factors on the final residual distortion. Large deformations, temperature dependent material properties are included in the model. Finally, the formulas of fitting curves of angular distortion transverse shrinkage, and longitudinal shrinkage have been proposed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.348-353
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• 2008

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.228-230
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• 2004

Samples of the aluminum alloy 3103 sheets were repeatedly deformed by ECAR up to twelve passes. Shear textures developed after the first passage of ECAR. However, the intensity of shear texture components decreased with increasing number of ECAR passages. Observations by TEM and EBSD revealed that the degree of misorientations within the deformed grains increased with increasing number of ECAR passes. Changes in textures and microstructures were hardly observed during recrystallization anneal. Upon subsequent annealing, the samples deformed by a large number of ECAR passes displayed a continuous grain growth. A higher deformation by ECAR resulted in a slower softening, which reflects the stability of ultra-fine grains against the grain growth.

• Journal of IKEEE
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• v.22 no.2
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• pp.446-454
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• 2018

In this work, we summarize the calculation processes of obtaining a scattering factor using with the equilibrium average projection scheme (EAPS), with moderately weak coupling (MWC) interaction, and obtain the line-shape formula of an electron-deformation phonon interacting system interested in the confinement of electrons by squarwell confinement potentials in quantum two dimensional system.. Through the numerical analysis, we analysis the magnetic dependence of absorption power, P(B) in several temperature and frequency difference dependence of absorption power $P({\Delta}{\omega})$, in several external field, where ${\Delta}{\omega}={\omega}-{\omega}_0$ and ${\omega}({\omega}_0)$ is the angular frequency (the cyclotron resonance frequency). The result of equilibrium average projection scheme (EAPS) in SER-MWC explains the properties of quantum transition quite well.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.494-499
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• 2003

This paper concerns the static, dynamic and thermal characteristics analysis of a high-speed spindle system for horizontal machining centers with 45mm x50,000rpm. The spindle system is designed based on the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The structural and thermal analysis models of spindle system are constructed by the finite element method. The static and dynamic characteristics are estimated based on the static deformation, modal parameter, mode shape and frequency response function, and the thermal characteristics are estimated based on the temperature rise, temperature distribution and thermal deformation. The analysis results illustrate that the designed spindle system has excellent structural and thermal stabilities

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.4
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• pp.363-369
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• 2009

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.