• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.460-467
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• 1998

The investigation deals with the manufacturing process design and deformation analysis for seamless pressure vessels Axisymmetric multistage deep drawing is a complex and important sheet metal forming process in the industry. In this study the process design for large size cylindrical shells with various thickness is performed and a general guideline for forming process design of pressure vessels will be suggested. Thus in this paper for the verification of the forming process design the forming analysis of pressure vessels will be carried out by PAM-STAMP which is on the basis of finite element analysis. In this case the formability of pressure vessels is evaluated using the results of computer simulation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.96-102
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• 2021

Hexagonal bolt, nut, fittings, and high-pressure valves with special alloy play an important role in many industrial products. Numerical analysis was conducted to obtain data for designing a new drawing system. This study aims to predict the rolling force of the new drawing system compared to that of the established drawing system. The rolling force of the new drawing system was predicted using numerical analysis by assuming that it is in proportion to deformation. The rolling forces of Mo, Ti, and W were approximately 1.4, 0.5, and 2.5 times those of SUS. Because the values of ultimate strength of special alloys were more close to numerical analysis, the values of ultimate strength could be used to predict the rolling force of the new drawing system without numerical analysis in field.

• Transactions of Materials Processing
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• v.10 no.2
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• pp.144-150
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• 2001

Tool design is introduced in a multi-stage rectangular cup drawing process with the large aspect ratio. Finite element simulation is carried out to investigate deformation mechanisms with the initial tool design. The analysis reveals that the difference of the drawing ratio and the irregular contact condition produces non-uniform metal flow to cause wrinkling and severe extension. For remedy, the modification guideline is proposed in the design of the tool and process. Analysis results confirm that the modified tool design not only improves the quality of a deep-drawn product but also reduces the possibility of failure.

• Transactions of Materials Processing
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• v.10 no.5
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• pp.411-417
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• 2001

A Comparative study on deep drawing of clad sheet is carried out to investigate the forming characteristics and the effectiveness of modified finite element analysis. An elasto-plastic finite element analysis Is developed to analyze the forming of clad sheet using explicit scheme and layered shell. Axisymmetric deep drawing of stainless clad metal sheet is performed and thickness distribution is obtained. The corresponding finite element analysis shows good agreement with the results. Some disagreement can be explained by the assumption of shell element and the complexity of deformation of clad sheet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1810-1818
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• 1996

A new finite elemetn approach is introduced for direct prediction of bland shapes and strain distributions from desired final shapes in sheet metal forming. The approach deals with the geometric compatibility of finite elements, plastic deformation theory, minimization of plastic work with constraints, and a proper initial guess. The algorithm developed is applied to cylindrical cup drawing, square cup drawing, and fron fender forming to confirm its validity by demonstratin reasonable accurate numerical results of each problems. Rapid calculation with this algorithm enables easy determination of various process variables for design of sheet metal forming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.121-124
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• 2002

This paper resents a virtual forming system to simulate deep drawing process for stress-strain information by utilizing virtual system designed using Virtual Reality Modeling Language (VRML) and computer aided analysis (CAE) tool. The CAE tool to calculate stress, strain, and deformation is designed using Finite Element Method. Stress distributions and deformation profiles as well as the operation of forming machine can be simulated and visualized in the web. The developed system consists of three modules, input module, virtual forming machine module, and output module. The input nodule was designed using HTML and ASP. The input data for FEM calculation is directed to the forming machine module for calculation. The results from the forming machine module can be visualized through output module as well as the forming process simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.121-130
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• 1998

In order to analyze the forming characteristics of laser welded tailored blanks, laser welded blanks of different thickness and strength combinations were prepared and tensile, stretching, stretch flanging and deep drawing tests were done. The tensile elongation perpendicular to the weld line, stretching and stretch flanging formability decreased with increasing the deformation restraining force (strength ${\times}$ thickness) ratio between two welded sheets. The tensile elongation along weld line reached a value above 90% of the single sheet's elongation. Stretch flanging formability was reduced to approximately 10% of the single sheet value when the deformation restraining force ratio between two welded sheets was increased to two. Weld line movement of deep drawing test specimens was also affected by the strength ratio of the combined sheets, the weld line location and forming conditions. In all forming modes of tailored blanks, excessive weld line movement resulted from strain concentrations at the weaker sheet and resulted in fracture of the weaker side.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.861-869
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• 2018

To determine the origin of the inhomogeneous microstructure and texture observed in drawn and annealed high purity copper wires, two kinds of drawing process conditions and their influence was investigated. The regular condition, based on a symmetric die, and a condition designed intentionally to produce an inhomogeneous shear deformation using an asymmetric die were employed. The difference in intensity of <111>-<100> distributed texture between the two wires confirmed that the wire drawn under the asymmetric die condition experienced a higher amount of shear deformation. The extensive shear strain in the wire drawn under the asymmetric die condition gave rise to inhomogeneous primary and secondary recrystallization behavior. After annealing at $200^{\circ}C$, grains with <100> texture, which were larger than the surrounding recrystallized grains, were extensively present on one half circle of the wire drawn under the asymmetric die condition, while larger grains with <100> were sparsely observed around the middle region of the wire drawn under the regular condition. Interestingly, the area where the larger grains with <100> texture existed was identical to the area where the high shear strain occurred during drawing in both wires. During annealing at $400^{\circ}C$, grains with <112> texture started to grow abnormally at the center of both wires as a result of secondary recrystallization. After annealing at $900^{\circ}C$ grains with <112> due to secondary recrystallization occupied the entire region of the wire drawn under the regular condition. On the other hand, in the wire drawn under the asymmetric die condition and then annealed at $900^{\circ}C$, the <100> oriented grains as a result of the normal grain growth of the larger <100> grains which were observed after annealing at $200^{\circ}C$, coexisted with the abnormally grown <112> grains. These results indicate that dynamic recrystallization induced by the shear strain during drawing plays an important role in the inhomogeneity of the microstructure and texture of wires after annealing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.06a
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• pp.173-184
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• 1994

A method of obtaining deformation severity of axisymmetric shape deep-drawn products was developed. Strain states of products produced by single or multi-stage drawing were predicted by using finite element analysis. This method used minimization of potential energy between the known shape of final product and the unknown in initial blank. And that was done numerically by nonlinear finite element method. Deformation theory of plasticity was used for practical purposes. From predicted strain states of drawn parts, deformation severity was found by using forming limit diagrams.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.301-301
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• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.