• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.03b
• /
• pp.30.1-33
• /
• 1999

Finite element simulation with experimental analysis of Taguchi's orthogonal array was carried out to know the effects of material and forming parameters on the cup earing and skewness. It was revealed that the planar anisotropy was the most influencing factor in the cup ear formation whereas blank holding force and material properties such as strength and thickness deviation at the coil edge had a relatively high effect on the cup skewness.

• Transactions of Materials Processing
• /
• v.9 no.6
• /
• pp.561-566
• /
• 2000

Recently, the hydroforming technology has been recognized as a general technique in manufacturing industry, especially in automotive industry. Hydroforming is applied to increase strength, and to decrease weight, cost and parts. Hydroforming is based on the inflation of, for Instance, a tube, coupled with axial or radial compression and by subsequent expansion and sizing against the die wall. Expansion, axial feeding, calibration are important parameters in this process. In this paper, the effects of various parameters such as internal pressure, axial feeding and friction on hydroforming of automotive bumper rail have been considered.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.223-226
• /
• 1995

A three-dimensional elastic-plastic finite element analysis using the explicit time integration method has been performed for the characterization of theimpact forming machines. The block upsetting using a forging hammer has been analyzed. The effects of machine type, work capacity of equipment and the mass ratio in an anvil-type hammer have been studied through the analysis.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
• /
• v.6 no.1
• /
• pp.47-65
• /
• 2000

In order to investigate antitumor and immune response effect by Hyangsapyungwisan after Sarcoma-180 cells and methotrexate were treatred each other, the extract of Hyangsapyungwisan was orally administered to ICR mice for 14 days. To evaluate the effects of the Hyangsapyungwisan, 50% inhibition concentration($IC_{50}$), mean survival days, tumor weight for antitumor effects, hemagglutinin titer, hemolysin titer, rosette forming cells, natural killer cell activity and productivity of interleukin-2 for immune responses measured in ICR mice. The results were summarized as follows: 1. Mean survival time in Hyangsapyungwisan-treated group was slightly prolonged, as compared with control group(13.46%). 2. On the MTT assay, cell viability was significantly inhibited by $5{\mu}g/well,\;2.5{\mu}g/well,\;1.25{\mu}g/well,\;and\;0.625{\mu}g/well$ of Hyangsapyung-wisan concentration inhibited cell viability significantly. $IC_{50}$ for cell viability was $11.59{\mu}g/well$. 3. Tumor weight in Hyangsapyungwisan treated group was depressed, as compared with the control group(p<0.05). 4. Hemagglutinin titer in Hyangsapyungwisan-treated group was slightly increased with no significance, as compared with the control group. 5. Hemolysin titer in Hyangsapyungwisan-treated group was silightly increased, as compared with the control group(p<0.05). 6. Rosette forming cells in Hyangsapyungwisan-treated group was silightly increased, as compared with the control group(p<0.05). 7. Naural killer cell activity in Hyangsapyungwisan-treated group was significantly increased(p<0.05). 8. Production of interleukin-2 was significantly increased(p<0.05). According to the above results, Hyangsapygwisan had prominent antitumor effects, and enhance both cellular and humoral immunity in mice.

• Transactions of Materials Processing
• /
• v.17 no.7
• /
• pp.511-516
• /
• 2008

A drawbead die for the experimental determination of drawbead forces was newly introduced in this paper. While the conventional Nine's drawbead die inevitably includes effects of a blank holding force on the measured drawbead forces, the new drawbead die excludes it by removing the blank holder contact in the dieface. Therefore, the new drawbead die can provide more realistic drawbead forces without considering somewhat arbitrary effect of blank holder with the computational procedure of forming process. The drawbead opening force and restraining force obtained by adopting the two experimental dies were compared for the validation of accuracy in the FEM simulation of automotive fender forming process. The compared section strains and draw-ins confirmed that the present drawbead die provides better drawbead forces for an accurate FEM simulation of sheet metal forming process.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.22 no.1
• /
• pp.111-120
• /
• 1998

This paper is the first one of two-parted research efforts focusing on the modeling of rubber pad forming process. The rubber pad, driven by the pressurized fluid during the forming process, pushes the sheet metal to solid tool half and forms a part to final shape. In this part of the paper, a numerical procedure for the FE analysis of the rubber pad deformation is presented. The developed three-dimensional FE model is based on the total Lagrangian description of rubber maerial characterized by nearly incompressible hyper-elastic behavior under a large deformation assumption. Validity of the model as well as effects of different algorithms corresponding to incompresibility constraints and time integration methods on numerical solution responses are also demonstrated.

• Transactions of Materials Processing
• /
• v.15 no.7 s.88
• /
• pp.512-517
• /
• 2006

In this paper, the cold extrusion process for internal spline forming using a thin and long tube has been analyzed by using a rigid plastic finite element code. The internal spline consists of 10 tooths. The cold extrusion process has been focused on the comparisions of load-stroke relation and filling states of the teeth according to design parameters. The design parameters involve extrusion ratio, extrusion angle and friction factor. The internal spline forming can cause the buckling and folding during the cold extrusion process because of using a thin and long tube. The optimum design parameters have been obtained through rigid-plastic finite elements analysis. The extrusion ratio and extrusion angle have great effects on the deformation characteristics of the cold extrusion process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.06a
• /
• pp.75-86
• /
• 1996

Three-Dimensional finite element analysis is performed using PAM-STAMP for design evaluation of automotive back door inner panel die. Gravity process by blanks own weight, binder-wrap process, and drawing process in the forming operations are sequentially simulated with Virtual Manufacturing Method. The most valuable result in this research is that 3-D FEM analysis can be applied to the design evaluation of draw die in the die try-out, though effects of mesh size and drawbead resistance force on the numerical accuracy are much sensitive. For the intensive application to draw-die design and try-out, the experimental know-hows about the forming variables such as friction coefficient, punch velocity, drawbead force, etc are necessary.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.439-442
• /
• 2003

This study presents a new computational model to analyze the grain deformation in a polycrystalline aggregate in a discrete manner and based directly in the underlying physical micro-mechanisms. As a result, specific characteristics have to be considered for the numerical analysis. The grains and grain boundary elements are introduced to model individual grains and grain boundary facets, respectively, to consider the size effects in the micro forming. The constitutive description of the grain elements accounts for the rigid-plastic and the grain boundary elements for elastic relationships. The capability of the proposed approach is demonstrated through application of grain element and grain boundary element in the micro forming.

• Transactions of Materials Processing
• /
• v.21 no.3
• /
• pp.186-194
• /
• 2012

Hot stamping is a forming method that offers various advantages such as superior mechanical properties, good formability, and very small springback. However, relatively large-sized parts, such as front pillars, exhibit poor formability when hot stamped due to the limited material flow and thickness reduction imparted by the process. This reduction in thickness can also lead to cracks. One of the reasons is the relatively high friction between the sheet and the die. In this study, in order to obtain the optimal conditions for hot stamping of front pillars, various process parameters were studied and analyzed using the sheet forming software, J-STAMP. The effects of various parameters such as the die structure, blank shape, blank holding force, punch speed, clearance(upper and lower dies) and distance block were analyzed and compared.