• Transactions of Materials Processing
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• v.16 no.7
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• pp.516-520
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• 2007

As the springback of sheet metal during unloading nay cause deviation from a desired shape, accurate prediction of springback is essential for the design of sheet stamping operations. On the removal of the applied load the specimen loses its elastic strain by contracting around the contour of the block, the radius $\rho$ can be determined by the residual differential strain. Therefore in this study the springback estimated by the residual differential strain is experimentally validated through the comparison with those obtained by U-bending test. The springback characteristics of two analytical models are also estimated at various processing conditions such as thickness, curvature of radius and drawing strain. The model based on residual differential strain has an applied transition strain where the springback undergoes a dramatic decrease. Both models show that springback decreases with increased strip thickness and with decreased radius of curvature. For no applied tension, the model based on residual differential strain predicts more springback as compared to the moment based model.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1853-1860
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• 1992

The plane-strain stamping process is analyzed by a forming energy minimization method in order to obtain forming load, slip length and strain distribution in each step of punch stroke. All the developed programs are integrated into total CAD/CAE SYSTEM for the purpose of the practical usage in die design. The computed strain distribution and the amount of draw-in are compared with those of the actually developed panel It is found that there is a good agreement between theoretical and experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.38-47
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• 1996

Sectional analysis program for plane strain or axisymmetric geometry of aluminum alloy sheet metals was developed. For modeling the anomalous behavior of aluminum alloy, Barlat's strain rate potential and Hill's 1990 non-quadratic yield theory arranged under the plane stress assumption were employed. 2-D rigid-viscoplastic FEM formulation based on the bending-augmented membrane theory was derived, solving simultaneously force equilibrium as well as non-penetration condition. Isotropic hardening law was also assumed for yielding behavior. To verify the validity and availability of the developed program, 2-D stretch/draw forming process for plane strain geometry and cylindrical cup deep drawing process for axisymmetric geometry were simulated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.703-704
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• 2012

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.71-78
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• 2007

Stainless steel is very famous for using of industrials structure and joint elements. Stainless steel wire drawing is one of the most ancient crafts. But there's not any standard size of tapered die during tile drawing. This paper was studied die angle and dimension of whole die by using AFDEX drawing simulator. Stress, metal flow and strain rate was analyzed by AFDEX tools during the wire drawing. So optimum data of during dies was taken from them. Simulation data was correspond with experimental data. The results of the optimum dies are shown that (1) Reduction angle is $13.8^{\circ}$ (2) Bark relief angle is $20^{\circ}$ (3) Bearing length is 0.7975mm (4) Bearing dia is 0.2393mm The research of the optimum result when the make dies is connected an enterprise. After researching, I hope that indirection effect creation make development situation of the manufactural technical, practical application of the other die size by the detail data, utility factor and economical efficiency.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.49-57
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• 2012

It is difficult to estimate the properties of multilayered sheet because they are composed of one or more different materials. Plastic deformation behavior of the multilayered sheet is quite different as compared to each material individually. The deformation behavior of multilayered sheet should be investigated in order to prevent forming defects and to predict the properties of the formed part. In this study, the mechanical properties and formability of stainless steel-aluminum-magnesium multilayered sheet were investigated. The multilayered sheet needs to be deformed at an elevated temperature because of its poor formability at room temperature. Uniaxial tensile tests were performed at various temperatures and strain rates. Fracture patterns changed mainly at a temperature of $200^{\circ}C$. Uniform and total elongation of multilayered sheet increased to values greater than those of each material when deformed at $250^{\circ}C$. The limiting drawing ratio (LDR) was obtained using a circular cup deep drawing test to measure the formability of the multilayered sheet. A maximum value for the LDR of about 2 was achieved at $250^{\circ}C$, which is the appropriate forming temperature for the Mg alloy. Fracture patterns on a circular cup and thickness of formed part were predicted by a rigid-viscoplastic FEM analysis. Two kinds of modeling techniques were used to simulate deep drawing process of multilayered sheet. A single-layer FE-model, which combines the three different layers into a macroscopic single layer, predicted well the thickness distribution of the drawn cup. In contrast, the location and the time of fracture were estimated better with a multi-layer FE model, which used different material properties for each of the three layers.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.127-132
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• 2003

In a today industry, the welding is doing a many portion in structure manufacture. This study is simulated heat of heat-effected zone and researched a mechanical properties and ultrasonic characteristic in used the SS400 and the STS304. As the result mechanical properties of steel that become drawing decreased because of remaining stress by strain gardening according as simulated heat temperature rises, but according as temperature rises in material that do simulated heat after have done annealing, mechanical propensity was improved. The velocity and attenuation become different by effect of remaining stress than effect of material internal microstructure in ultrasonic wave test. In the case of STS304, there was change in mechanical properties by effect that is by strain hardening, but there was no change in material that simulated heat after annealing. When become drawing in ultrasonic waves test, according as simulated heat temperatures rise, change of attenuation coefficient is looked, but material that simulated heat after annealing was no change almost both the volocity and attenuation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.231-234
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• 2009

The effects of annealing temperature and time on mechanical properties and microstructures were already investigated in cold drawn pearlitic steel wires. During annealing, the increment of the tensile strength at low temperatures found to be due to age hardening, while the decrease in the tensile strength at high temperatures was attributed to age softening, involving the spheroidization of lamellar cementite and recovery of lamellar ferrite. Since Between increase of tensile strength and the occurrence of the delamination would be closely related to the dissolution of cementite, the increase of drawing strain by lower annealing temperature caused the between higher tensile strength and the easier occurrence of the delamination in cold drawn pearlitic steel wires.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2435-2440
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• 2012

In this paper, Solidworks was used to do a conceptional design of an box of an electric saver in order to manufacture an electric saver having a different performance and model. Based on this, analysis was made considering weight concentrated on an box. 3-dimensional finite element analysis code, ANSYS was applied to obtain stress, strain and deformation in order to secure durability and these data was reflected to a detailed drawing.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.95-103
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• 1992

The plane strain analysis for simulating the stretch/draw forming operation with an arbitrarily-shaped tool profile is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The linear line elements are used for depicting the formed sheet, based on membrane approximation. The FEM formulation is tested in the sections of automotive inner panel and two-side draw-in. Not only the excellent agreement between measured and computed strains is obtained in the stretched section, but also the numerical stability of formulation is verified in the draw-in section.