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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of Materials Processing
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Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 18, Issue 8 - Dec 2009
Volume 18, Issue 7 - Nov 2009
Volume 18, Issue 6 - Oct 2009
Volume 18, Issue 5 - Aug 2009
Volume 18, Issue 4 - Jul 2009
Volume 18, Issue 3 - Jun 2009
Volume 18, Issue 2 - Apr 2009
Volume 18, Issue 1 - Feb 2009
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Experimental Verification of Equivalent Drawbead Model and Application to Auto-Body Stamping Analysis
Moon, S.J. ; Lee, J.Y. ; Keum, Y.T. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 371~376
DOI : 10.5228/KSPP.2009.18.5.371
An equivalent drawbead model(EDM) for sheet metal forming analysis, which replaces complex drawbead geometries with drawbead forces in modeling the stamping dies with finite elements, is experimentally verified and applied to the numerical simulation of auto-panel stamping process. The drawbead restraining and opening forces of elliptical drawbead, circular drawbead, square drawbead, and step drawbead are obtained by performing the drawbead pulling test and compared with those of EDM and commercial code models(CCM). Better agreement with experimental measurements is found in EDM than CCM. Furthermore, the excellence of EDM is demonstrated in its application to the auto-body stamping analysis.
Study of Edge Crack Growth According to Rolling Condition in Cold Rolling
Cui, X.Z. ; Lee, S.H. ; Lee, S.J. ; Lee, J.B. ; Kim, B.M. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 377~384
DOI : 10.5228/KSPP.2009.18.5.377
The shape of edge cracking in rolling process generally occurred "V" shape. This cracking is successively generated at width edge of strip. The edge cracking is developed to center of strip during rolling process. In the results, the strip is occurred fracture, and the productivity is gone down because of the extensive production time. Accordingly, we need to control crack propagation during rolling process. But, the control of cracking is very difficult in rolling process. Previously the studies of edge cracking were mainly performed on hot rolling process. In this paper, the shape of the edge cracking in rolling was estimated according to process conditions such as initial edge crack size, reduction ratio and tension using FE-simulation and the simplicity experiments on cold rolling process.
Joint Design of Steel-Aluminum Power Steering Cylinder by using FE Analysis with Cohesive Zone Model
Lee, C.J. ; Lee, S.K. ; Ko, D.C. ; Schafer, H. ; Lee, J.M. ; Kim, B.M. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 385~391
DOI : 10.5228/KSPP.2009.18.5.385
An adhesively bonded power steering cylinder with a steel tube and an aluminum bracket was developed to reduce the weight of steering systems. To achieve the joint strength between the steel tube and of the aluminum bracket, the shape aluminum bracket re-designed by using the FE-analysis. Fracture behavior of the adhesive layer was considered by a cohesive zone model(CZM), which is based on the two-parameter fracture phenomenon with critical stress and fracture toughness. From the result of FE-analysis with CZM, re-designed power steering cylinder satisfied the desired joint strength for axial and torsion modes. And its joint strength was verified by the fracture test in each mode.
Effect of Shape Parameters of Tool on Improvement of Joining Strength in Clinching
Kim, J.Y. ; Lee, C.J. ; Lee, S.K. ; Ko, D.C. ; Kim, B.M. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 392~400
DOI : 10.5228/KSPP.2009.18.5.392
Clinching is a method of joining sheet metals together. This process can be substituted for the resistance spot welding on the joining of aluminum alloys. However, the joining strength of the clinching is lower than that of welding and riveting. The objective of this paper is to evaluate the effect of shape parameters of tools on the joining strength of the clinching and to optimize clinching tools. Twelve parameters have been selected as shape parameters on the clinching tools such as punch and die. The design of experiments (DOE) method is employed to investigate the effect of the shape parameters of tools on the joining strength of the clinching. The neck thickness and undercut of the clinched sheet metal after the clinching, and the separation load at detaching are estimated from the result of FEA using DEFORM. Optimal combination of shape parameters to maximize the joining strength of clinching is determined on the basis of the result of DOE and FEA. In order to validate the result of DOE and FEA, the experiment of clinching is performed for the optimal combination of shape parameters. It is shown from the result of the experiment that optimization of shape parameters improves the joining strength of clinching.
Effect of Mixing Condition of Raw Materials on the Thermal Properties of the Exothermic & Insulating
Kim, D.J. ; Shin, D.Y. ; Byun, S.Y. ; Wi, C.H. ; Hong, S.H. ; You, B.D. ; Oh, S.H. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 401~409
DOI : 10.5228/KSPP.2009.18.5.401
The change of the thermal properties of exothermic and insulating materials with the mixing condition of raw materials which is the most important factor for exothermic & insulating materials was investigated by using the evaluation system of the thermal properties of exothermic and insulating materials. In this study, the effect of the thermal properties of the exothermic & insulating materials such as exothermic properties, endothermic properties, insulating properties, maximum temperature of molten metal, ignition time of exothermic & insulating materials and temperature recovery time on the mixing ratio of reductant and oxidant, types of reductant, and particle sizes of reductants was examined. It could be expected to design the mixing condition of raw materials for various exothermic and insulating materials.
Analysis of Friction Coefficient Dependent on Variation of Steel Grade and Reduction Ratio in High Temperature Rolling Process
Her, J. ; Lee, H.J. ; Na, D.H. ; Lee, Y. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 410~415
DOI : 10.5228/KSPP.2009.18.5.410
Experimental and numerical studies were performed to examine the effect of material temperature and reduction ratio on friction coefficient during hot flat rolling. We carried out a single pass pilot hot flat rolling test at the temperatures range of
and measured the spread of deformed material while reduction ratio varied from 20% to 40%. Materials used in this study were a high carbon steel and two alloy steels. The dimension of specimen used in hot rolling experiment was
. We performed a series of finite element simulation of the hot rolling process to compute the friction coefficient change in terms of steel grade and reduction ratio. Results showed that temperature dependency of friction coefficient is not noteworthy but the effect of reduction ratio on friction coefficient is quite large. For high carbon steel, friction coefficient at reduction ratio of 30% is lower than that at that of 20%. Meanwhile friction coefficient at reduction ratio of 40% was one and half times large compared with that at that of 20%. The effect of steel grade on friction coefficient was significant when reduction ration was large, e.g., 40%.
Study on the Yield Locus of Aluminum Alloy Sheet Using Biaxial Cruciform Specimens
Shin, H.D. ; Park, J.G. ; Park, C.D. ; Kim, Y.S. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 416~421
DOI : 10.5228/KSPP.2009.18.5.416
The applications of the aluminum alloy sheets to the auto-body panels are dramatically increasing for weight reduction of the automobiles. However, low formability of the aluminum alloy sheet compared to the steel sheet can be obstacles in tool manufacturing processes. Therefore, many of yield criteria for the anisotropic materials such as the aluminum alloy sheet have been observed. In this study, the biaxial tensile test and FLD test for the aluminum alloy sheet are performed. The results are compared with Hill's 1948 and Hill's 1990 models by means of theoretical predictions. Finite element analysis was also performed using the proposed method for the real panel.
Measurements of Micro-Defects in the Aluminum Thixoformed Part using Computed Tomography(CT) Technology
Lee, S.Y. ; Kim, C.H. ;
Transactions of Materials Processing, volume 18, issue 5, 2009, Pages 422~427
DOI : 10.5228/KSPP.2009.18.5.422
Computed tomography(CT) has been applied to measure micro-defects in the aluminum knuckle parts manufactured by the thixoforming process. 6061 aluminum alloys were used to form knuckle samples in the semi-solid temperature after the SIMA processing of billets. Tensile specimens were cut from the different locations in a thixoformed knuckle. The size and the distribution of forming defects in tensile specimens were analyzed using CT scanning and image analysis technology before tensile tests. It has been qualitatively shown that the stress-strain curves were significantly affected by the size and the distribution of forming defects although the defect sizes lie in the range of micro-meters.