• Transactions of Materials Processing
• /
• v.11 no.5
• /
• pp.457-464
• /
• 2002

A finite element inverse analysis is utilized to consider forming effects of an S-rail on the assessment of the crashworthiness with small amount of computation time. A crash analysis can be directly performed after the inverse simulation of a forming process without a smoothing or remeshing scheme. The direct mesh mapping method is used to calculate an initial guess from a sliding constraint surface that is extracted from the die and punch set. Analysis results demonstrate that energy absorption of structures is increased when simulation considers forming effects of thickness variation and work hardening. The finite element inverse analysis is proved to be an effective tool in consideration of forming effects for the crash analysis.

• Proceedings of the KWS Conference
• /
• 2005.06a
• /
• pp.91-93
• /
• 2005

Forming sheet metal by laser-induced thermal stresses (laser forming) has been extensively studied, and the research has focused on two-dimensional geometries using a multi-pass straight line scan. Recently there came out some useful studies or three-dimensional laser forming which is applied to doubly curved shapes. The task of 3D laser forming sheet metal is to determine a set of process parameters such as laser scanning paths, laser power and scanning speed that will make a given shape. New method for laser forming of a doubly curved surface by using geometrical information was proposed and verified by experiments. This method shows good performance in the sense of calculation time and accuracy compared to the inherent strain method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.419-422
• /
• 2005

Many process parameters have an effect on the auto-body panel forming process. A well-designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented in this paper, the one-step approach by using a finite element inverse method will be introduced to predict the initial blank shape the developed program is applied to auto-body panel forming.

• Transactions of Materials Processing
• /
• v.11 no.6
• /
• pp.503-512
• /
• 2002

The drawbead is used to control material flow into the die during the binder wrap process and the stamping process in the sheet metal forming process. Since the dimension of drawbead is relatively small in comparison with the typical dimensions, it is difficult to include drawbeads in finite element analysis of the sheet metal forming process. It is because the mesh system has to be fine enough to describe the drawbead and the computation time is drastically increased. In this paper, simulation of drawbead forming has been carried out to obtain the equivalent boundary conditions in the binder wrap process and the stamping process. In order to investigate the effect of various die geometries, parameter studies are performed with the variation of parameters such as the blank length, the drawbead depth, the drawbead radius, the inclination of die and the friction coefficient.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.387-390
• /
• 2008

Electromagnetic forming (EMF) technology, which is one of the high speed forming methods, has been used for the forming process in various industry fields. Numerical approach by finite element simulation of the EMF process is presented in this study. The implicit code is used to obtain the numerical model of the time-varying currents that are discharged through the coil in order to obtain the transient magnetic forces. In addition, the body forces generated in the workpiece are used as the loading condition to analyze deformation of thin sheet metal workpiece using explicit code. Numerical approach for a dimpled shape by EMF process is carried out and the simulated results of the dimpled shape by EMF are reviewed in view of the deformed shape and formability evaluation.

• Transactions of Materials Processing
• /
• v.32 no.6
• /
• pp.303-310
• /
• 2023

Electrohydraulic forming(EHF), one of the high-speed forming method, can supplement the weak point of previous forming process such as deep-drawing and electromagnetic forming. Indeed, EHF is time-consuming process during installing wire before experiment that hard to apply to industry. In this research, applying wireless electrode, the formability of SUS430 sheet was compared through EHF experiments using wire-installed electrode and the other, wireless. Although the power was a little lacking, the advantages of the experiment using wireless electrode could be confirmed with checking the optimal location of electrodes where the plasma is generated and comparing free-bulging height depending on former and later condition of electrodes with performing several single and multistage experiments for same voltage, 6 kV.

• Transactions of Materials Processing
• /
• v.9 no.3
• /
• pp.293-303
• /
• 2000

Recent developments of Fe technology make it possible to apply CAD/CAE/CAM techniques successfully to the stamping die design among the automotive parts industries. Those successful applications are greatly attributable to the development of commercial S/W. Up to now most commercial S/W for the analysis of sheet metal forming is based on the dynamic explicit algorithm. The main characteristics of dynamic explicit algorithm is that there is no convergence problem if the time increment is taken less than the stability limit. The stability of the analysis is guaranteed in the commercial code, since the adequate time increment is computed from the so called "Courant Condition". However excess computing time is often pointed out in the dynamic explicit analysis according to the characteristics of process parameters taken. In the study, various parameters that may affect the stability and the method how to improve computational efficiency of analysis have been investigated.estigated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.06a
• /
• pp.16-27
• /
• 1997

A semi-solid forming has a lot of advantages compared to the die casting, squeeze costing and convenctional forging, therefore, semi-solid forming process are now becoming of industial interest for the production of metal components and metal matrix composites. However, the material behaviour in the semi-solid temperature range is not sufficiently known although it controls the whole process through forces and geometry evolutions bcause the behaviour of metal slurries is complex. The semi-solid materials(SSM) fabricated under electric-magnetic stirring condition is necessary to be applicate in forming process. A reheating conditions were studied with the reheating time, holing time and reheating temperatures. The microstructure of SSM (which specimen size:d 40${\times}$i60) on condition of heating time 10min and heating temperature 590$^{\circ}C$ is most globular and finest one. The microstructure of SSM(specimen size:d75${\times}$i60) reheated under the three step reheating conditions is most globular and finest.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.34 no.3
• /
• pp.32-37
• /
• 2002

The paper mill wastewater actually generating bulking was used to apply to the spot. Batch and continuous type pilots were used in this study. Optimal time after propagating generation of activated sludge in aeration basin by adding Hoc forming microorganism was 24 and 36hours while optimal time of activated sludge in original aeration basin was 60hours. Showing the difference of sedimentation velocity at 7th day after operating a pilot continuously, SV30 was decreased to 50% at 13th day. COD value in aeration basin with floe forming microorganism was 35mg/L while COD value in original aeration basin was 52mg/L. It was indicated that application of Hoc forming microorganism can control the bulking of paper mill wastewater by shortening of recovery time and improving of pollution removal efficiency.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.4
• /
• pp.10-17
• /
• 2000

The change of fiber length, freeness, initial forming drainage velocity, specific filtration resistance, final drainage time and wet web dryness were measured to investigate the effect of the refining load on the drainage characteristics of pulp. The arithmetic average fiber length after refining with higher refining load was shorter than that obtained with lower refining load. Higher refining load decreased initial forming drainage velocity, final drainage time and wet web dryness. The refining load also affected the relationship between freeness and specific filtration resistance, initial forming drainage velocity, final drainage time. It was found that the specific filtration resistance is better than freeness to predict the drainage characteristics of pulp and the wet dryness.