• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.91-98
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• 2004

This paper is concerned with crash analysis for an auto-body member with the forming effect. Auto-body members such as a front frame assembly are fabricated with sheet metal forming processes that induce forming histories such as the plastic work hardening and non-uniform thickness distribution. Numerical simulation is carried out with LS-DYNA3D in order to identify the forming effect on the crashworthiness. The crash analysis of the front frame assembly with the forming effect leads to a different result from that without the forming effect. Crashworthiness such as the load-carrying capacity, the crash mode and the energy absorption are calculated to investigate and identify the forming effect. It is fully demonstrated that the design of auto-body members needs to consider the forming effect for accurate assessment of the load-carrying capacity and the deformation mechanism of the formed members.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.279-280
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• 2007

In this study, it is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and forming limits of Mg alloy sheet in square cup deep drawing. Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed is very important factor for formability and forming limits. Therefore, the investigation for process variables is necessary to improve formability and forming limits. Also, the effects of strain rate and thickness transformation were studied by the experimental and FE analysis using the square cup deep drawing. The temperature, forming speed, and strain rates were investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate the formed parts were good without defects fur forming limits.

• Transactions of Materials Processing
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• v.31 no.2
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• pp.96-102
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• 2022

The multi-point dieless forming technology is one of flexible forming technologies that can form 3D curved surfaces of various shapes utilizing a lot of punch arrangements. A new technology that can simultaneously apply high-temperature forming and flexible forming technology by fusing local heating effect to such multi-point dieless forming technology was proposed in the present study. A simple local heating multi-point dieless forming apparatus was fabricated to confirm the applicability of this new technology. This equipment was designed to be used as a heat source by inserting heating cartridges in the head of the multi-point punch. Cartridges were used for all individual punches. Using the manufactured equipment, the time to raise the temperature to the target temperature and the surface temperature of the punch head part in contact with the plate were measured. In addition, forming experiments were carried out according to sheet material temperature (100 ℃, 200 ℃, and 300 ℃) to obtain forming results for each condition. The applicability and feasibility of this technology were confirmed through experimental results.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.556-561
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• 2006

Most of auto-body members are composed of stamping parts. These parts have the non-uniform thickness and plastic work hardening distribution during the forming process. This paper is concerned with the side impact analysis of the ULSAB-AVC model according to the US-SINCAP in order to compare the crashworthiness between the model with and without considering the forming effect. The forming effect is ca]ciliated by one-step forming analysis for several members. The crashworthiness is investigated by comparing the deformed shape of the cabin room the energy absorption characteristics and the intrusion velocity of a car. The result of the crash analysis demonstrates that the crash mode, the load-carrying capacity and energy absorption can be affected by the forming effect. It is noted that the design of an autobody should be carried out considering the forming effect for accurate assessment of crashworthiness.

• Transactions of Materials Processing
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• v.26 no.2
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• pp.101-107
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• 2017

Aluminum alloys are widely used in automotive industry because of their high strength-to-density ratio and excellent corrosion resistance. However, conventional cold stamping of aluminum alloys leads to low formability and excessive spring-back. To overcome these problems, Hot Forming Quenching (HFQ) is applied to manufacture automotive part using aluminum alloy. The purpose of this study is to investigate effect of forming temperature on spring-back in HFQ of T6 heat treated AA6061 sheet. In this study, hat shape forming test was adopted to evaluate spring-back characteristics according to various forming temperatures. In additions, the test was also performed with warm forming conditions in comparison with dimensional accuracy of HFQed part. The experimental results showed that dimensional accuracy of HFQed part was superior to warm formed part and amount of spring-back was decreased as forming temperature rise.

• Transactions of Materials Processing
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• v.18 no.7
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• pp.531-537
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• 2009

The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.236-241
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• 2010

The frictional behavior of bare steel sheet highly depends on surface roughness. It was investigated that the change of surface roughness of bare steel sheet due to deformation for each forming mode. The flat type friction test was done to check the effect of surface roughness change on frictional characteristics of bare steel sheet. As increasing the deformation, the Ra value was increased at stretching forming mode and drawing forming mode, however the change of Pc showed different trends. The Pc was decreased as increasing stretch deformation but increased at compression deformation. At drawing forming mode, the friction coefficient was increased as deformation was increased after initial big drop with drawing oil. As deformation was increased, the friction coefficient was decreased with drawing oil at stretching forming mode. The results show that the deformation changes the surface roughness and frictional characteristics of steel sheet but the effect depends on the forming mode.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.378-382
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• 2008

Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed and R-value is very important factor for formability and forming limits and deep drawing. It is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and R-value of Mg alloy sheet in round cup deep drawing. Therefore, the investigation for process variables is necessary to improve formability and forming limits and deep drawing. Also, the effects of strain rate and drawbility were studied by the experiment. The temperature, forming speed, and strain rates and R-value are investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate and R-value the formed parts were good without defects for forming limits and deep drawing.

• Transactions of Materials Processing
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• v.21 no.7
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• pp.403-411
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• 2012

The aim of this study was to predict the results of superplastic forming on magnesium alloy, by considering the grain growth using numerical simulations. Superplastic behavior of AZ31 alloy was investigated through a set of uniaxial tensile tests that cover the forming temperatures ranges from 375 to $450^{\circ}C$. All the material parameters in the model, which consists of a constitutive equation and a grain growth equation, were determined. The model was used in the finite element analysis for uniaxial tensile tests and superplastic blow forming, through a user-subroutine available within ABAQUS. From this study, the effect of grain growth during forming was evaluated. The results show that it is essential to include the effect of grain growth in predicting the behavior during superplastic forming of this magnesium alloy.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03a
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• pp.172-184
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• 1996

Superplastic forming of thin sheet into complex shape is an important manufacturing process especially in aerospace industry. The main interest in modeling the superplastic forming process is to predict the forming pressure cycle to maintain optimum strain rate and the resulting thickness distribution. Many researchers have attemped to model superplastic forming using the various techniques including finite element method. But in most of their researches have disregarded the strain hardening effect which which occurs in several superplastic materials. In this study ABAQUS finite element code was used for prediction of process variables for axisymmetric cup forming of Supral 100 and 7075Al alloys considereing strain hardening. The performance of numerical results were compared with the experimental results.