• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1569-1572
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• 2003

Meshfree approximations exhibit significant potential to solve partial differential equations. Meshfree methods have been successfully applied to various problems which the traditional finite element methods have difficulties to handle, including the quasi-static and dynamic fracture. large deformation problems, contact problems, and strain localization problems. A meshfree method based on the reproducing kernel particle approximation(RKPM) is applied to sheet metal forming analysis in this research. Metal forming examples, such as stretch forming and flanging operation, are analyzed to demonstrate the performance of the proposed meshfree method for largely deformed elasto-plastic material.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.253-257
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• 2001

This study reveals the sheet metal working with multi-forming type ultra precision process. They require analysis of many kinds of important factors, i.e. theory and practice of metal press working and its phenomena, die structure, machining condition for die making, die material, heat treatment of die components, know-how and so on. In this study, we designed and constructed a multi-forming ultra precision progressive die as a bending and drawing working of multi-stage and performed through the try out for thin sheet metal. This part I of papers related to the analysis of production part and strip process layout design through the metal forming simulation by DEFORM and IDEAS.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.546-551
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• 1997

In sheet metal forming, since the surface area of workpiece is apparently larger than the volume of it, the surface condition of the sheet metal is much varied. The formability of sheet metal is decided by the forming limit and the macroscopic suface defect as like fracture and wrinkle, and microscopic asponent, The factors affected in forming limit are stain herdening exponent, strain-rate scnsitivity exponent, anisotropic coefficient. The increasing of surface roughness is decresed the forming limit curve. It is known that the greater plastic deformation the more surface roughness by Kienzle, Osadaka. The purpose of this study is to investigate the influences of surface roughness in a uniaxial tension and the traperzoidal-shaped box drawing.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.165-166
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• 2010

• 한국정밀공학회지
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• 제33권4호
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• pp.247-255
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• 2016

Sheet metal-forming processes such as stamping, deep drawing, bending, shearing, hydroforming, hydromechanical deep drawing, rubber forming, and incremental forming have been widely used in the automotive, aircraft, and ship-building industries. With the expansion of the automotive industry, research on these processes has been remarkably developed in Korea since the 1980s. Here, we review the history of this research as well as recent trends in sheet metal-forming processes. This overview focuses specifically on the results of research in Korea and on the works of Professor D.Y. Yang, in honor of his retirement.

• 소성∙가공
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• 제17권8호
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• pp.643-648
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• 2008

Ultra-thin sheet metal forming techniques are required in precision forming of miniaturized and integrated products. In order to manufacture a good quality and low cost ultra-thin sheet metal products, a highly precise high-speed press is needed. The precision of a press is related with its vibration characteristics during pressing operation. This study evaluated the vibration characteristics of a proposed press design using computer simulation. The analysis compares the static deformation characteristics of the slide and the slide motion for the metal forming of an ultra-thin sheet of thickness less than 0.1mm. Further, in order to minimize the vibrations during high speed pressing operation, revolution balances of the eccentric shaft and the balance weight device is also considered. Finally, modal analysis is used to characterize the natural frequency of vibration of the press.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.62-65
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• 2002

A dieless forming system which consists of hydraulic punch elements and elastomer/fluid pads, was developed for sheet metal forming. 2-D curved surface forming was carried out using open-loop, closed-loop, and repeated forming method. Closed-loop exhibited higher decision than open-loop forming. Repeated forming also showed reduced spring back and possibility of high precision.

• 한국정밀공학회지
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• 제15권9호
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• pp.117-126
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• 1998

For investigating rubber pad sheet metal forming process, the rubber pad deformation characteristics as well as the contact problem of rubber pad-sheet metal has been analyzed. In this paper, the behavior of the rubber deformation is represented by hyper-elastic constitutive relations based on a generalized Mooney-Rivlin model. Finite element procedures for the two-dimensional responses, employing total Lagrangian formulations are implemented in an implicit form. The volumetric incompressibility condition of the rubber deformation is included in the formulation by using penalty method. The sheet metal is characterized by elasto-plastic material with strain hardening effect and analyzed by a commercial code. The contact procedure and interface program between rubber pad and sheet metal are implemented. Inflation experiment of circular rubber pad identifies the behaviour of the rubber pad deformation during the process. The various form dies and scaled down apparatus of the rubber-pad forming process are fabricated for simulating realistic forming process. The obtaining experimental data and FEM solutions were compared. The numerical solutions illustrate fair agreement with experimental results. The forming pressure distribution according to the dimensions of sheet metal and rubber pads, various rubber models and rubber material are also compared and discussed.

• 한국정밀공학회지
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• 제23권1호
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• pp.152-158
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• 2006

The AutoForm previously used the membrane element and it accomplished sheet metal forming analysis. The membrane analysis has been widely applied to various sheet metal forming processes because of its time effectiveness. However, it is well-known that the membrane analysis can not provide correct information for the processes which have considerable bending effects. In this research experimental results were compared with the analysis results obtained by using the shell element which is applied newly in the AutoForm commercial software. The shell element is a compromise element between continuum element and membrane element. The Finite element method by using shell element is the most efficient numerical method. From this research, it is known that FEA by using shell element can predict accurately the problems happened in actual experimental auto-body panel.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.903-904
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• 2010