• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.128-134
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• 2013

High bending collapse performance (maximum resistance force and mean resistance force) of body center pillar is an important design target for vehicle safety against side impact. In this study, effect of the upper section shape and the thickness of outer reinforcement on bending collapse performance was investigated for the center pillar of a large passenger car. First, through bending collapse analyses using simple models with uniform section, an optimized center pillar upper section was chosen. Next, bending collapse performance for various models of the actual center pillar with changing the thickness of outer reinforcement were analyzed. The finally designed model showed distinctive enhancement in bending collapse performance nearly without weight increase.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.38-47
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• 2000

Recently, finite element method has been used as an effective tool in the design process of sheet metal forming. In the present study, an implicit method and an explicit method have been developed for 2D analysis and 3D analysis, respectively, and applied to several processes including plane strain draw bending and TWB sqaure cup drawing. Also, commercial codes are used for geometrically complex problems, such as tube hydroforming, "L" cup deep drawing and side frame forming. In this paper, basic formulations used in the methods are introduced and results obtained from the applications are discussed.discussed.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.53-59
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• 1999

Recently, Tailor Welded Blank (TWB) is widely used in automotive industry since the transformation characteristic of its material can be changed. However, clearance between welding surfaces becomes the important factor which affect the quality of the laser weld, causing difficulties in preparing the sheet. The objective of this paper is to systematically evaluate the effects of previously presented fracture criterion and shearing condition on precise mechanical shearing simulation result. For this purpose, a parametric study was peformed to investigate the effect of finite element size and fracture criterion on simulation result. Also, in order to predict the optimum shearing condition, effect of shearing conditions such as clearance and punch radius on the shear plane shape was evaluated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.159-162
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• 2000

Wrinkles and shape distortions are generated during the forming of B-pillar(or center pillar) which is a component of the automobile side-frame. The stretch flanging modes at the joining part of the B-pillar and the roof-rail or the side-still give rise to forming problems when taior-welded blanks are applied to the side-frames. The authors simplified B-pillar lower part to T shaped section to investigate the forming behaviors. Three of die step locations and two of blank types were tested to show the effects of weld line locations and edge conditions on he forming of tailor welded blanks. The heights of body wrinkles and the strain distribution in the stretch flanged area were measured and compared.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.31-36
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• 1997

Various methods of finite element modeling for welded part are examined and the stamping simulation of automotive body is presented by using the explicit finite element code PAM-STAMPTM. The process of stamping simulation is suggested step by step, and then the gravity, binder wrap, forming, trimming and springback of front door inner are analyzed. It shows good agreements with real product in the aspects of deformed shape and failure area. The door inner with laser-tailor welded blank is simulated, in which deformed shape, movement of welde line and formability are predicted.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.65-71
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• 1997

Computer simulations and test trials are carried out to get the optimal conditions about the stamping die design of the tailor laser welded automotive door inner. Firstly, the stamping process including gravity deflection, bead calibration, binder wrap, forming and spring back, are analyzed by the computer simulation. The results of simulation shows good correspondance with those of test trial under the same conditions. The variables of parametric study which will be investigated in the simulation and test trials, are determined form the results of the first run. The formability under the various conditions is evaluated, which are the initial postion of blank, blank holding force, corner radius and the shape of drawbead. Finally, well controled sound product without fracture, wrinkling and excessive weldline movement is obtained.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.429-436
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• 1999

In sheet metal forming , forming limit diagram is very important to design and analyze of sheet metal forming process. Recently tailor welded blanks of different thickness and different material and strength combinations are used widely in automobile industry to reduce car manufacturing cost. In order to analyze the forming characteristics of tailored welded blanks, we have investigated the forming limit dia-grams for 3 kinds of different material using mash seam and laser welding experimentally and dis-cussed for the characteristics of forming for tailor welded blanks. It is concluded that forming limit dia-gram for the different material combination TWB locates between FLD of the thinner base material sheet and the thicker ones.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.73-79
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• 2009

In order to investigate the formability of friction stir welded(FSW) tailor welded blanks(TWB) with respect to the base material's directional combination, aluminum alloy AA6111-T4 sheets were welded with three different conjoining types: RD-RD, TD-RD and TD-TD. Here, RD and TD represent rolling and transverse directions, respectively. For experimental formability study, three tests with gradual complexity were performed: the simple tension test with various weld line directions for uni-axial elongation, the hemisphere dome stretching test for biaxial stretching and the cylindrical cup deep drawing test. As a result, all three forming tests showed that RD-RD type samples exhibited the best formability, while TD-TD type sheets showed the least formability performance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.151-155
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• 2001

The purpose of this study is to investigate the weldline movement of the laser welded sheets during the warm deep drawing process. For this investigation, Five steps of temperature ranges, from room temperature to $200^{\circ}C$, and two kinds of thickness combination, 0.8 mm${\times}$1.2 mm and 0.8 mm${\times}$1.6 mm SCP1 material sheets, were adopted. Also, the numerical analysis using the PAM-STAMP has been carried out with the same models as the specimens. As a result the higher temperature was adopted, the less weld-line movement was observed.

• Journal of Korea Technology Innovation Society
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• v.6 no.2
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• pp.253-264
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• 2003

철강산업은 자동차용 강판 공급체인의 총체적 측면에서 볼 때 자동차산업의 핵심 공급자로서 중요한 역할을 수행하고 있다. 1990년대 초반 이후 자동차용 바디 제조공정에 테일러 웰디드 브랭크, 하이드로포밍 등 첨단금속소재 가공기술이 다양한 부위에 널리 적용되고 있다. 한편 자동차업계 및 철강업계는 설비 공급과잉에 따른 치열한 생존경쟁이 전개되는 가운데 이들 업계를 둘러싼 경영환경이 급속히 변화하고 있다. 본 연구에서는 기술혁신 및 경영 환경변화가 급속하게 전개되는 글로벌 마켓에서 자동차 바디용 강판 공급체인 상의 철강업체 역할 변화를 고려하고자 한다. 철강산업은 완성차업체 및 자동차 최종고객을 만족시키기 위한 원가절감 전략을 구현하는 동시에 소재 프로세싱 분야에 대한 기술역량을 축적하여야 한다. 이것이 현재 경쟁업체, 신규진입업체 및 대체 소재산업들과의 경쟁환경에서의 철강업체의 성공전략이다.