• Transactions of Materials Processing
• /
• v.13 no.5
• /
• pp.461-465
• /
• 2004

Based on the experimental observation, the mathematical friction model, which is an essential information for analyzing the forming process of sheet metal, is developed considering lubricant viscosity, surface roughness and hardness, punch comer radius, and punch speed. By comparing the punch load found by FEM with a proposed friction model with experimental measurement when the coated and uncoated steel sheets are formed in 2-D geometry in dry and lubricant conditions, the validity and accuracy of the developed friction model are demonstrated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1994.06a
• /
• pp.147-162
• /
• 1994

Generally, the forming process of sheet metal is very complex and difficult process because of many variables such as tool geometry, material properties and lubrication. In this view point, the numerical analysis of sheet metal forming process is very difficult. High speed computer is used to model complex sheet metal forming process on a reasonable time scale. The design and development of sheet metal parts in the automotive industry and the need for improved sheet forming process and reduced part development cost have led to the use of computer simulation in tool/die design of sheet metal pressing. HMC(Hyundai Mator Company) has invested to develop programs for analysis of sheet metal forming process with connection of Universities. As a result, several programs were developed. Recently, the commercial software, PAM-STAMP of ESI was installed and is being tried to application of it to the real automotive panels. This article reviews the ongoing activities on development and application of analytical modeling of sheet metal forming at HMC.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.2
• /
• pp.228-233
• /
• 2002

TWB(Tailor Welded Blanks) is one of the recent techniques to reduce the weight and cost of the body members. To apply the TWB technique, we must decide the position of the welding line and the thickness of the welded blanks. Although many researchers have tried to check the formability of welded blanks, there are not so many researches from the structural point of view. In this paper, the TWB technique is applied to combine the door inner panel and the hinge face panel into one piece. The finite element structural analysis of the door assembly leads to the final design of the tailor welded door inner panel, which shows the mass reduction of 1.08kg without the sacrifice of the structural stiffness. The structural stiffness analysis includes the frame stiffness analysis, the belt line stiffness analysis, the door sagging analysis and the vibration analysis.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.2 s.32
• /
• pp.11-17
• /
• 1999

The objective of this paper is to introduce very fast but still stable solution using finite element procedures, and it has been used in an iterative mode for product design applications. A lot of numerical techniques have been developed to deal with the material, geometric and boundary condition non-linearities occurred in the stamping process. One of them, the One-Step FEM is very efficient and useful tool for a design and trouble-shooting in various stamping processes. In this method, the mathod, the material is assumed to deform directly from the initial flat blank to the final configuration without any intermediate steps. The formulation is based on the deformation theory of plasticity and the upper bound theorem. As a result of the calculations, the initial blank shape is obtained, together with the material flow, strains and thickness distribution in the part.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.4
• /
• pp.810-817
• /
• 1990

본 연구에서는 국부질점 좌표계(natural convected coordinate system)를 이 용하여 변형을 묘사하는 대변형을 고려한 탄소성 증분수식을 유도하고 또 이에 해당하 는 유한 요소 방정식을 구하였다. 국부 질점 좌표계를 사용함으로써 변형도 성분이 나 구성 방정식의 성분들에 대한 좌표 변환 과정을 생략하도록 한다. 재료는 수직 이방성으로 가정하였다. 이 수식화의 타당성을 검증하기 위하여 원형 격막의 정수압 벌징을 해석하고 해석 결과는 실험 결과와 이미 발표된 실험 및 해석 결과와 비교하여 타당성을 검증하였다.

• Proceedings of the KAIS Fall Conference
• /
• 2004.11a
• /
• pp.87-89
• /
• 2004

정밀화와 더불어 고품질화 되고 있는 사출성형 산업에서 CAE기술(Computer Aided Engineering)은 성형 시행오차를 줄여 원가를 절감하고, 생산성을 향상시킬 수 있는 최적의 대안이라 할 수 있다. 본 연구는 이러한 CAE 기술을 활용하여 현장에서 사출성형하기 힘든, 두께 0.3mm인 소형 RC비행기 Battery Case제품을 대상으로 유동해석을 통해 최적 Gate와 유동기구의 설계 조건을 도출하고 구현하고자 하였다.

• 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 the Korean Society of Automotive Engineers
• /
• v.3 no.3
• /
• pp.19-28
• /
• 1995

The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solutions since it improves the convergency problem, memory size and computational time especially for the case of complicated geometry and large element number. The explicit schemes in general use are based on the elastic-plastic modelling of material requiring large computation time. In the present work, rigid-plastic explicit finite element method is introduced for analysis of sheet metal forming processes in which plane strain normal anisotropy condition can be assumed by dividing the whole piece into sections. The explicit scheme is in good agreement with the implicit scheme for numerical analysis and experimental results of auto-body panels. The proposed rigid-plastic explicit finite element method can be used as robust and efficient computational method for prediction of defects and forming severity.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.11-12
• /
• 2007

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.12
• /
• pp.2055-2067
• /
• 1997

Values of process parameters in sheet metal forming can be estimated by various one-step inverse methods. One-step inverse methods based on deformation theory, however, cause some amount of error. The amount of error is generally increased as the deformation path becomes more complex. As a remedy, a new three dimensional multi-step inverse method is introduced for optimum design of blank shapes and strain distributions from desired final shapes. The approach extends a one-step inverse method to a multi-step inverse method in order to reduce the amount of error. The algorithm developed is applied to square cup drawing to confirm its validity by demonstrating reasonably accurate numerical results. Rapid calculation with this algorithm enables easy determination of an initial blank of sheet metal forming.