• 한국자동차공학회논문집
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• 제11권6호
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• pp.205-212
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• 2003

This paper may provide a basic design data for the safer car seat mechanism and the quality of the material used by finding out the passenger's dynamic behavior when protected by seat belt during collision. A computer simulation with finite element method is used to accomplish this objective. At first, a detailed geometric model of the seat is constructed using CAD program. The formation of a finite element from a geometric data of the seat is carried out using Hyper-Mesh that is the commercial software for mesh generation and post processing. In addition to seat modeling, the finite element model of seat belt and dummy is formed using the same software. Rear impact analysis is accomplished using Pam-Crash with crash pulse. The part of the recliner and right frame is under big stress in rear crash analysis because the acceleration force is exerted on the back of the seat by dummy. The stress condition of the part of the bracket is checked as well because it is considered as an important variable on the seat design. Front impact model which including dummy and seal belt is analyzed. A Part of anchor buckle of seat frame has high stress distribution because of retraction force due to forward motion of dummy at the moment of collision. On the basis of the analysis result, remodeling and reanalysis works had been repeatedly done until a satisfactory result is obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1980-1983
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• 2005

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excellent price and strength. The sheet metal process with above characteristic is common used in industrial field, but in order to analysis irregular field problems the reliable and economical analysis method is demanded. Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. Among Finite element method, The static-implicit finite element method is applied effectively to analyze real-size auto-body panel stamping processes, which include the forming stage. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planing alloy to reduce law price as well as high precision from Design Optimization of ide. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• 한국정밀공학회지
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• 제23권3호
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• pp.118-124
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• 2006

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excel lent price and strength. The sheet metal process with above characteristic is common used in industrial field, but in order to analysis irregular field problems the reliable and economical analysis method is demanded. Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behavior. Among Finite element method, the static-implicit finite element method is applied effectively to analyze real-size auto-body panel stamping processes, which include the forming stage. In this paper, it was focused on the drawing ability factors on auto-body panel stamping by AUTOFORM with using tool planning alloy to reduce law price as well as high precision front Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• 소성∙가공
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• 제19권8호
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• pp.486-493
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• 2010

A shape error of the sheet metal product made by a flexible stretch forming process is occurred by a various forming parameters. A die used in the flexible stretch forming is composed of a punch array to obtain the various objective surfaces using only one die. But gaps between the punches induce the shape error and the defect such as a scratch. Forming parameters of the punch size and the elastic pad to prevent the surface defect must be considered in the flexible die design process. In this study, tendency analysis of shape error according to the forming parameters in the flexible stretch process is conducted using a finite element method. Three forming parameters, which are the punch size, the objective curvature radius and the elastic pad thickness, are considered. Finite element modeling using the punch height calculation algorithm and the evaluation method of the shape error, which is a representative value for the formability of formed surface, are proposed. Consequently, the shape error is in proportion to the punch size and is out of proportion to the objective curvature radius and the elastic pad thickness.

• 한국분말재료학회지
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• 제16권2호
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• pp.85-90
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• 2009

Magnesium and its alloys are attractive as light weight structural/functional materials for high performance application in automobile and electronics industries due to their superior physical properties. In order to obtain high quality products manufactured by the magnesium powders, it is important to control and understand the densification behavior of the powders. The effect of the sheath surrounding the magnesium powders on the plastic deformation and densification behavior during equal channel angular pressing was investigated in the study by experimental and the finite element methods. A modified version of Lee-Kim's plastic yield criterion, notably known as the critical relative density model, was applied to simulate the densification behavior of magnesium powders. In addition, a new approach that extracts the mechanical characteristics of both the powder and the matrix was developed. The model was implemented into the finite element method, with which powder compaction under equal channel angular pressing was simulated.

• 소성∙가공
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• 제29권2호
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• pp.89-96
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• 2020

The finite element method has been widely applied in the sheet metal forming process. However, the finite element method is computationally expensive and time consuming. In order to tackle this problem, surrogate modeling methods have been proposed. An artificial neural network (ANN) is one such surrogate model and has been well studied over the past decades. However, when it comes to ANN with two or more layers, so called deep neural networks (DNN), there is distinct a lack of research. We chose to use DNNs our surrogate model to predict the behavior of sheet metal in the deep drawing process. Thickness variation is selected as an output of the DNN in order to evaluate workpiece feasibility. Input variables of the DNN are radius of die, die corner and blank holder force. Finite element analysis was conducted to obtain data for surrogate model construction and testing. Sampling points were determined by full factorial, latin hyper cube and monte carlo methods. We investigated the performance of the DNN according to its structure, number of nodes and number of layers, then it was compared with a radial basis function surrogate model using various sampling methods and numbers. The results show that our DNN could be used as an efficient surrogate model for the deep drawing process.

• Journal of Welding and Joining
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• 제10권4호
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• pp.222-229
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• 1992

A prediction of penetration and heat affected zone by using Finite Element Method in CO$_{2}$ Arc Welding has been discussed this paper. The temperature distribution of a base metal produced by the CO$_{2}$ arc welding processing is analyzed by using a three dimensional finite element model. The common finite element program ANSYS 4.4A was employed to obtain the numerical results. Temperature dependent material properties, effect of latent heat, and the convective boundary conditions are included in the model. Numerically predicted sizes of the penetration and the heat affected zone are compared with the experimentally observed values. As a result, there was a slight difference between numerical analysis values and experimentally observed values. For in the case of heat affected zone, it was not considered a precise forced convective coefficient value, and in the case of penetration, it was not, considered a arc force.

• 소성∙가공
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• 제22권3호
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• pp.123-132
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• 2013

Hot stamping, which is the hot pressing of special steel sheet using a cold die, can combine ease of shaping with high strength mechanical properties due to the hardening effect of rapid quenching. In this paper, a thermo-mechanical analysis of hot stamping using the finite element method in conjunction with phase transformations was performed in order to investigate the plastic deformation behavior, temperature history, and mechanical properties of the stamped car part. We also conducted a fully coupled thermo-mechanical analysis during the stamping and rapid quenching process to obtain the mechanical properties with the consideration of the effects of plastic deformation and phase transformation on the temperature histories at each point in the part. The finite element analysis could provide key information concerning the temperature histories and the sheet mechanical properties when the phase transformation is properly considered. Such an analysis can also be used to determine the effect of cyclic cooling on the tooling.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 제5회 박판성형 SYMPOSIUM
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• pp.81-85
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• 2006

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excellent price and strength. The sheet metal process with above characteristic is common used in industrial field, but in order to analysis irregular field problems the reliable and economical analysis method is demanded. Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. Among Finite element method, The static-implicit finite element method is applied effectively to analyze real-size auto-body panel stamping processes, which include the forming stage. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planing alloy to reduce law price as well as high precision from Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• 소성∙가공
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• 제25권2호
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• pp.109-115
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• 2016

In the current study, automatic tool compensation is accomplished by using a finite element stamping analysis for a center roof rail made of UHSS in order to satisfy the specifications for shape accuracy. The initial blank shape is calculated from a finite element inverse analysis and potential forming defects such as tearing and wrinkling are determined by the finite element stamping analysis based on the initial tool shape. The blank shape is optimized to meet the shape requirements of the final product with the stamping analysis, and die compensation is determined with the information about springback. The specifications for shape accuracy were successfully achieved by the proposed die compensation scheme using the finite element stamping analysis. The current study demonstrates that the compensation tendency is similar when the proposed scheme is used or when the compensation is performed by trial and error in the press-shop. This similarity verifies that the automatic compensation scheme can be used effectively in the first stage of tool design especially for components made from UHSS.