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[특별세션]DIC 액압벌지실험을 이용한 순 티타늄 판재의 소성유동곡선에 관한 연구
김진재(Jinjae Kim),김영석(Youngsuk Kim),권성진(Seongjin Kwon) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5
In this paper, the plastic flow curve of commercially pure titanium sheet (CP Ti) has been evaluated using Tensile test and Hydraulic bulge test. The plastic flow curve known as hardening curve is a key on factor needed in conducting finite element analysis for the forming process of sheet material. However, several sheet forming processes lead to the large plastic deformation of which the plastic strain is over the maximum uniform elongation of uniaxial tensile test, for instance, clinch forming, hydroforming, stamping and deep drawing. Therefore, we have performed tensile and a hydraulic bulge test for CP Ti sheet. We also have used and evaluated three method that convert from hydraulic bulge flow curve to tensile flow curve. The measured true flow curve from the hydraulic bulge test can be fitted well by the hardening equation known as Kim-Tuan model.
재료변수와 공정변수가 스템핑 성형성에 미치는 영향 연구
김영석,박기철,Kim, Youngsuk,Park, KeeChul 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.7
To investigate the effect of material and precess variables on stamping formability of sheet materials, simulations for the cup drawing and the Yoshida buckling test were carried out using ABAQUS, commercial nonlinear finite element analysis code. The various factor effects on stamping formability of sheet materials were analyzed by the designed process according to Taguch's orthogonal array experiment. Cup drawing simulation showed that local neckling was very sensitive to plastic anisotropy parameter of sheet material and friction coefficient between sheet and tool interface. Simulations for the Yoshida buckling test have clarified that buckling behaviour of sheet material was mostly susceptible to yield stress and sheet thickness mostly. However, plastic anisotropy parameter and strain hardening coefficient affect moderately buckling behaviour of steel sheets after the buckling initiation.
김영석(Youngsuk Kim),김기수(Kisoo Kim),권남철(Namchul Kwon) 한국자동차공학회 1993 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Press formabilities of aluminum sheets for automobile body were investigated. plane strain stretching test (PSST), cupping test and U bending test were performed to assess the press formability of aluminum sheets respectively. The results showed that aluminum sheets are generally inferior to cold-rolled steel sheet of deep drawing quality (CSP3N) in press formability. The limiting punch height (LPH) and limiting plane strain (FLCl) of aluminum sheets are 50%-70% level compared to that of CSP3N. Moreover, the limiting drawing ratios (LDR) of aluminum sheets are ranged between 1.95 and 2.1. The poor press formability of aluminum sheets is responsible for low valuse of total elongation and plastic anisotropy parameter in tensile characteristic. The shape fixability of aluminum sheets evaluated in Ubending test is very poor 엳 새 its low elastic modulus compared to CSP3N. Kew words: press formability, plane strain stretching test,, aluminum sheet, Shape fixability <br/>
김영석(Youngsuk Kim),김재석(Jaesuk Kim),이운성(Woonsung Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study, an information transmission device for an Adaptive Cruise Control System has been designed to provide a driver with the system. The driver car, and other cars. A Simulator experiment has been carried out to investigate the effectiveness of the device by measuring headway-time and standard deviation of lateral position. The study shows that the drivers keep longer distance with preceding cars when the information is provided by the device.