http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Duc-Toan Nguyen,김영석,정동원 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
In this study, pre-coated material was applied in roll-bending process to make 90 degree wall angle with various corner radii. Based on the desired corner radius value, a die radius and bending angle should be selected to obtain corrected shape. To predict spring back in roll-bending process, combined kinematic/isotropic hardening law was used and shown more accuracy with other laws when comparing with corresponding experiment data. To decide die radius and bending angle for desired shape, several values of die radius and bending angle of roll bending process were first changed to simulate and investigate corner radius and wall angle of blank after spring-back. A MATLAB tool was then utilized to determine the corner radius and wall angle of blank after spring-back as functions of die radius and bending angle using a surface fitting method. Finally, the die radius and bending angle were obtained by solving intersection curve equations between desired planes of corner radius and 90 degree wall angle with fitted surface.
Nguyen, Duc-Toan,Kim, Young-Suk,Jung, Dong-Won 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.8
In this study, pre-coated material was applied in roll-bending process to make 90 degree wall angle with various corner radii. Based on the desired corner radius value, a die radius and bending angle should be selected to obtain corrected shape. To predict spring back in roll-bending process, combined kinematic/isotropic hardening law was used and shown more accuracy with other laws when comparing with corresponding experiment data. To decide die radius and bending angle for desired shape, several values of die radius and bending angle of roll bending process were first changed to simulate and investigate corner radius and wall angle of blank after spring-back. A MATLAB tool was then utilized to determine the corner radius and wall angle of blank after spring-back as functions of die radius and bending angle using a surface fitting method. Finally, the die radius and bending angle were obtained by solving intersection curve equations between desired planes of corner radius and 90 degree wall angle with fitted surface.
Flow Stress Equations of Ti-6Al-4V Titanium Alloy Sheet at Elevated Temperatures
Duc-Toan Nguyen,김영석,정동원 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
In this study, to achieve constitutive equations of Ti-6Al-4V alloy sheet, uni-axial tensile tests of Ti-6Al-4V alloy sheet with thickness of 1.0mm were performed at elevated temperature of 400oC ~ 700oC. Equations of stress-strain curves are established for Ti-6Al-4V alloy sheet at elevated temperatures describing both work-hardening and softening stage of Ti-6Al-4V alloy sheet. Least square fitting method is used to determine material parameters. The parameters of fitting curves are utilized to determine them as a function of temperature using polynomial models. New mathematical models are used to calculate and predict the stress-strain curves at elevated temperatures. The calculated flow stress curves are in good agreement with experimental data and shown better than that of previous equation.
Improving formability of tube bending for a copper material using finite element simulation
Duc-Toan Nguyen,Dinh-Thanh Nguyen,김영석 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10
Bending tubes are key products in many industries. The geometric parameters of the bending process are considered according to Taguchi’sorthogonal array and then coupled with finite element simulation to predict and improve the formability of the tube bendingprocess for copper JIS25A material. Three parameters, namely, mandrel diameter, distance between mandrel rings, and distance from thetip of the mandrel bar to the center of the base die, are selected to study their effects on the quality of the bending process. The varianceanalysis shows that the effect distribution of each parameter to bending quality is determined, and optimal conditions are adopted to conductexperiments.