http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
축대칭 압출 공정에서 상계법을 이용한 금형 접촉면압의 계산
최영(Young Choi),여홍태(Hongtae Yeo),허관도(Kwando Hur) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.12
In general, the contact pressure to the die cannot be easily determined by using upper bound solution. Recently, the authors have proposed the method determining the contact pressure with the upper bound solution for the forming with the plane stain plastic deformation. In this paper, the method is applied to an axisymmetric forward extrusion process. The contact pressure to the die of the axisymmetric extrusion has been determined with the upper bound solution and compared with the result of rigid plastic FEM. The optimal semi-angles of die have been obtained minimizing the relative contact pressure to die for the extrusion ratio.
강소성 유한요소해석에 의한 비정상상태 금속성형 해석에서 형상 갱신을 위한 혼합법
최영(Young Choi),여홍태(Hongtae Yeo),허관도(Kwando Hur) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.11
The volume of the metal is not changed for the plastic deformation. For metal forming simulation, rigid-plastic FEM codes are widely used. Updating geometry using Euler method in the simulation, the volume loss is occurred. In this paper, hybrid method is introduced to perform a more accurate simulation reducing computation time. In the proposed hybrid method, RK2 method is used for geometry updating at first time step and after the boundary condition of the node is changed. At the others, Adams-Bashforth or theta method is applied to update geometry. The results show that the simulations of upsetting and side-pressing can be performed within 0.02%.
개폐 시 최소 간섭을 갖는 버터플라이 밸브 다시크의 설계
최영(Young Choi),부광석(Kwangsuk Boo),여홍태(Hongtae Yeo),허관도(Kwando Hur),김호관(Hokwan Kim) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.12
In this study, the design and analysis of a butterfly valve disk was performed to minimize the rubbing between the disk and the seat at opening and closing. The butterfly valve has double eccentric structure and the contact surface between the disk and the seat is a conical surface. At the instant of opening and closing the valve by the rotation of disk, the positions of zero contact point are changed. Also, if the cone surface is cut in the perpendicular direction to the rotation axis of the valve, the contour of cutting section is hyperbolic. Therefore minimum distance between the origin of the eccentric axis and the hyperbolic curve goes to the position of zero contact point. In order to consider the interferences between the disk and the seat, the thermal-structure coupled field analysis was performed by ANSYS.