Analysis of Elliptical Cup Drawing Process of SUS304 Stainless Metal
A methodology of formulating an elasto-plastic three-dimensional finite element model, which is based on Prandtl-Reuss flow rule and von Mises yield criterion respectively, associated with an updated Lagrangian formulation. An extended r-min algorithm is proposed to formulate the boundary conditions, such as the yield of element, maximum allowable strain increment, maximum allowable rotation increment, maximum allowable equivalent stress increment, and tolerance for nodes getting out of contact with tool. In order to verify the reliability and accuracy of the FEM code, the fractured thickness of a specimen in the simple tension test is adopted as the fracture criterion of forming limit in simulation. A set of tools was designed to perform the elliptical cup drawing experiment on the hydraulic forming machine. According to the simulation and experimental results, the minimum thickness is concentrated on the contact regions between work-piece and punch major axis, because the camber radius is relatively large along the minor axis, the ones that bear are relatively small to the circular tensile stress, so the thickness does not change much. The limit drawing ratio (LDR) amounts to about 2.136 for penetration in the elliptical cup drawing process of this study. According to the definition of LDR, when the die radius is increased from R3.0mm to R9.0mm, the LDR would increase from 2.11 to 2.157. When the punch radius is increased from r3.0mm to r9.0mm, the LDR would increase from 2.07 to 2.181. This paper has provided a better understanding of the elliptical cup drawing process for improving the manufacturing processes and the design of tools.
M. S. J. Hashmi, B. S. Yilbas and S. Naher
Y. M. Huang and Y. W. Tsai, "Analysis of Elliptical Cup Drawing Process of SUS304 Stainless Metal", Advanced Materials Research, Vols. 83-86, pp. 350-357, 2010