Degenerated Shell Element Analysis of Square Rail Drawing of Sheet Metal

摘要

The prediction of formability in sheet metal forming by numerical simulation allows the manufacturer to reduce the costs of designing tools and to shorten the time-to-market cycle. This paper presents the numerical investigation on the formability of the sheet metal forming by a finite element method. The finite element method code for sheet metal forming simulation was developed based on the static-explicit finite-element method. An elastic-plastic incremental finite-element computer code, based on an updated Lagrangian formulation, was developed to simulate the square rail drawing of sheet metal. In particular, selective reduced integration was adopted to formulate the stiffness matrix. The extended r-minimum technique was used to deal with the elastic-plastic state and contact problems at the tool-metal interface. Experiments and simulations of square rail drawing were performed. The whole deformation history and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite-element method. Results in this study clearly demonstrated that the computer code for simulating the square rail drawing process was efficient. Moreover, the simulated thickness distribution which have two local thinning at the corner of the die shoulder and at the corner of the square hole well agreed with the experimental one, thus demonstrating the validity of the developed code.