ELASTOPLASTIC FINITE-ELEMENT ANALYSIS OF V-SHAPE SHEET BENDING

This paper explores the application of the incremental updated Lagrangian elasto-plastic finite-element method to the V-shape sheet-bending process. In particular, the selective reduced integration is adopted to form the stiffness matrix and the extended r-minimum technique is used to deal with the elastic-plastic state and contact problems between the tool-metal interface. Also, experimental tests were performed to validate the formulation of the theory and the development of the computer code. The predicted value of the punch load in the finite-element model shows good agreement with the results of experiment. In addition, it is shown that the contour of the plot of the strain energy density can be used in the prediction of the fracture position in the sheet. A special feature is that the phenomena of spring-back and spring-forward after unloading can be simulated successfully by the computer program. The whole deformation history of the forming process, the nodal velocity and the distribution of stress and strain are obtained by considering carefully the moving boundary condition in the finite-element method.