Forming limit analysis of hemispherical-punch stretch forming

This paper combines elastic-plastic membrane finite elements and forming li mit theory to determine the limiting dome height of axisymmetric stretch fo rming. The elastic-plastic finite element approach is based on the flow rul e associated with Hill's quadratic yield criterion for anisotropic material . The total Lagrangian formulation and virtual work theory are used to deri ve the stiffness equations and the relationship between displacement and st rain. Using FE-calculation results and forming limit curves proposed by Sto ren and Rice, the limiting dome height and the rupture location were predic ted for various materials. The calculated results are compared with availab le experimental data and existing numerical solutions. Furthermore, the inf luence of material properties (i.e., the strain-hardening exponent and anis otropy) and friction condition on the limiting dome height are presented. ( C) 2001 Published by Elsevier Science B.V.