Ideal sheet forming with frictional constraints

The ideal forming theory, previously developed as a direct design method to guide iterative design practices based on analytic methods, does not properly account for frictional effects prevalent in real forming. A method for introducing the effects of the Coulomb friction in the ideal sheet forming theory was developed in this work by modifying the extremum work criterion. For numerical implementation, a rigid-plastic finite element method was used based on triangular membrane elements. Computational results were compared with experiments given in NUMISHEET'93 using a planar anisotropic strain rate potential proposed by Barlat et al. and the Coulomb friction model.