analysis of axisymmetric and non-axisymmetric stretching of sheet metals by the finite element method

stretching process of sheet metals in both cases of axisymmetric and non-axisymmetric is analyzed. a rigid-plastic, normal anisotrop material is assumed and large strain formulation is applied. triangular elements are used and stiffness equations of elements are obtained from virtual work principle. these nonlinear equations are linearized by newton-raphsons method and are solved by gaussian elimination technique. punch displacement is applied incrementally and deformation of sheet specimen is obtained by calculation of displacement of nodes at each increment. after convergence of calculations at each increment, results which include nodes displacements, strains and stresses at elements, nodal forces and total punch force, etc., are saved and initial guesses are updated. this procedure is continued up to an obtainable or desired punch stroke. results of this analysis are presented and their comparison with other available theoretical and experimental works are very satisfactory.