Puckering instability phenomena in the hemispherical cup test

Abstract

investigated here is the plastic bifurcation of an initially flat circular plate held frictionlessly between a blankholder and a die and deformed by a spherically shaped punch.In view of the large deviations of the prebifurcation solution from proportional loading, a recently developed phenomenological corner theory has been employed and an appropriate bifurcation criterion has been developed. The effects of geometry and material properties on the onset of the (nonaxisymmetric) plastic instability have been investigated using a numerical solution of the resulting equations based on the finite element method.