PREDICTION OF THE LIMITING SHAPE AND DIE-HEIGHT IN THE HYDRAULIC BULGE-FORMING OF A CIRCULAR CUP

The hydraulic bulge forming of a circular sheet metal into a cup shape is examined with different blank radius and thickness of the sheet, a nd different heights of the cup. A finite-element numerical algorithm based on the Green-Naghdi stress-rate formulation for an isotropic-har dening material with elasto-plastic behaviour is used to predict the s hape of the cup, the plastic strain distribution and the limiting heig ht of the cup that can be formed successfully. The results of the nume rical simulation are found to give a good prediction of the forming be haviour of metal sheets in hydraulic bulge-forming.