Numerical and experimental confirmation of the calibration stage's effect in multi-operation sheet hydroforming using poor-formability materials

Based on the proposed multi-operation hydroforming with the non-uniform blank holding pressure unit, using the poor formability materials including aluminum alloy and high-strength steel alloy, the effects of key process parameters including the shape of pre-forming punch, pre-forming depth, blank shape and cavity pressure, punch movement on the finally formed parts were discussed. Typical failure types including fracture and wrinkling were studied. By using the numerical simulation method, and process parameters were optimized. It was proved that the results from the experiment and the simulation were in a reasonable agreement.