Numerical/experimental investigations for enhancing the sheet hydroforming process

In this work the authors present some results of their research activity aimed to enhance the sheet hydroforming process. The main focus is the adoption of a movable inferior plate through which the control of the blank forming is realised. Tests on hemitoroidal parts using an innovative equipment with a movable die were carried on at the Institute of Metal Research (Chinese Academy of Sciences) in cooperation with the Aalborg University, putting in evidence main defects and fracture causes. Finite element simulations of the modified hydroforming process using a movable inferior plate were performed at the Centre of Excellence for Mechanical Computation (Polytechnic of Bari), with the aim of evaluating critical strain values and their location, strain paths, load curves and stress maps were analysed. Specimens with proper geometrical shape were designed to avoid possible ruptures and to reduce material thinning in the critical regions.