Investigation on the Formability of a Tube in Pulsating Hydroforming

Based on the finite element simulation of tube-hydroforming process with pulsating internal pressure, the influence of the pressure increment Delta p and the time increment Delta t of the pulsating pressure upon the formability of a tube have been investigated by analyzing and comparing the four formability indicators such as thickness distribution, die-filling ability, wall thickness uniformity and potential fracturing. A new indicator f is proposed to estimate the formability of a tube on the basis of the finite element analysis (FEA). The results show that: the indicator f can reasonably reflect the combination formability of a tube in hydroforming including the die-filling ability, the wall-thickness uniformity and the deformation reliability; the Delta p and Delta t values have different influence on the four formability indicators as mentioned above; the smaller the Delta p and Delta t values or the more the internal pressure pulsates during the forming process, the better the combination formability of the tube would be.