Numerical Investigations on the Effect of Pulsating Pressure on Improvement of Formability in Hydroforming of Bent Tube by FEM

In this paper, hydroforming process of bent tubes in T-shaped die is studied for pulsating and linear pressure paths by the finite element method. Forming Limit Diagrams (FLDs) and thickness distribution curves are used to investigate the effect of pulsating pressure on hydroforming process. In addition, the obtained numerical results are compared with experimental results of hydroforming of straight tubes with T-shape protrusions. Itis shown that for tubes with similar bend radius and diameter of bent tube, the formability increases by linear pressure which means pulsating pressure is not so effective. But in the bent tubes whith bend radius larger than tube diameter, pulsating pressure improves formability in hydroforming process. Also, it is found that in hydroforming the pulsating pressure can not increase formability in any bent tube case. In some cases the linear pressure path is more effective for formability.