Finite element analysis of dual hydroforming processes

The tube hydroforming process has gained increasing attention in recent years. With the hydroforming process, manufacturers can realize substantial cost savings as it provides reduced part count, increased part strength and stiffness, and reduced weight. Coordination of the pressurization and feeding curves is critical to generate successful parts without fracture or wrinkling failure. Herein a new process parameter, counter pressure, is introduced to achieve favorable tri-axial stress state during deformation process. This paper will establish the merits of applying external counter pressure in tube hydroforming. It is observed that the counter pressure will provide back support to the tube material. Excessive thinning and premature wrinkling could be prevented. Thus, larger tube expansion could be achieved. The process will be referred as dual hydroforming.