The Most Effective Loading Path of Free Bulge Forming of Thin Wall Tubes

The properties of strain paths,localized instability and buckling instability in the process of free bulge forming of tubes were analyzed. The most effective loading path,in which the axial force and the internal pressure were controlled in order to achieve a maximum radial expansion of the tubes,was established.Numerical calculation by finite element methods and experiment were carried out.Encouraging agreement was obtained between the theoretical and experimental results.