Buckling of Hydroformed Toroidal Pressure Hulls with Octagonal Cross-Sections

This paper is devoted to the hydroforming performances of toroidal pressure hulls with octagonal cross-sections, together with the buckling performances of hydroformed hulls. The octagonal cross-sections of toroidal preforms are inscribed from the circular cross-sections of perfect toroidal shells with a 150 mm major radius, a 75 mm section radius, and a 1.058 mm wall thickness. The nonlinear finite-element method was employed to study the hydroforming and buckling performances under various hydroforming pressures. To verify the numerical findings, three nominally identical toroidal pressure hulls with discrete octagonal cross-sections were tentatively manufactured, internally hydroformed, and externally collapsed. The numerical and experimental data exhibited satisfactory agreement. It is indicated that the hydroforming technique could greatly enhance the loading capacity of toroidal pressure hulls