Hydroforming and buckling of an egg-shaped shell based on a petal-shaped preform

This paper describes an experimental and numerical study of the hydroforming and buckling of an egg-shaped shell based on a petal-shaped preform. The preform was welded from 12 meridionally interconnected bent petals with a uniform thickness of 1.38 mm. Before bending, the blanked petals had a maximum width of 69.1 mm and a length of 474.6 mm. Each welding line between adjacent petals corresponded to the meridian of the target egg-shaped shell. The petal-shaped preform was filled with tap water and internally pressurized for hydroforming. The hydroformed egg-shaped shell was immersed in a pressure chamber for hydrostatic testing. After the experiment, the nonlinear finite element method was used to numerically study the hydroforming and buckling of the egg-shaped shell and the effect of internal pressure and weld seams on the buckling. •Egg-shaped shell was fabricated via free hydroforming technique.•Petal-shaped preform had 12 meridionally interconnected bent petals.•Numerical estimations agreed well with experimental observations.•Effects of hydroforming and welding on the buckling were explored.