Internal Hydroforming of Large Stainless-Steel Eggshells from Stepped Preforms

The internal hydroforming of large stainless-steel eggshells from a stepped preform is investigated in this paper. nominal major and minor axes the eggshell were 1537 1070 mm, respectively. was fabricated thin-walled (1.9 mm thick) sheets comprised twelve conical segments inscribed inside target eggshell. then hydroformed, its wall thickness shape measured. yield load distribution material hardening process analytically. Nonlinear finite-element analyses employed to further investigate behaviors effect weld lines on hydroforming. experimental, numerical, analytical results consistent. confirm that, during process, considerable springback occurs for eggshells, which greatly affects forming precision. However, can be reduced by accounting strengthening lines.