Hydroforming and buckling of toroids with polyhedral sections

ABSTRACT

The hydroforming and buckling of toroids with polyhedral sections were examined. The cross section of a polyhedral preform had the form of an irregular octagon with a uniform thickness of 1.1 mm. This octagon was inscribed on the circular section of a target toroid with a rotation radius of 150 mm and a cross-sectional radius of 75 mm. Two nominally identical preforms were fabricated, internally hydroformed, and externally collapsed. The internally and externally applied pressures were recorded, and the geometric shapes and thicknesses were measured before and after the hydroforming process. The nonlinear finite-element method was used to investigate the hydroforming and buckling properties. The experimental results and numerical estimations were compared, and the results indicate that the hydroformed toroid can be employed in underwater vehicles. Jordan’s equation can provide a conservative prediction of the ultimate allowable outer pressure of hydroformed toroids when the hydroforming pressure exceeds a certain threshold.

KEYWORDS:

• Toroid
• polyhedral preform
• hydroforming
• buckling

Acknowledgments

The authors would like to express their gratitude for the support of Fishery Engineering and Equipment Innovation Team of Shanghai High-level Local University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 52071160]; National Natural Science Foundation of China: [Grant Number 52071203]; Excellent Youth Foundation of the Jiangsu Scientific Committee: [Grant Number BK20190103]; Six Talent Climax Foundation of Jiangsu: [Grant Number KTHY-068].