Theoretical and experimental study of the free hydroforming of egg-shaped shell
Jian Zhang, Mingqiang Dai, Fang Wang, Wenxian Tang, Xilu Zhao, Yongmei Zhu
Abstract
This study investigated the free hydroforming of a stainless-steel egg-shaped shell. An egg-shaped shell is a promising geometry for deep pressure hulls. The length and width of the egg-shaped shell were 512.40 and 356.25 mm, respectively. The wall thickness of the egg-shaped shell were 0.844 mm. The equivalent stress, yielding load, internal capacity, and surface area of the egg-shaped shell and its inscribed segmented preform were investigated analytically and experimentally. The hydroforming performance of the egg-shaped shell was analysed using the nonlinear finite element method, and the results were validated by experimental model tests. The results indicated that free hydroforming can be an effective technique for fabricating egg-shaped pressure hulls and can yield highly symmetric shells of revolution regardless of the large geometric deviation of the segmented preform.