Dieless bulging and nonlinear buckling of longan-shaped pressure hull

In this study, the dieless bulging and nonlinear buckling behaviours of a stainless longan-shaped pressure hull were investigated. According to the Cassini oval equation, the longan shape has a shape index of 0.1. The lengths of the major and minor axes of the designed longan-shaped pressure hull were approximately 400 and 396 mm, respectively. The wall thickness of this pressure hull was 1 mm. The Huber–von Mises stress and first yielding load of the designed longan-shaped shell and its inscribed polyhedral preform were investigated analytically and experimentally. Moreover, the dieless bulging of the designed longan-shaped pressure hull was investigated numerically and experimentally by using the nonlinear finite element method and a hydrostatic test, respectively. The analytical, experimental, and numerical results exhibited good agreement with each other.