Collapse of helical cylindrical shells subjected to external hydrostatic pressure

The present study investigated the collapse performance of helical cylindrical shells subjected to external pressure. Helical cylindrical shells, cylindrical shells, and helically stiffened cylindrical shells were designed, fabricated, geometrically measured, and hydrostatically tested. Linear eigenvalue and nonlinear Riks analyses were performed to evaluate the collapse properties of the fabricated shells. The experimental and numerical results of this study were in agreement. In addition, the existing shapes of shells were used to make a comparison with the helical cylindrical shell. The effects of the spiral rib and wall thickness on the collapse properties of helical cylindrical shells were investigated numerically. The results indicated that a helical cylindrical shell with a spiral cambered surface and spiral rib has considerably higher loading capacity than an ordinary cylindrical shell does. A spiral rib can improve the collapse behaviour of helical cylindrical shells and change their collapse modes.