Non-linear collapse behavior of externally pressurized resin toroidal and cylindrical shells: numerical and experimental studies

The purpose of this paper is to elaborate the non-linear collapse of externally pressurized resin toroidal and cylindrical shells, along with a comparison between a toroid and cylinder. For this purpose, the collapse characteristics, critical loads, and imperfection sensitivities of volume equivalent shells were numerically evaluated for the first eigenmode imperfection. Furthermore, three nominally identical toroidal shells and three equivalent cylindrical shells were rapidly prototyped, optically scanned, ultrasonically measured, hydrostatically tested, and numerically examined. The numerical and experimental data were consistent with each other. The average pressure supporting capacity of the toroidal shell was approximately 29% higher than that of its volume equivalent cylindrical shell, thus demonstrating a superior pressure supporting capacity of the toroid. The knock down factors of the cylindrical shell were considerably lower than those of the toroidal shell, thus indicating that the toroidal shell is considerably less sensitive to initial geometrical imperfection than the cylindrical shell.