Abstract
Evidence is presented which indicates that, for stiffened cylinders fabricated by welding, initial deflections exist for the shell between frames. The initial deflections of the shell of a stiffened cylinder were measured and found to be approximated closely by a second-degree curve. Using the mathematical expression for the initial deflection curve, a theoretical analysis was made for a cylinder subjected to external hydrostatic pressure, resulting in expressions for the additional deflections and stresses caused by the initial deflection of the shell. Since the initial deflections of the shell for internally and externally framed cylinders were found to be of opposite sign, the theory is offered as a possible explanation of the observed differences in behavior between internally and externally framed cylinders.
