Nondestructive Prediction of the Buckling Load of Imperfect Shells

From soda cans to space rockets, thin-walled cylindrical shells are abundant, offering exceptional load carrying capacity at relatively low weight. However, the actual load at which any shell buckles and collapses is very sensitive to imperceptible defects and can not be predicted, which challenges the reliable design of such structures. Consequently, probabilistic descriptions in terms of empirical design rules are used and reliable design requires to be very conservative. We introduce a nonlinear description where finite-amplitude perturbations trigger buckling. Drawing from the analogy between imperfect shells which buckle and imperfect pipe flow which becomes turbulent, we experimentally show that lateral probing of cylindrical shells reveals their strength non-destructively. A new ridge-tracking method is applied to commercial cylinders with a hole showing that when the location where buckling is nucleated is known we can accurately predict the buckling load of each individual shell, within $\pm 5\%$. Our study provides a new promising framework to understand shell buckling, and more generally, imperfection-sensitive instabilities.