"Shell Buckling—the old and the new" John W. Hutchinson (Harvard University)

Keynote presentation by Prof. John Hutchinson at NEW.Mech (New England Workshop on the Mechanics of Materials and Structures) held at MIT on October 14, 2017. -- "Shell Buckling—the old and the new" John W. Hutchinson Harvard University Abstract: The elastic buckling of shell structures such as spherical shells subject to external pressure and cylindrical shells loaded in axial compression is highly sensitive to imperfections and often catastrophic. The buckling load of such structures is strongly dependent on the level and shape of the geometric imperfections. This is an old and enduring story. At loads below the buckling load, buckling can be triggered in a shell structure by extraneous loads or disturbances. The robustness, or precariousness, of a loaded shell to such disturbances depends on the magnitude of the buckling energy barrier: the difference between the energies of the shell system in the buckled and unbuckled states. Energy barriers are not new in thermodynamical systems where thermal fluctuations can drive a system from one state to another, but the role of the energy barrier in shell buckling has only recently been considered. Recent theoretical and experimental work illustrating the roles of both imperfections and energy barriers in the buckling of spherical shells under external pressure will be discussed. The technique of probing a shell loaded below its buckling pressure to measure its energy barrier and to ascertain its buckling pressure will also be discussed.