LMA - Laboratoire de Mécanique et d’Acoustique

J. Marthelot - Morphing soft structures with instabilities

Amphithéâtre François Canac, LMA

Le 7 janvier 2020 de 11h00 à 12h00

Joel Marthelot (IUSTI)

Fracture and buckling of slender structures are typically regarded as a first step towards failure. Instead, we envision mechanical and interfacial instabilities in structures as opportunities for scalable, reversible, and robust mechanisms that are first to be predictively understood, and then harvested for function. I will first show how delamination and fracture cooperate in thin films leading to the propagation of robust fracture patterns that offer opportunities to use cracks as a tool to design surfaces at small scales. I will then focus on thin elastic shells, where elastic buckling is highly sensitive to imperfections and often catastrophic. At loads below the buckling load, buckling can be triggered by extraneous disturbances. I will show that by probing a shell loaded below its buckling pressure, we can measure its energy barrier and ascertain its buckling load. Periodic dimpled patterns are observed when the shell is constrained from within by a rigid mandrel. We find that the geometry of the system is central in setting the surface morphology. This prominence of geometry suggests a scalable, and tunable mechanism for reversible shape-morphing of shells.

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