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Delayed yielding of amorphous materials
Amorphous solids include soft materials such as emulsions, foams, colloids, granular matter, and gels, as well as harder metallic and molecular glasses. In contrast to conventional crystalline solids, the internal arrangement of their constituent microstructures (emulsion droplets, foam bubbles, etc.) lacks any intrinsic order. Understanding the rheological (deformation and flow) properties of these materials thus poses a considerable challenge. Typically, they behave elastically at low loads then yield plastically at larger loads. In this talk I shall summarise recent progress in understanding the yielding transition between an initially solid-like state and a finally fluidised one, as a function of time since the application of an imposed strain or load, with a particular focus on the concept that yielding can be very heavily delayed after the inception of shear.