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Using soft excitations to predict and understand plastic flow in disordered solids
Imposing an external driving, amorphous solids can flow via a succession of plastic rearrangement of localized particles. Numerous numerical and experimental studies have shown that loci of plastic instability in glasses are triggered by spatially localized soft spots in direct analogy with dislocations present in crystalline solids, although the population and microscopic structure of the former being significantly different from the latter. The detection and nature of such “amorphous defects” have received a lot of attention, one of the goals being to predict from the microscopic structure itself which regions are likely to undergo a rearrangement upon deformation. In this context, I will discuss novel indicators that are constructed from an analysis of the potential energy landscape and show how one can construct anisotropic descriptors that consider the tensorial nature of the coupling of a soft spot with a particular loading geometry. These methods will be illustrated in the context of strain localization and fracture.