Abstract:
The plastic deformation of amorphous solids is primarily driven by the localized re
arrangement or shear transformation of individual particles, which interact with one
another through long-range elastic strain fields. Understanding the spatial and tempo
ral organization of these rearrangements is essential for comprehending the transition
from elastic to plastic deformation. While we have made significant progress in under
standing this phenomenon at low temperatures and under quasi-static deformation
conditions, our comprehension remains limited when it comes to finite deformation
rates and temperatures.
In the following work, we present evidence that interactions between these rear
rangements give rise to consistent patterns of strain distribution in amorphous solids
subjected to shear stress. Through a combination of experiments and simulations,
we have uncovered a specific quadrupolar symmetry in the strain correlations. This
symmetry resembles the strain field produced by an Eshelby inclusion, a concept
from materials science. However, unlike the Eshelby field, these correlations exhibit
a decay pattern characterized by 1/rα, where the exponent α gradually shifts from 3
to 1 as the system progresses from the linear elastic regime to a state of steady-state
plastic flow.
We have further explained these findings by modeling the particles undergoing
shear transformations or rearrangements as if they were Eshelby inclusions. Initially,
at small strains, the plastic rearrangements appear isolated from each other. How
ever, as the applied strain increases, these rearrangements start to cluster together,
and their average size expands. Ultimately, this clustering phenomenon leads to the
system yielding and entering a state of plastic flow.
Our study underscores the importance of density correlations among these plastic
rearrangements and demonstrates how universal patterns of strain distribution emerge
at different stages of the elasto-plastic deformation process.
