Viscoelasticity has been described since the time of Maxwell as an interpolation of purely viscous and purely elastic response, but its microscopic atomic-level mechanism in solids has remained elusive. We studied three model disordered solids: a random lattice, the bond-depleted fcc lattice, and the fcc lattice with vacancies. Within the harmonic approximation for central-force lattices, we applied sum rules for viscoelastic response derived on the basis of nonaffine atomic motions. The latter motions are a direct result of local structural disorder, and in particular, of the lack of inversion symmetry in disordered lattices. By defining a suitable quantitative and general atomic-level measure of nonaffinity and inversion symmetry, we show that the viscoelastic responses of all three systems collapse onto a master curve upon normalizing by the overall strength of inversion-symmetry breaking in each system. Close to the isostatic point for central-force lattices, power-law creep G(t)∼t^-1/2 emerges as a consequence of the interplay between soft vibrational modes and nonaffine dynamics, and various analytical scalings, supported by numerical calculations, are predicted by the theory.
Atomic-scale origin of dynamic viscoelastic response and creep in disordered solids / R. Milkus, A. Zaccone. - In: PHYSICAL REVIEW. E. - ISSN 2470-0045. - 95:2(2017 Feb 01).
|Titolo:||Atomic-scale origin of dynamic viscoelastic response and creep in disordered solids|
ZACCONE, ALESSIO (Ultimo) (Corresponding)
|Settore Scientifico Disciplinare:||Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici|
Settore FIS/03 - Fisica della Materia
|Data di pubblicazione:||1-feb-2017|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1103/PhysRevE.95.023001|
|Appare nelle tipologie:||01 - Articolo su periodico|