The effect of a reversible shear transformation on plastic deformation of an amorphous solid

2016

The influence of periodic shear deformation on nonaffine atomic displacements in an amorphous solid is examined via molecular dynamics simulations. We study the three-dimensional Kob-Andersen binary mixture model at a finite temperature. It is found that when the material is periodically strained, most of the atoms undergo repetitive nonaffine displacements with amplitudes that are broadly distributed. We show that particles with large amplitudes of nonaffine displacements are organized into compact clusters. With increasing strain amplitude, spatial correlations of nonaffine displacements become increasingly long-ranged, although they remain present even in a quiescent system due to thermal fluctuations.

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Nonaffine rearrangements of atoms in deformed and quiescent binary glasses

2016

“…Furthermore, during cyclic shear near the yield strain, a cluster of atoms with large reversible nonaffine displacements induces a long-range, time-dependent elastic field that in turn might trigger secondary structural rearrangements. This situation was considered separately in recent studies [31,32], where it was found that a local reversible shear transformation in a quiescent system induces irreversible cage jumps, and their density is larger in the cases of weaker damping or slower shear transformation.…”

Section: Introductionmentioning

confidence: 99%

Collective nonaffine displacements in amorphous materials during large-amplitude oscillatory shear

2017

Using molecular dynamics simulations, we study the transient response of a binary LennardJones glass subjected to periodic shear deformation. The amorphous solid is modelled as the three-dimensional Kob-Andersen binary mixture at a low temperature. The cyclic loading is applied to slowly annealed, quiescent samples, which induces irreversible particle rearrangements at large strain amplitudes, leading to stress-strain hysteresis and a drift of the potential energy towards higher values. We find that the initial response to cyclic shear near the critical strain amplitude involves disconnected clusters of atoms with large nonaffine displacements. In contrast, the amplitude of shear stress oscillations decreases after a certain number of cycles, which is accompanied by the initiation and subsequent growth of a shear band.

“…Furthermore, a local plastic event in sheared amorphous solids induces long-range deformation that in turn might trigger secondary events and give rise to avalanches [12]. In related studies, it was shown that a local reversible shear transformation in a quiescent system results in cage jumps (discrete events where particles escape from cages of their neighbors) whose density is larger in the cases of weakly damped dynamics or slow shear transformation [13,14].…”

Section: Introductionmentioning

confidence: 99%

Reversible plastic events during oscillatory deformation of amorphous solids

2016

The effect of oscillatory shear strain on nonaffine rearrangements of individual particles in a three-dimensional binary glass is investigated using molecular dynamics simulations. The amorphous material is represented by the Kob-Andersen mixture at the temperature well below the glass transition. We find that during periodic shear deformation of the material, some particles undergo reversible nonaffine displacements with amplitudes that are approximately power-law distributed. Our simulations show that particles with large amplitudes of nonaffine displacement exhibit a collective behavior; namely, they tend to aggregate into relatively compact clusters that become comparable with the system size near the yield strain. Along with reversible displacements there exist a number of irreversible ones. With increasing strain amplitude, the probability of irreversible displacements during one cycle increases, which leads to permanent structural relaxation of the material.