Annealing effects of multidirectional oscillatory shear in model glass formers

Abstract

We study the effects of cyclic, athermal quasi-static shear on a model glass-forming system in three dimensions. We utilize the three available orthogonal shear planes, namely XY, Y Z and XZ to better explore the energy landscape. Using measurements of the stroboscopic (γ = 0) energy, we study the effects of using an orthogonal shear direction to perturb unidirectional steady-states. We find that that each sequence of the unidirectional protocol leads to compaction with the universal, ∆E ∼ N −1 behavior as a function of the number of cycles, N . Additionally we find that cyclic shear utilizing multiple shear planes presents hierarchical compaction, producing progressively lower steady state energies compared to a protocol involving unidirectional cyclic shear alone. Furthermore, with the periodicity of the stroboscopic energy as reference, we show that it is possible to achieve steady state limit-cycles of tunable periodicities using different combinations of the three orthogonal strain directions. We find that such protocols exhibit better annealing as compared to protocols with steady states created using unidirectional shear. Importantly, we find a non-trivial trend in the annealing energy and the period of the steady-state limit-cycle, with an aperiodic protocol appearing to produce the most well annealed states. Finally, we compare the phase diagram of the average steady state energy E S.S. , as a function of the shearing amplitude γmax, using unidirectional and multidirectional protocols, and find that the universal features are preserved.

Relaxation dynamics in amorphous alloys under asymmetric cyclic shear deformation

“…It was further shown that under smallamplitude cyclic loading, rapidly quenched glasses undergo structural relaxation, termed as 'mechanical annealing', and gradually evolve towards low-energy steady states [28,37,40,41,45]. In some cases, mechanically induced annealing can be accelerated when the shear orientation is periodically alternated in two or three spatial dimensions [41,50] or if the strain amplitude of cyclic loading is occasionally increased above a critical value [51]. More recently, it was found that the yielding behavior in binary glasses under asymmetric cyclic shear deformation is markedly different from the case of symmetric loading, https://doi.org/ 2) for the strain amplitude 𝛾 0 = 0.10.…”