Topological Control on Atomic Networks' Relaxation Under Stress

TL;DR

This study explores how atomic topology influences stress-induced relaxation in calcium-silicate-hydrates, revealing that isostatic networks exhibit minimal relaxation, which could inform the design of non-aging materials.

Contribution

It demonstrates the relationship between atomic topology and relaxation behavior under stress using molecular dynamics and topological constraint theory.

Findings

Isostatic networks show minimal relaxation.

Delayed logarithmic shear deformation observed in C--S--H.

Topological nano-engineering may lead to non-aging materials.

Abstract

Upon loading, atomic networks can feature delayed viscoplastic relaxation. However, the effect of composition and structure on such a relaxation remains poorly understood. Herein, relying on accelerated molecular dynamics simulations and topological constraint theory, we investigate the relationship between atomic topology and stress-induced relaxation, by taking the example of creep deformations in calcium--silicate--hydrates, the binding phase of concrete. Under constant shear stress, C--S--H is found to feature delayed logarithmic shear deformations. We demonstrate that the propensity for relaxation is minimum for isostatic atomic networks, which are characterized by the simultaneous absence of floppy internal modes of relaxation and eigen stress. This suggests that topological nano-engineering could lead to the discovery of non-aging materials.