Structural relaxation of porous glasses due to internal stresses and deformation under tensile loading at constant pressure

TL;DR

This study uses molecular dynamics simulations to analyze how porous glasses evolve under constant pressure, revealing compaction, energy relaxation, and deformation behaviors during tensile loading.

Contribution

It provides new insights into the structural relaxation and deformation mechanisms of porous glasses under tensile stress at constant pressure.

Findings

Porous glasses become more compact and lower in potential energy over time.

Elastic modulus and density increase with waiting time following a power-law.

Low-density samples deform and fracture under tensile loading, while dense glasses remain homogeneous.

Abstract

The time evolution of the pore size distributions and mechanical properties of amorphous solids at constant pressure is studied using molecular dynamics simulations. The porous glasses were initially prepared at constant volume conditions via a rapid thermal quench from the liquid state to the glassy region and allowing for simultaneous phase separation and material solidification. We found that at constant pressure and low temperature, the porous network becomes more compact and the glassy systems relocate to progressively lower levels of the potential energy. Although the elastic modulus and the average glass density both increase with the waiting time, their dependence is described by the power-law function with the same exponent. Moreover, the results of numerical simulations demonstrated that under tensile loading at constant pressure, low-density porous samples become significantly deformed and break up into separate domains at high strain, while dense glasses form a nearly homogeneous solid material.