Longitudinal inverted compressibility in super-strained metamaterials

TL;DR

This paper develops a statistical physics theory and a predictive model for super-strained metamaterials that exhibit longitudinal contraction under tension, revealing novel inverted phase transition behaviors beyond equilibrium conditions.

Contribution

It introduces a first-principles model for forbidden solid-solid phase transitions in super-strained metamaterials and validates it with molecular dynamics simulations.

Findings

Prediction of longitudinal contraction during tension increase

Validation of the model through simulations

Identification of potential inverted responses in related systems

Abstract

We develop a statistical physics theory for solid-solid phase transitions in which a metamaterial undergoes longitudinal contraction in response to increase in external tension. Such transitions, which are forbidden in thermodynamic equilibrium, have recently been shown to be possible during the decay of metastable, super-strained states. We present a first-principles model to predict these transitions and validate it using molecular dynamics simulations. Aside from its immediate mechanical implications, our theory points to a wealth of analogous inverted responses, such as inverted susceptibility or heat-capacity transitions, allowed when considering realistic scales.