Deformation insensitive thermal conductance of the designed Si metamaterial

TL;DR

This study demonstrates that a nano-designed silicon metamaterial with curved nanobeams maintains stable thermal conductance even under large deformation, due to its quasi-zero stiffness and minimal stress changes.

Contribution

It introduces a nano-designed Si metamaterial with curved nanobeams that preserves thermal conductance under large deformation, a novel feature for flexible thermal management materials.

Findings

Thermal conductance remains insensitive under ~-41% strain.

Average stress in nanobeams is ultra-small (<151 MPa) during deformation.

Phonon density of states shows little change under large strain.

Abstract

The thermal management have been widely focused due to broad applications. Generally, the deformation can largely tune the thermal transport. The main challenge of flexible electronics/ materials is to maintain thermal conductance under large deformation. This work investigates the thermal conductance of a nano-designed Si metamaterial constructed with curved nanobeams by molecular dynamics simulation. Interestingly, it shows that the thermal conductance of the nano-designed Si metamaterial is insensitive under a large deformation (strain~-41%). The new feature comes from the designed curved nanobeams which makes a quasi-zero stiffness. Further calculations show that, when under a large deformation, the average stress in nanobeam is ultra-small (<151 MPa) and its phonon density of states are little changed. This work provides valuable insights on multifunction, such as both stable thermal and mechanical properties, of nano-designed metamaterials.