Enhanced thermal buckling resistance of folded graphene reinforced nanocomposites with negative thermal expansion: From atomistic study to continuum mechanics modelling

Materials with tunable negative thermal expansion (NTE) are of crucial importance in engineering applications. Currently, the route to achieving large tunability for the coefficient of thermal expansion (CTE) in metal matrix composites (MMCs) is very limited. This paper develops folded graphene (FGr) structures to engineering the CTE of MMCs by embedding the FGr into a copper (Cu) matrix through the molecular dynamics (MD) method. Moreover, the present work investigates the thermal buckling resistance capability of the NTE material composite beam using the classical Euler-Bernoulli beam theory and Ritz method. Atomistic studies based on the MD simulations show that the CTE of FGr/Cu nanocomposite can be effectively tuned by mechanical prestress and temperature, especially within the range from 200 K to 400 K. By using the origami-patterned FGr designed herein, the maximum negative and positive CTEs can reach approximately -95.42 x 10(-6) K-1 and 56.32 x 10(-6) K-1 under the prestress of 1000 MPa at 300 K and 200 K, respectively. More importantly, the quantitative relationship of the temperature- and prestress-dependent material properties of the FGr/Cu composites are built. Based on the built material model, the FGr/Cu composite beam exhibits considerably improved thermal buckling performance than the pristine graphene/Cu beam.

Automated summary

This study developed folded graphene structures to tune the coefficient of thermal expansion of metal matrix composites, and investigated the thermal buckling resistance capability of the composite materials. The atomistic studies showed that the CTE of FGr/Cu nanocomposites can be effectively tuned by mechanical prestress and temperature within a certain range, providing potential for improving thermal performance.