A multiscale framework for the structural response of hybrid CNT/SiC-reinforced aluminium composite beams

A multi-scale finite element (FE) framework was developed to analyse the bending, buckling, and free-vibration behaviours of carbon nanotube (CNT)-reinforced aluminium (Al) nanocomposite beams while explicitly accounting for the interphase between CNTs and the metal matrix. A three-phase representative volume element (RVE) comprising CNTs, Al matrix, and an interphase region was employed to determine the effective elastic modulus and density for CNT volume fractions of 2%, 5%, and 10%. The homogenized properties were then incorporated into macroscale FE models of cantilever beams using 2D (beam, plane-stress) and 3D (shell, brick) elements. The predicted elastic moduli showed excellent agreement with experimental data (deviation < 5%), confirming the accuracy of the homogenization scheme. CNT reinforcement substantially improved structural performance: maximum deflection decreased by ∼21%, critical buckling loads increased by 5%–27%, and the first-mode natural frequency rose by ∼16% with 10% CNT. All FE formulations produced consistent results, with 3D models additionally capturing torsional and out-of-plane effects. Overall, the proposed framework successfully links nanoscale reinforcement to macroscale mechanical behaviour, demonstrating that CNT–Al nanocomposites offer outstanding stiffness, stability, and dynamic performance for lightweight structural and aerospace applications.