A multi-scale computational framework for the hygro-thermo-mechanical analysis of laminated composite structures with carbon nanotube inclusions

In this work, a multi-scale framework is presented for the estimation of the hygro-thermo-mechanical elastic performance of laminated composite structures with single-walled carbon nanotube (SWCNT) inclusions. The Halpin-Tsai equations are adequately utilized for the estimation of the homogenized stiffness characteristics of the nano-reinforced matrix, considering constant levels of SWCNT agglomeration, orientation, and waviness and taking into account nanoscopic size-dependent characteristics of SWCNTs. The Chamis micromechanical formulae are also applied to explicitly evaluate the six independent elastic properties of the nanocomposite lamina, taking into account temperature and moisture effects. Then, exploiting the Taguchi design of experi-ments, an integrated relationship is established for the estimation of the orthotropic constants of the nano-reinforced composite lamina, under the effect of hygro-thermo-mechanical factors. The macroscopic effect of fiber and SWCNT volume fraction, SWCNT aspect ratio, temperature, and moisture content on the effective mechanical properties, flexural deflection, and design variables of SWCNT-based laminated composite plates is finally investigated, implementing the proposed integrated equation to finite element and continuum models. The obtained results are validated with experimental and theoretical data available in the open literature. To the authors' best knowledge, it is the first time in the open literature that the mechanical properties of laminated composites reinforced by CNTs are predicted using a multiscale-based finite element method considering various hygro-thermo-mechanical factors.