▎ 摘　　要

Today, light-weighting for energy efficiency without sacrificing safety and performance attributes has become a primary focus in the automotive industry. In the field of modelling graphene nanocomposites' structural ap-plications under severe loading conditions, literature is limited. In addition, the existing work only employs the so-called one-site (OS) modelling. This study develops an approach to study 3-phases hierarchical fibres/gra-phene nanoplatelets (GNPs)-reinforced polymer matrix composites utilising OS modelling and what is known as multi-site (MS) modelling. The MS modelling accounts for material anisotropy considering the interaction be-tween neighbouring inclusions. Applicability of both models is then assessed for automotive components' crashworthiness response under combined mechanical and rate-dependent plasticity or viscoplasticity behav-iours. A coherent micromechanical design is employed with elastic platelets and elasto-viscoplastic matrix as-sumptions. The micromechanics modelling combines rate-dependent constitutive laws and thermomechanical properties for the nonlinear response of composite materials. The heterogeneous material problem is resolved in the first instance for a thermoelastic case. The thermomechanical kinematic integral equation is used to derive the strain concentration tensor. Using the generalised Mori-Tanaka (GMT) homogenisation scheme, effective thermomechanical properties are obtained. For the nonlinear behaviour, a linearisation of the classical J2 rate-dependent model is considered with an isotropic hardening. Based on an implicit integration scheme, a consistent tangent modulus is obtained and serves as a uniform modulus for homogenisation of the rate-dependent ther-momechanical composite material. An application is therefore performed on a short glass-fibres/graphene nanoplatelet/ Polyamide-Nylon 6 (GNP/PA6) composite. The current study's archival value is to provide an auspicious approach for a consistent design and application of this category of materials for automotive struc-tural components.