Optimization of the natural frequency of hybrid, multi-scale graphene/fibre reinforced nanocomposite laminates.

Abstract

The optimal solution of the natural vibration problem is investigated in this thesis, for a hybrid, multi-scale graphene/fibre reinforced composite laminate plate. Although several research outputs have been published on the optimization of traditional fibre reinforced composites, the investigation of the reinforcement of these composites by adding a nanomaterial, is still an open topic. The fundamental frequency is optimized within a Sequential Quadratic Programming algorithm. Micromechanics equations are used to produce the effective material properties of the 3-phase laminate plate and finite element analysis is adopted to derive the natural frequencies. Several design variables are considered in the optimization problem, emphasizing in the influence of graphene nanoplatelets‘ weight on the optimal vibration response. Results indicate the optimal distribution of graphene in the laminate for several stacking sequences, boundary conditions and different fibre types (glass or carbon). It is shown that a non-uniform distribution of graphene along the layers of the laminate, results in optimal vibration response. The boundary conditions, as well as the type of fibres (glass or carbon) also affect significantly the natural frequencies.