Topological design and experimental characterisation of continuous fibre-reinforced composite multiscale structures

Abstract

In this study, a topology optimisation method is developed for designing a novel multiscale structure (MSS) with continuous fibre-reinforced composite materials (CFRCs) to achieve superior mechanical and functional performance. An interpolation function for the elastic matrix is established based on the discrete material optimisation (DMO) model to formulate the multiscale optimisation problem. The sensitivities of the objective function and constraints with respect to the design variables are derived to update macro and micro design variables, while the fibre orientations are determined by the principal stress directions. A Messerschmitt–Bölkow–Blohm (MBB) beam case was used for both parametric analysis and experiments, in which three structural configurations: mono-scale structure (MOS) with CFRC, MSS (without CFRC), and MSS with CFRC (MSC) were comparatively investigated. Experimental tests showed that the initial stiffness and peak force of MSC are ∼118.8 % and ∼65.7 % higher than those of MSS, respectively, demonstrating the significant positive effect of fibre reinforcement. Meanwhile, the residual toughness of MSC increases by ∼101.4 % as compared with MOS. Furthermore, frequency response function (FRF) tests and numerical modal analyses showed that the natural frequencies of MSC are generally higher (averagely ∼17.3 %) than those of MOS, indicating that the multiscale configuration enhances the dynamic mechanical performance. These findings have confirmed the effectiveness of the proposed method and provided a useful strategy for acquiring high-performance fibre-reinforced composite multiscale structures.