Simulating real FRP microstructures under longitudinal compression: Realistic fibre content, kinking–torsion metrics, and enhanced computational efficiency

Local imperfections in microstructures are a key factor influencing the compressive performance of fibre-reinforced polymer composites (FRPs); this can be investigated through micromechanical finite element (μFE) simulations of representative volume elements (RVEs) reconstructed from computed tomography of real FRP microstructures. This is the first paper that identifies and addresses three key open challenges in μFE simulations of real FRPs under longitudinal compression: firstly, we introduce a new method for generating continuum μFE models of RVEs with high fibre content (up to 55%) and without unrealistic resin-rich boundaries or fibre interpenetration. Secondly, we propose new microstructural metrics to characterise misalignment and twisting, novel deformation metrics to quantify kinking and torsion during compression, and we analyse their relationships. Thirdly, we validate our recently proposed, computationally efficient, shell-beam (SB) methodology at the microstructural level. The results highlight the importance of simulating FRP microstructures with a realistic fibre content and microstructural twist and demonstrate the very good predictive performance of SB models.