Mechanical Behaviour of Vacuum‐Infused <scp>GFRP</scp> Composites at Elevated Temperatures—Influence of Fibre Architecture

ABSTRACT This study addresses the influence of fibre architecture on the mechanical properties of vacuum‐infused glass fibre reinforced polymer (GFRP) composites at elevated temperatures (ET). Laminates with three different fibre configurations—unidirectional (UD), bidirectional 0°/90° cross‐ply (BD), and ±45° off‐axis angle‐ply (OA) – were tested in tension and compression, under steady‐state conditions, at various temperatures up to 300°C. The results were analysed together with data from previous tests on laminates with a multiaxial (MA) fibre layup. The research confirmed the significant temperature dependence of GFRP mechanical properties, especially the more matrix‐dominated ones: at 100°C, compressive strength underwent a major reduction (80%) due to glass transition, particularly for the UD configuration; conversely, at the same temperature, the reductions of tensile strength and tensile and compressive moduli (more fibre‐dominated) were less pronounced, especially for the UD configuration (10%, 20%, and 10%, respectively). For the MA fibre architecture, the behaviour varied between that of the UD and BD configurations, thus emphasising the influence of fibre architecture. The suitability of empirical and phenomenological analytical models proposed in the literature to simulate the experimental results was also assessed and, in general, they provided good fittings. Finally, the experimental data were compared with the design‐oriented temperature conversion factor proposed in CEN/TS 19101:2022: this factor was observed to provide appropriate property reductions for fibre volume fractions in the load direction as low as 20%.