Low-Velocity Impact of carbon, flax, and hybrid composites: Performance comparison and numerical modeling

In recent years, composite materials have assumed an increasingly dominant role in various industrial sectors, combining lightweight with optimal mechanical properties. In this context, natural fibers are essential for the development of eco-friendly composites, ensuring a balance between performance and sustainability via hybridization. This study provides an experimental and numerical analysis on composite laminates subjected to Low-Velocity Impact (LVI) tests at different energy levels, after an initial mechanical characterization of the materials. Carbon and flax fiber fabrics are chosen as reinforcements embedded in a toughened epoxy resin, as well as in two hybrid configurations; two different stacking sequences are also investigated, with the layers placed at 0°and in a quasi-isotropic (ISO) orientation. Hysteresis curves and energy absorption capability – in terms of specific energy absorption (SEA) – are then discussed and compared to each other, along with cross-shaped damage propagation on fracture surfaces. Numerical finite element (FE) models of tensile, compressive, and LVI tests are designed and solved using LS-DYNA software. In particular, tensile and compressive ones are carried out to calibrate the material cards, which have subsequently been adopted in the LVI models. The results obtained not only show an agreement between the experimental response and the simulated one, but also provide a complete investigation of different materials and orientations under LVI in view of future applications, highlighting the possibility of designing structural components to absorb energy in hybrid composites reinforced with natural fibers.