Effect of basalt intraply hybridization on the damage tolerance of flax laminates. Experimental analysis and analytical modeling under low-velocity impact

Since natural fiber composites have a high potential as an alternative to synthetic materials, their mechanical properties must be investigated under different loading modes. In this paper, flax, basalt and hybrid flax-basalt/epoxy resin composite laminates are experimentally characterized and their behavior under low-velocity impact conditions is investigated. Analytical models, on their part, represent a low-cost and low-time consuming tool to provide initial considerations on the mechanical behavior of these relatively new composites in load-bearing applications. Therefore, in this work, analytical models previously introduced for synthetic fiber laminates are used to provide an approximation of the load–displacement curve resulting from a low-velocity impact on flax, basalt and flax/basalt hybrid laminates. In particular, an attempt is made to predict the descending phase of the load–displacement curve. To validate the theoretical results, an experimental campaign was carried out with different impact energies from 2.5 J to 10 J at room temperature. The experimental results showed a significant improvement in the quasi-static mechanical properties and damage tolerance of the hybrid composites compared to flax-based laminates. The analytical results confirmed that the presented models are well able to predict the response of natural fiber composites during loading and unloading phases for all considered material configurations.