Modelling and Optimization of Natural Fiber Tubular Structures subjected to axial crushing
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Composite materials are widely used in several sectors, including transportation one. Their lightweight addresses the ever-increasing environmental and sustainability concerns by reducing fuel consumption and emissions. Furthermore, composite structures present higher performance in terms of energy absorption during an impact event than metals. Moreover, among the composite materials, natural fiber-based materials are increasingly used in various applications as an ecological alternative to traditional synthetic ones. For these reasons, in recent years, the automotive industry has been increasingly concerned with delivering lightweight and crashworthy composite structures to address both vehicle performance and safety issues. Crashworthy components acting as energy absorbers are typically thin-walled tubes. This study focuses on the crashworthiness performance of flax/epoxy circular tubes under axial crush as a possible alternative to carbon/epoxy ones. The aim is to investigate, experimentally and numerically, the energy absorbing capabilities of such natural fiber composite tubes. A finite element (FE) modelling of these composites, created and simulated with explicit LS-DYNA software, is developed to reproduce their crushing phenomenon, with material properties determined from mechanical tests. In this regard, a trigger mechanism is provided for each specimen to localize the stress and initiate failure. This work presents further an optimization study to identify some optimal material and geometric parameters. After that, the numerical and experimental results are compared to validate the model’s effectiveness. The model demonstrated its good predictability and the improvement allowed by the optimization strategy. The obtained results suggest that flax/epoxy tubes may be potentially used as energy absorbers.