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HELICOID INSPIRED COMPOSITES
Quasi-Static Indentation
Reducing the pitch angle with ultra-thin-ply Carbon Fibre Reinforced Polymer (CFRP) helicoidal structures leads to a simultaneous increase in (i) maximum load-bearing capacity (92%), (ii) delay in catastrophic failure (74%) and (iii) energy dissipation (97%).
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The capability of helicoidal structures of dissipating energy through the activation of several sub-critical mechanisms such as helicoidal distribution of delaminations and twisting matrix cracks, allows to overcome the inherent low performance to transverse loading of thin-ply CFRP (with standard lamination sequences).
Growing sub-critical helicoidal damage, as opposed to localised large delaminations and fibre failure, is beneficial because it leads to improved damage resistance and mechanical performance to through-the-thickness loads.
This sub-critical damage can be promoted by reducing the pitch angle down to an optimal value mainly depending on the specific ply thickness and resin-matrix interface.
