A comprehensive review of advanced manufacturing techniques, ai-enabled design, and mechanical characterization of nature-inspired helicoidal hybrid composites for impact-resistant applications

Helicoidal structures mimic nature and are evident in plant cell walls, lamellar bone, and the shell structures of mantis shrimp and beetles. These nature-inspired helicoidal composites are widely used in impact-resistant applications. Traditional hand-layup methods for producing layered helicoidal composites can introduce defects such as gaps, overlaps, and wrinkles, which can be mitigated using Automated Fiber Placement (AFP). Optimizing AFP process parameters, including pressure, temperature, and layup speed, is crucial. While experimental optimization is costly and time-consuming, Artificial Intelligence (AI)-based design offers a more efficient alternative. This narrative review explores the inspiration behind helicoidal structures and their application fields. It also covers advanced manufacturing of hybrid long-fiber layered composites using AFP + autoclave/hot press, ceramic filler-based nanocomposites using direct ink writing (DIW), and multi-walled carbon nanotube (MWCNT)-based nanocomposites using digital micromirror device (DMD). Furthermore, it discusses the roles of machine learning and deep learning, coupled with finite element modeling, in minimizing process-induced defects. Compared with conventional AFP inspection techniques such as laser profilometry and thermography, a defect-detection algorithm based on PointNet + + , a convolutional neural network (CNN), can be tailored for 3D point cloud segmentation, offering a cost-effective, user-friendly alternative. Next, the mechanical and microstructural properties of helicoidal composites, compared with those of traditional laminates, are discussed to evalaute impact performance. Helicoidal composites with low inter-ply angles up to 20° consistently outperform conventional lay-ups under quasi-static and impact loading, due to a crack-twisting mechanism and superior out-of-plane properties. Incorporating nylon 6 powder microparticles into carbon/epoxy and glass/epoxy helicoidal composites subjected to impact loading significantly improves their toughness through self-healing, compared with virgin helicoidal composites. Carbon/epoxy helicoidal composites with low inter-ply angles of up to 9° are prone to extensive matrix cracking and minor fiber damage, while self-healing in carbon/epoxy composites also helps minimize matrix cracking but does not reduce fiber damage. In contrast, self-healing significantly decreases overall damage in glass/epoxy composites. Self-healing is more effective at eliminating damage in glass/epoxy than in carbon/epoxy, primarily because the former exhibits higher ductility (% elongation) than the latter.