Quasi-static penetration property of laminates with hybrid cores having interlocking skeletons formed by crocheting the twisted 316 L/Kevlar fiber ropes

The present work aimed to investigate the quasi-static properties and energy absorption of fibre-metal laminates (FMLs) with novel hybrid cores by finite element analysis and experiments. The cores were formed by crocheting continuous fiber ropes twisted from 49 ultra-fine soft stainless steel fibers or 1000 Kevlar fibers, which are mesh fabrics with interwoven and interlocked knots, and rope skeletons linking the knots. Results indicated that while flexible cores have lower peak resistance, they offer high ductility and deformation recovery. Although the core's energy absorption is low, when combined with metal face sheets, a significant composite effect emerges, contributing 40–50 % to total energy absorption. The specific energy absorption per unit mass increases across all these types of FMLs compared to metal face sheets, with double Kevlar cores demonstrating the highest specific energy absorption. The FMLs studied in this paper have considerable application potential in the field of modern protective structures that achieve both protective performance and lightweight.