Visco-elastic and Visco-plastic Strain-Rate Dependent Material Models for Bioinspired UHMWPE-Kevlar armour structures.

This work presents a fish-scale bioinspired armour concept involving Kevlar fabric and UHMWPE (Ultra-High Molecular Weight Polyethylene) discs as a sandwich structure to enhance ballistic energy absorption. The novelty lies in coupling bioinspired structural design with viscoelastic and viscoplastic, strain-rate-dependent material modeling to accurately predict residual bullet velocity and target deformation. UHMWPE behavior was characterized through quasi-static tensile and compressive tests and Split Hopkinson Pressure Bar experiments. The measured rate-dependent response was implemented in LS-DYNA simulations of ballistic impact, validated against experimental ballistic impact tests. The study extends ballistic modeling beyond metallic targets by developing a rate-dependent analytical model for bioinspired UHMWPE–Kevlar armour structures. The results highlight the synergistic effect of geometry-induced load distribution and rate-dependent material response, demonstrating the potential of biomimetic architectures for lightweight, flexible, and high-performance ballistic protection systems.