Ballistic Performance of Bio-mimicked Nacreous Protection System on Concrete Target: A Numerical Investigation

Inspired by the staggered pattern and global energy dissipation mechanism of nacre layers, an aluminum alloy (AA) composite layer structure was designed on the concrete surface to improve its ballistics performance in the numerical investigation. This low-weight 7075-T651 AA composite structure is of 12 mm thickness, having layers of sheets bonded together using stress criteria corresponding to epoxy resin. A numerical model was developed for reinforced concrete using an explicit dynamics solver and validated against experimental penetration depth and damage data. This model is extended to develop surface protection of AA plates. The total thickness of the AA composite plate is maintained at 12 mm. Parametric analysis is done for plain reinforced concrete, with an AA bulk plate and 4, 6 layers of AA nacre layers to study the ballistics performance. A significant residual velocity decreased for nacre layer structures compared to the plain bulk plate. Due to the layered and staggered arrangement, a larger area of delocalized damage and debonding between plates was observed in the nacre-like plates. Energy characteristics improved for the four-layer nacre structure compared to the bulk plate. This paper will provide insight into enhancing designs for better ballistics performances in future.