Performance of fish scale-inspired armor under impact loading by different impactor shapes: A numerical investigation

Fish scale-inspired armor exhibits numerous advantages over conventional armor plates. This study includes hybrid scale-tissue design with scales inclined at a certain angle. The fish scale-inspired design had a curved radius of 200 mm, a length of 19 mm, a width of 12 mm and an inclination of 10°. The total size of the specimen measured 80 mm × 80 mm × 10 mm. The acrylonitrile butadiene styrene (ABS) material represented the hard scales, while thermoplastic polyurethane (TPU) mimicked the soft tissue. Low-velocity impact scenarios were investigated using the commercially available software LS-Dyna. Scales/ABS were modeled using a plastic kinematic (MAT03) material model, while the tissue/TPU were modeled using a plasticity polymer (MAT89). The effects of indenter shape (hemispherical, conical, and flat head) were studied at an impact energy and velocity of 100 J and 6 m/s. During the impact process, all impactors fully perforated the sample. The performance of the specimen was evaluated based on the specific energy absorption and damage area. The pecific energy absorbed by the conical indenter was the largest, followed by the hemispherical indenter. The bio-inspired specimens resisted the flat indenter early on, while elastic resistance on other indenters gradually increased in the elastic region. The peak forces absorbed by the hemispherical, conical and flat head indenters were 6.1 kN, 5.4 kN and 3.7 kN, respectively. The primary failure modes were shear failure and the tensile breaking of the scales. The present study highlighted the effect of indenter shape on the impact behavior of fish-scale inspired design.