Finite Element Analysis on Ballistic Mechanisms of Fabric Panel with Air Gaps

The space behind the fabric panel, known as the air gap, has been shown to improve ballistic performance, but the underlying mechanisms remain unclear. This study aims to clarify the ballistic mechanisms of soft fabric panels that incorporate air gaps. We developed finite element (FE) models for non-perforated ballistic impact on 24 layers Twaron® fabrics using a clay backing to simulate deformation. The FE models were validated against experimental data and analytical results. In the FE modelling, the air gap varied from 0 to 8 mm. The results were analysed and computer vision was used to quantify the stress distribution for enhancing the analyses. The findings reveal that as the air gap increases, the clay experiences lower stress and deformation. The ballistic mechanisms lie in: $$\text{①}$$ providing cushioning space; $$\text{②}$$ diminishing initial contact areas; $$\text{③}$$ reducing stress and deformation in the clay. As the air gap increases, the cushioning effect becomes more pronounced. This study lays a theoretical foundation for designing soft body armour with considerably enhanced ballistic performance by simply adjusting the air gap.