A numerical study on the influence of quasi-isotropic structures on ballistic performance of para-aramid woven composites

Aimed at improving the ballistic performance of woven fabric reinforced composites, quasi-isotropic structures were developed. This paper reports on the ballistic impact performance and mechanisms of multi-ply para-aramid/epoxy composites with orthotropic and quasi-isotropic structures based on numerical exploration. A validated yarn level model was established using Abaqus® for the investigation of the ballistic performance in terms of the total energy absorption and the ballistic mechanisms regarding energy absorbed in different forms, stress dissipation, damage occurrence time and deformations. The results revealed that para-aramid/epoxy woven composites reinforced by quasi-isotropic structures exhibit improved ballistic performance with new ballistic mechanisms as the reinforcing structures changing from the conventional orthotropic to quasi-isotropic. In this research, up to an 8.9% increase in energy absorption is achieved by the quasi-isotropic composites comparing with the orthotropic composites under the same areal density, caused by enlarged stress dissipation and deformation areas as the yarn directions increase. Limited by the stress propagation in the thickness direction, there exists a maximum number of yarn directions in forming the most energy absorbent quasi-isotropic panel. This research fills the gap between the current study on quasi-isotropic woven composites and their applications for ballistic protections.