The influence of Kevlar surface microstructure on the ballistic resistance of soft armors and their hybrid constructions

Abstract

This study investigates the effects of thermal exposure and silica nanoparticle functionalization on the performance of Kevlar fabrics. We hypothesized that modifying the fabric’s surface roughness through silica treatment would increase the coefficient of friction (COF), consequently enhancing mechanical performance. Microscopic characterization confirmed an increase in COF (77.7% enhancement) following external treatment. While thermal exposure alone increased surface roughness, it resulted in a substantial degradation of the load-carrying capacity and premature failure. In contrast, the silica coating augmented both the surface roughness and stiffness of the Kevlar fibres, leading to improved inter-yarn friction and enhanced mechanical strength (7% and 20% increases in modulus and ultimate stress, respectively). Significantly, the silica-coated samples exhibited negligible changes in mechanical properties after annealing, demonstrating superior retention of material properties and suitability for prolonged field deployment compared to virgin panels. A 3D Finite Element Method (FEM) analysis was conducted to predict the residual velocity, a critical measure of ballistic performance, for an 8-layered armor construction. The analysis included virgin, silica-treated, and annealed fabric configurations. A hybrid construction, incorporating both neat and silica-treated fabrics, exhibited superior ballistic performance across all designs. This highlights the potential of hybrid fabric constructions as an effective strategy for designing soft armor panels for enhanced protection against ballistic threats in various field applications.