Influence of boundary conditions on the ballistic performance of high-strength fabric targets

Abstract

High-strength fabric is commonly used in personnel protection systems against small arms projectiles and fragments. An understanding of the characteristics of high-strength fabric under ballistic impact would provide useful insights for fabric armor design. A numerical model is formulated and used to study the perforation of square cross-woven fabric targets when the fabric is (i) clamped along all four edges with its yarns aligned parallel to the edges, (ii) clamped along all four edges with yarns running 451 to the edges and (iii) clamped along two edges with yarns aligned parallel to the edges. In addition, high-speed ballistic tests are carried out to validate the computational results. It is found that the ballistic resistance of such systems is sensitive to boundary conditions and yarn orientation. Targets that are unclamped on two edges can absorb more impact energy than those with all four sides clamped. Orientating the yarns 451 to the clamped edges can improve energy absorption significantly. Stresses in primary yarns (those in contact with the projectile) increase rapidly when their ends are clamped; this leads to rapid failure at the impact point and a lower-energy absorption. For fabrics clamped along four edges, the regions near the four corners are not stretched during impact if the yarns are parallel to the edges, whereas clamping with the yarns 451 to the edges facilitates energy dissipation by the entire fabric. It is also observed that slippage at clamped edges contributes to higher energy absorption by fabric targets. r

Simulation of Large Fragment Impacts on Shear-Thickening Fluid Kevlar Fabric Barriers

“…Such slipping would be most significant for targets tested near their ballistic limit, when boundary conditions exert the most influence on the test results. Note that the effect of target slipping would be to extract energy from the projectile; neglecting this effect would tend to overestimate residual velocities for the thickest targets [36]. This possibility is consistent with an observed trend in the simulations, and it is independent of the material (neat or STF) type.…”

Response of woven and laminated high-strength fabric to oblique impact

“…The ballistic response of high-performance fabrics has been a topic of extensive research over the past three decades, which include analytical studies [1e6], experimental investigations [7e12] and numerical simulation [8,13e20]; comprehensive reviews have been presented by Cheeseman and Bogetti [21] and Tabiei and Nilakantan [22]. Results show that the impact resistance of these fabrics is influenced by a number of parameters, including material properties of the constituent fibre [13,22], fabric structure [7,12], projectile geometry [10,11], impact velocity [14,23], boundary conditions [7,8,24,25] and friction [12,26,27].…”

Impact of woven fabric: Experiments and mesostructure-based continuum-level simulations

“…Cunniff (1992), Walsh et al (1998), Shim et al (1995), and Zeng et al (2005), among others, also observed slip of the fabric in experiments. The fabric slipped a maximum of 2-5 mm of from each side of the frame, during both the square and circular cut-out tests.…”