Optimization of soft armor: the response of single-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

Abstract

Typical soft armor systems are constructed of multiple layers of a single fabric type. This empirical research sought to begin optimization of these systems through hybridization, sequencing dissimilar armor fabrics to maximize their ballistic protective performance, by first investigating single plies with a spectrum of properties to determine their behavior and response to impact. Eight individual plain weave fabrics with varying yarns and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene (UHMWPE) yarns and physical and ballistic characterizations were conducted. The ballistic impact tests established the specific energy absorption (SEA) of each fabric across a range of impact velocities (340–620 m·s–1) and the transverse displacement wave velocity across the rear of the fabric was found using digital image correlation. Low cover factor ( Cfab) fabrics (0.74–0.84) consistently showed faster transverse wave speed than the high Cfab fabrics (0.84–0.96) for any given yarn type. The relative SEA of the fabrics varied dependent on both the impact velocity and number of plies impacted. It was found that lower Cfab fabrics had the highest SEA, critical velocity and transverse wave velocity. UHMWPE fabrics were not considered suitable for a woven hybrid system as they had a significantly lower SEA compared to all the para-aramid fabrics. Results indicate that a hybrid system, when considered as a theoretical spaced system, would benefit from higher Cfab fabrics as rearward layers. However, transverse wave results suggest the lower response of these fabrics may inhibit lower Cfab fabrics at the front of a combined hybridized system.

The structural effects on the impact response of ultra-high-molecular-weight polyethylene plain weaves

“…Results of the ANOVA are listed in appendix Table A4. Also, the values of F for all velocities are much greater than the critical value of F (3,16) corresponding to a ¼ 0.05, indicating that the performance of different samples are not statistically similar. It can be seen in Figure 10 that Panels 2 and 4 show a similar performance, which is outperformed by that of Panels 1 and 3.…”

“…The impact results are subjected to analysis of variance (ANOVA), which is shown in appendix Tables A1-A3. It has been found that the values of F for all the velocities are much greater than the critical value of F (3,16) corresponding to a ¼ 0.05, which is 5.29 (the F value is the ratio of the mean squares; it is an estimate of population variance that accounts for the degree of freedom used to calculate that estimate). We are 99% confident (1-a) that the depths of the BFS are not statistically equal for Samples 1-4.…”

“…9,15 Although a woven fabric alone does not provide desirable antiblunt-trauma properties, this type of structure is useful in impeding the progressive failure of fabric plies when placed near the impact face of a panel. There are many studies focused on the optimization of woven-fabric-based panels, 16,17 but the potential of this type of structure in ballistic applications has not been fully explored.…”

Efficacy of various structural forms of disentangled polyethylene laminates against low velocity impact

“…Body armours for ballistic protection are constructed using cross-ply laminates of ultra-high molecular weight polyethylene (UHMWPE) and para-aramid filaments. 1,2 Laminated composites of UHMWPE filaments and linear low density polyethylene (LDPE) film with cross-ply pattern exhibit higher ballistic protection than woven structure based architecture. 3,4 Laminates show the highest impact resistance against small calibration projectiles such as hemispherical, fragments and spheres.…”

Optimization of soft armor: the response of homogenous and hybrid multi-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

“…This study sought to advance previous research on single yarns and plies 24 to generate further understanding of fabric response when combined in a multi-ply system. With limited empirical work available on hybrid systems, where studies have focused more on solely hybrid fiber systems, this research investigated the response of both homogenous and hybrid multi-ply fabrics that varied by fiber type and weave parameters.…”