JEC COMPOSITES MAGAZINE - Issue #79 - March 2013 - 92

fabric
added cost. This structure ensures that the fabric is woven using
the optimised weave but with extra gripping on the constituent
yarns. Yarn pulling-out tests were carried out in order to examine the effectiveness of the structure used in GRPG-1.

gripping to its constituent yarns. The first samples of this type
of fabric were developed based on hand-loom weaving. The
fabric can be manufactured on power looms with minor and
necessary modifications to the loom.

Experimental evaluation of 2D fabrics
Yarn gripping effectiveness
For comparison purposes, the 2D broad fabric with enhanced
yarn gripping, GRPG-1, was tested and compared with four
narrow fabrics with natural selvedge, which were shown to
be advantageous over the fabric stripes without weft yarn
gripping [17]. All fabrics were evaluated on the amount of
materials needed to stop the projectile and on the depth of the
backface signature. Figure 2 shows a comparison between the
two groups of ballistic fabrics.

Fig. 1: Resistance to yarn pull-out from GRPG-1 fabric

Figure 1 shows the load-displacement relationship between
the plain and GRPG-1 ballistic fabrics. The GRPG-1 fabric
demonstrates higher resistance to yarn pull-out during the
process. It is noted that the GRPG-1 fabric offers 40% more
resistance than its plain counterpart. According to Lyons [11],
fabrics with this feature would contribute to faster longitudinal propagation and therefore would dissipate impact energy
more effectively. After the yarn was pulled out from the fabric,
the plain fabric and the GRPG-1 fabric demonstrated similar
yarn movement with similar resistance. This is advantageous
for the GRPG-1 fabrics as it shows that, despite the tighter
gripping on yarns, the new fabric also permits the necessary
yarn displacement during fabric deformation to absorb impact
energy.
GRPG-2 is another 2D woven fabric that offers enhanced

From the study on narrow fabrics, it was concluded that
narrow fabrics with natural selvedge demonstrated better
ballistic properties than their narrow stripe counterparts
[Cork and Forster][Sun and Chen]. However, the problem of
narrow fabrics for ballistic protection is that they cannot offer
the material continuity required for impact energy dissipation. GRPG-1, as an engineered fabric, offers both material
continuity and extra yarn gripping. Figure 1(a) compares the
two types of fabrics on the areal density needed to block the
projectile under different levels of impact energy. It shows
that the GRPG-1 fabric can stop the impacting projectile with
almost the lowest areal density regardless of the impact energy
applied. Figure 5(b) shows clearly that the GRPG-1 fabric
is the best in absorbing and dissipating the residual impact
energy as it relates to the smallest depth of backface signature.
To summarise, the engineered GRPG-1 fabric based on the
new engineering concept out-performs the narrow fabrics
with natural selvedge and is a strong candidate material for
ballistic protection.

Fig. 2: GRPG-1 vs narrow fabrics: (right) Materials needed to stop penetration, (left) Depth of backface signature

92 jec composites magazine / No79 March 2013

JEC COMPOSITES MAGAZINE - Issue #79 - March 2013

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