OVERVIEW OF TEXTILES
simple. The idealizations are relatively simple because most warp and weft yarns are
nominally straight.
A
Figure 2-16. A unit cell for a plain weave.
In a composite of thickness t with n
s
layers of stuffers alternating with n
f
layers of
fillers, the volume fractions of fibers in stuffers and fillers are simply
V
s
= e n
s
/[y
s
ρ
f
t] (2.10a)
and
V
f
= p n
f
/[y
f
ρ
f
t] (2.10b)
where e is the number of ends (stuffers) per unit length in the weft direction and p is the
number of picks (fillers) per unit length in the warp direction; y
s
and y
f
are the yields of the
stuffers and fillers; and
ρ
f
is the fiber density. The volume fraction of the warp weavers can
be written
V
w
= e n
w
c
w
/[y
w
ρ
f
t] (2.10c)
where n
w
is the number of warp weavers between successive columns of stuffers, y
w
is the
yield of warp weavers, and c
w
is a crimp or take-up factor. In principle, c
w
is computed
simply as the ratio of the integrated path length of a warp weaver to its projected length in
