µTex-10
µTex-20
Unit cell for full thickness
Yarn paths defined as piecewise linear, lying in planes
Yarn cross-sections defined as polygons
TEXCAD Unit cell for single layer
Yarn paths defined as straight and sinusoidal segments
PW
SAT5
SAT8
2D or 3D unit cells for single layer
Yarn paths defined as straight and sinusoidal segments
Yarn cross-sections rectangular
SAWC Unit cell for single layer of plain weave
Yarn paths defined as sinusoidal
Complex geometries formed by stacking units
CCM-TEX Unit cell for full thickness
Yarn paths defined by simple analytical functions
Geometry computed from idealization of textile process
WEAVE Quasi-laminar 3D interlock weaves reduced to laminates
BINMOD Nonperiodic representative volume element
Piecewise linear 1D elements for axial properties of tow segments
Solid effective medium elements for all other properties
Describing the layers of a textile composite as translationally invariant is, of
course, an approximation. Stitching or other through-thickness reinforcement is always
discrete and disrupts translational invariance. The validity of the approximation then
depends on whether the contribution of the through-thickness reinforcement to
macroscopic elasticity can be calculated well enough by replacing the discrete tows by a
smeared out continuum. Experience suggests an affirmative answer for quasi-laminar 3D
interlock weaves [5.8]. In a 2D textile composite, translational invariance is violated by
the internal structure of layers, which is typically that of a plain or satin weave. The
adequacy of the approximation then depends on the extent to which periodic variations of
the fiber orientation within layers can be represented by a uniform, spatially averaged
reduction of the effective layer stiffness. This seems to work quite well in practice for
laminates of triaxially braided plies [5.26].
An example of this alternative approach to quasi-laminar textile composites is the
code called WEAVE, which models 3D interlock weaves. Alternating layers of fillers
and stuffers are modeled in WEAVE as continuous plies. Stuffer and filler waviness can
be allowed for by including an estimate of waviness, which is then represented as a
knockdown in ply stiffness by a rule similar to Eq. (3.1). The estimate of waviness might
come from a theoretical model of the textile geometry, especially if waviness arises from
textile architecture, as in a plain weave; or from measurements of tow loci in
