Page 110 - 3D Fibre Reinforced Polymer Composites

Micromechanics Models for Mechanical Properties 99

E, = 0.001, E, = 0.001, yV = 0.001, y, = 0.001 and y, = 0.001. The corresponding
engineering constants can be determined using equation (4.10).

Matrix

1

Figure 4.19 FEA model for a simplified 3D orthogonal woven fabric laminate block
(Tan, 1999)

4.4.3.2 Binary Models
Cox et al. (1994) and Xu et al. (1995) developed a finite element model known as the
"binary model" for simulating 3D woven textile composites, as shown in Figure 4.12, in
the elastic regime. As an illustrative example, Figure 4.20 depicts a typical arrangement
of nodes on tow and effective medium elements in a small volume of a layer-to-layer
angle interlock woven composite. In the binary model, the two-node tow elements
represent the axial properties of tows, while the effective medium element represents all
other properties of the tow, resin pockets etc in an average sense. This "effective
medium" element was considered to be homogeneous and isotropic. The