## 4 Results and Discussion
### Mechanical Properties of the UD Composite Tows  
In QNCF lamina, the area except for resin-rich zones can be considered as UD composites, and \(V_{\text{f}}^{\text{t}}\) of the outer and inner plies are different. The QNCF fabric laminate to be analyzed by the mechanical models with \(V_{\text{f}}^{\text{t}}\) = 42.1%. This fiber volume fraction is experimental measurements values in Reference [13]. In this case, according to Equation (1), \(V_{\text{f}}^{\text{t}}\) is shown in Table 3. As the diameter of inner stitching yarn for the QNCF layer is small, the volume of the resin-rich zones is about 3.34% of the total volume of the NCF lamina, which contributes to \(V_{\text{f}}^{\text{t}}\) in the inner \(-45^{\circ}\) and \(90^{\circ}\) lamina close to \(V_{\text{f}}^{\text{t}}\) as shown in Table 3. In addition, the stitching yarn can cause obvious fiber cracking in the outer \(45^{\circ}\) and \(90^{\circ}\), which makes \(V_{\text{f}}^{\text{t}}\) in outer layer higher than that in inner layer. The mechanical properties of composite tows obtained with the micro-scale analysis procedure are shown in Table 4. \(E_{1}^{\text{t}}\), \(E_{2}^{\text{t}}\), \(G_{12}^{\text{t}}\), \(v_{12}^{\text{t}}\), and \(v_{23}^{\text{t}}\) are calculated by the numerical homogenization method, and \(E_{3}^{\text{t}}\) and \(G_{23}^{\text{t}}\) are determined by transversely isotropic material assumption. The stiffness properties of the UD tows estimated by an averaging technique based on the rule of mixtures (RM) [26] is also given in Table 4. This analytical model can calculate the value of \(E_{1}^{\text{t}}\) and \(v_{12}^{\text{t}}\), but has a less accurate result for \(G_{12}^{\text{t}}\) and \(E_{2}^{\text{t}}\) because of the assumption of rectangle section for fiber. Therefore, the analytical values of \(E_{1}^{\text{t}}\), \(v_{12}^{\text{t}}\) are used in this section. According to Table 4, it is clear that the results obtained using the numerical models are consistent with those obtained using the RM. Among the unit cells, composite tows in Cell A has the highest fiber volume fraction (\(V_{\text{f}}^{\text{t}}=48.1\%\)), correspondingly, the longitudinal Young's modulus of the tows is also higher than the other two cases. This is because the longitudinal Young's modulus of composites is a fiber-dominated property. For the numerical predictions of \(E_{2}^{\text{t}}\) and \(G_{12}^{\text{t}}\), the tows with high local fiber volume fraction also has a larger transverse and shear modulus compared with low fiber volume fractions. This can be interpreted that although the transverse and shear modulus of UD composite materials are matrix-dominated, the fiber volume fraction, the ratio of matrix property and fiber property also affects the modulus simultaneously [26]. \"Ref-RM\" is reference value obtained with the rule of mixtures, and \"Ref-FEM\" is reference value obtained by micromechanical model for UD un-stitched composites, and \"In Cell A\", \"In Cell B\" and \"In Cell C\" mean that the composite tows in Cell A, Cell B and Cell C, respectively. The numerical predicted strength properties of composite tows with different fiber volume fractions are shown in Table 5. The analytical values of \(X_{\text{T}}^{\text{t}}\) and \(X_{\text{C}}^{\text{t}}\) based on the RM are also presented for a comparison. The analytical values are obtained by Equations (20) and (21). The existing simple analytical models cannot accurately predict transverse strength and shear strength at the micromechanical level. Therefore, the analytical results of \(Y_{\text{T}}^{\text{t}}\), \(Y_{\text{C}}^{\text{t}}\), and \(S_{12}^{\text{t}}\) are not presented here. \[X_{\text{T}}^{\text{t}}=X_{\text{f}\Gamma}\left[V_{\text{f}}^{\text{t}}+V_{ \text{m}}^{\text{t}}\frac{E_{\text{m}}}{E_{\text{f}\Gamma}}\right] \tag{20}\]  
\[X_{\text{C}}^{\text{t}}=X_{\text{f}\Gamma}\left[V_{\text{f}}^{\text{t}}+V_{ \text{m}}^{\text{t}}\frac{E_{\text{m}}}{E_{\text{f}\Gamma}}\right] \tag{21}\]