## 3 Results and Discussions  
The main target of the optimization process of the wind turbine blade is to find the most optimal design to obtain the maximum power. The Betz method (BEMT) was used to design the primary chord and the twist angle of the blade, but one of the disadvantages of this method it's does not adopt the linear design of the chord and the twist angle. This analysis should be optimized the wind blade according to the linearization approach. Figure 8 shows the initial and the final optimum blade design. Figure 8 shows the difference between the initial design based on the Betz theory (BEM), which is a parabolic curve, and the new design (improved). The improved design is based on the linearization design, where it is a straight line from the root to the tip for both the chord and the twist angle. Figure 9 shows the initial and optimized wind turbine design's power coefficient and power curve. Figure 8: Blade distribution (**a**) chord Length and (**b**) twist angle. It can be noticed from Figure 9 that there is an increase in the power coefficient of the improved design. Where the power coefficient increased at the low TSR from 1 to 4 and is close to the initial design at the medium values of TSR. Later on, the power coefficient decreased for the TSR values greater than 6. This means that the improved design increased the power coefficient at low and high rotational speeds with an average increase of up to 8%. According to the obtained results in Figure 9, it can be concluded that the effect of improving the design to increase the power of the wind turbine is evident at the medium wind speed that starts from 8 m/s, and the improvement in the power at the rated wind speed is 7% compared with the initial design. The steady-state finite element model was used to determine the variation of blade tip deflection and the Von Mises stresses of the wind blade using three different materials to find the most optimal material (with minimum tip deflection). Also, the zones of stress concentration of the blade structure can be determined, and the structure's strength can be improved to obtain an optimal wind blade. Figure 10 shows the distribution of Von-Mises stresses of the wind blade using the proposed materials. Figure 11 shows the distribution of deflection (tip deflection) of the wind turbine blade using different materials. Figure 10: Distribution of Von Mises stresses of (**a**) carbon/epoxy, (**b**) E-glass/epoxy, and (**c**) Braided composite. Figure 9: (**a**) power coefficient with tip speed ratio, (**b**) Power output with wind speed. In order to verify the selected approach to analyze the blade of a wind turbine, the comparations between the results of QBlade software and ANSYS software were made to determine the tip deflection and Von-Mises stresses. High agreement was found between the results of QBlade software and ANSYS software, as shown in Table 6.  
According to the results of Figure 11, it can be seen that the blade bends in the direction of the lift forces due to the low pressure on this side. The Von-Mises stresses for glass fibers and carbon fibers are 39.68 MPa and 40.37 MPa, respectively. Where they are greater than the Von-Mises stresses for the braided composite material (39.75 MPa). It can be noticed that the maximum stresses are concentrated in the middle of the wind turbine blade length, and this indicates that the distribution of the fibers and the thickness is suitable for the structure. Regarding the tip deflection, Figure 11 shows a noticeable difference between the three blades that used different materials. The carbon fiber deflection was 18.29 mm, the glass fiber deflection was 46.46 mm, and the Braided composite deflection was 33.54 mm. However, these results for all cases remain acceptable, where the given distance between the tower and the tip of the blade is about 400 mm, which makes the three materials usable. But the low cost of E-glass compared to the other two materials makes it the most suitable material to manufacture the wind blade.