## 4 Conclusions and Future Work  
In this study, a new model design of a small wind turbine (5 kW) was built from scratch. The main aim is to improve wind turbine aerodynamic characteristics and find the blade model's most optimal design parameters. It enhanced the power coefficient, reaching the value of 0.47 when TSR was equal to 6 for the optimal design. In other words, the efficiency increased by 8% compared to the initial design. At the same time, the power of the optimized wind turbine increased by 7% at rated wind speeds. A new finite element model was built for a small wind turbine blade of 5 kW based on the optimized wind turbine blade design. The steady-state and modal problems solutions were found to obtain the optimal material for the wind blade.  
Further, it was found that the minimum tip deflections were 18.29 mm, 33.54 mm, and 46.46 mm, corresponding to the blade being made of carbon fiber material, Braided composite, and E-glass material, respectively. Hence, it can be concluded that the optimal material in terms of the magnitude of deflection is carbon fiber material. The modal analysis results showed that the natural frequencies of wind blade made from E-glass has the lowest natural frequencies (1 st: 16.17 Hz and 2 nd: 38.46 Hz). On the other hand, the wind blade made of carbon fiber has the largest natural frequencies (1 st: 29.58 Hz and 2 nd: 70.20 Hz).  
In future works, some important problems should be investigated deeply. Fatigue is one of the main failure problems of wind turbine blades during operating periods, especially when it has a crack in the structure [29]. So, it's necessary to study the fatigue of the wind turbine using different materials under normal and extreme operating conditions. In recent research, nanotechnology has been adopted to improve composite materials [30]. This composite material can be applied to small wind turbines to enhance their efficiency. The other problem of wind turbines that should be investigated is the annoying sounds and noise during rotation in order to reduce it.  
The climate of the locations of wind turbines varies from one site to another, from very hot to very cold. Thus, the study of the influence of climate on the dynamic characteristics of the wind turbine blade [31] is considered an essential issue as well.  
Formal analysis, investigation, writing--review and editing, K.D.; methodology, resources, M.T.G. and H.S.S.; resources, funding acquisition, writing--review and editing, A.N.J.A.-T. and A.M.A.; writing--review and editing, supervision, O.I.A.; writing--review and editing, H.M. and A.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The study did not report any data.  
The authors acknowledge the \"System Technologies and Engineering Design Methodology\"--Hamburg University of Technology for supporting research and providing facilities.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mode**} & \multicolumn{3}{c}{**E-glass/Epoxy**} & \multicolumn{3}{c}{**Braided Composite**} & \multicolumn{3}{c}{**Carbon/Epoxy**} \\ \cline{2-9}  & **QBlade** & **ANSYS** & **Difference \%** & **QBlade** & **ANSYS** & **Difference \%** & **QBlade** & **ANSYS** & **Difference \%** \\ \hline
1 & 15.13 & 16.17 & 6.43 & 19.80 & 20.06 & 1.30 & 28.29 & 29.58 & 4.36 \\ \hline
2 & 36.19 & 38.46 & 5.90 & 48.32 & 47.70 & 1.30 & 74.11 & 70.20 & 5.57 \\ \hline
3 & 45.39 & 48.94 & 7.25 & 63.41 & 60.71 & 4.45 & 92.20 & 89.50 & 3.02 \\ \hline
4 & 99.56 & 98.34 & 1.24 & 130.59 & 122 & 7.04 & 185.14 & 179.83 & 2.95 \\ \hline
5 & 165.82 & 161.01 & 2.99 & 196.43 & 199.76 & 1.67 & 289.23 & 294.56 & 1.81 \\ \hline
6 & 172.93 & 169.09 & 2.27 & 221.15 & 209.78 & 5.42 & 315.67 & 309.51 & 1.99 \\ \hline \hline \end{tabular}
\end{table}
Table 7: The comparison of Frequencies using different materials.