## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Rotor Material** & \begin{tabular}{c} **Yield Stress** \\ **(RPM)** \\ \end{tabular} & \begin{tabular}{c} **Stored Energy** \\ **(Wh)** \\ \end{tabular} & \
\begin{tabular}{c} **Rupture Stress** \\ **(RPM)** \\ \end{tabular} &
\begin{tabular}{c} **Stored Energy** \\ **(Wh)** \\ \end{tabular} \\ \hline Mild steel & 50,700 & 14.29 & 68,740 & 26.27 \\ Titanium alloy & 125,700 & 51.7 & 137,000 & 61.42 \\ CFRP (230 GPa) & - & - & 952,500 & \(1156.63\) \\
**Hybrid structure** & & & & \\ Mild steel—3 mm CFRP & 55,350 & 15.76 & 75,080 & 29 \\ Mild steel—5 mm CFRP & 57,150 & 15.94 & 77,520 & 29.3 \\ Mild steel—10 mm CFRP & 60,600 & 15.67 & 82,140 & 28.8 \\ Mild steel—20 mm CFRP & 73,500 & 17.6 & 99,650 & 32.32 \\ Titanium alloy—3 mm CFRP & 137,580 & 58.28 & 147,900 & 67.35 \\ Titanium alloy—5 mm CFRP & 141,260 & 59 & 151,500 & 67.85 \\ Titanium alloy—10 mm CFRP & 144,850 & 56 & 155,350 & 64.44 \\ Titanium alloy—20 mm CFRP & 163,860 & 59.1 & 175,800 & 68 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Stored energy according to the flywheel structure. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Rotor Material** & \begin{tabular}{c} **Yield Stress** \\ **(RPM)** \\ \end{tabular} & \begin{tabular}{c} **Yield Stress** \\ **(km/h)** \\ \end{tabular} & \
\begin{tabular}{c} **Rupture Stress** \\ **(RPM)** \\ \end{tabular} &
\begin{tabular}{c} **Rupture Stress** \\ **(km/h)** \\ \end{tabular} \\ \hline Mild steel & 50,700 & 955.67 & 68,740 & 1295.72 \\ Titanium alloy & 125,700 & 2369.4 & 137,000 & 2582.4 \\ CFRP (230 GPa) & - & - & 952,500 & 17,954.2 \\
**Hybrid structure** & & & & \\ Mild steel—3 mm CFRP & 55,350 & 1043.32 & 75,080 & 1415.22 \\ Mild steel—5 mm CFRP & 57,150 & 1077.25 & 77,520 & 1461.22 \\ Mild steel—10 mm CFRP & 60,600 & 1142.28 & 82,140 & 1548.3 \\ Mild steel—20 mm CFRP & 73,500 & 1385.44 & 99,650 & 1878.36 \\ Titanium alloy—3 mm CFRP & 137,580 & 2593.32 & 147,900 & 2787.85 \\ Titanium alloy—5 mm CFRP & 141,260 & 2662.7 & 151,500 & 2855.7 \\ Titanium alloy—10 mm CFRP & 144,850 & 2730.36 & 155,350 & 2928.28 \\ Titanium alloy—20 mm CFRP & 163,860 & 3088.7 & 175,800 & 3313.75 \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Maximum RPM and peripheral speed values of different rotor materials. composite hybrid structure as 4 and all carbon fiber as 5 in terms of material and ease of processing. The comparison table is prepared by looking at the maximum RPM equivalent to the rupture point stresses. A ranking is made depending on the Likert scale. The rotor made of manufacturing steel is the heaviest rotor, as well as the material with the lowest RPM, manufacturing cost, material cost, and energy storage capacity. Carbon fiber is seen to be the opposite. At the same time, the rotor with the highest carbon thickness is seen to be the lightest rotor in the hybrid structure. Although multi-rim rotors exhibit up to 200% higher energy density compared to steel and titanium rotors, their reliability may be compromised due to their complex structure. The metal core and the carbon fiber layers--either bonded or wound around it--may gradually separate over time as a result of aging, leading to further degradation. Hybrid rotor systems are anticipated to achieve higher rotational speeds than solid rotors. This advancement necessitates the fabrication of multi-layer systems with more precise and advanced manufacturing technologies.