## 4 Discussion  
Based on the simulations performed in MSC Adams 2019, the maximum load applied to the wheels of the alternative SkidCar system was determined. The load value obtained this way, was used as the input value of the ASC frame load to perform strength FEM analyses in SolidWorks 2022. After comparing the results of the linear analyses of the original design of the frame crossbars for, respectively, forward, reverse and both sides driving modes, it was assessed that the highest stress on the frame occurs when the car moves in the transversal direction with the wheels turned away from the car. This driving mode was considered in all other stress-deformation analyses of the original and optimized frame designs. After evaluating the strength of the original frame solution, the frame complies with the limit states point of view, but the stress at several locations exceeds the maximum allowable stress. Through an optimization process, frame reinforcements were added to the areas with a high-stress concentration. This allowed the thickness of the  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Original Thickness** & \begin{tabular}{c} **Thickness after the** \\ **Optimization** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Original Weight** \\ **(kg)** \\ \end{tabular} & \
\begin{tabular}{c} **Weight after the** \\ **Optimization** \\ **(kg)** \\ \end{tabular} &
\begin{tabular}{c} **Difference** \\ **(\%)** \\ \end{tabular} \\ \hline
5 & 4 & 32.6 & 29.1 & 10.5 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Comparison of thickness and mass of crossbars, before and after design optimization.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Original Thickness** & \begin{tabular}{c} **Thickness after the** \\ **Optimization** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Original Weight** \\ **(kg)** \\ \end{tabular} & \
\begin{tabular}{c} **Weight after the** \\ **Optimization** \\ **(kg)** \\ \end{tabular} &
\begin{tabular}{c} **Difference** \\ **(\%)** \\ \end{tabular} \\ \hline
5 & 3 & 32.6 & 24.0 & 26.3 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Comparison of the thickness and weight of frame parts using original steel S235 JR solution and stronger S355J0 steel.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Original Thickness** & \begin{tabular}{c} **Thickness after the** \\ **Optimization** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Original Weight** \\ **(kg)** \\ \end{tabular} & \
\begin{tabular}{c} **Weight after the** \\ **Optimization** \\ **(kg)** \\ \end{tabular} &
\begin{tabular}{c} **Difference** \\ **(\%)** \\ \end{tabular} \\ \hline
5 & 6 & 32.6 & 17.8 & 45.4 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Comparison of the thicknesses and weights of the frame parts using the steel of the original S235 JR solution and the aluminium alloy EN AW-606 T6.  
crossbar wall to be dropped to 4 mm, thereupon ensuring a decrease in the crossbar weight, by 10.5%, using the current material (S235 JR), while maintaining the original strength of the frame. From the above findings, it is clearly visible that during further frame adjustment, it is possible to reduce the wall thickness from 5 mm to 3 mm using S355J0 steel, and thus save the weight of 26.3% compared to the original state. When using EN AW-6060 T6 material, the thickness of the crossbar profile had to be increased to 6 mm. However, the weight of the crossbar decreased by 45.4%, while maintaining the original strength.