# Use of New and Light Materials in Automotive Engineering for Towing System
## 5 Detailing the Experimental Process for the Five Solutions
This theory has been used for bending stress distributions that are hyperbolic, passing through 0 on the axis of the center of curvature. Another meaning of neutral axis displacement is that the stress inside the radius of curvature is greater than the stress outside the radius of curvature (stress concentration \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{\begin{tabular}{c} **Maximum** \\ **Force** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Maximum** \\ **Displacement** \\ **[mm]** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Maximum** \\ **Stress [MPa]** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Specific Mass** \\ **[Kg/m\({}^{3}\)]** \\ \end{tabular} } \\ \hline Carbon fiber & 14.436 & 27.65 & 354.36 & 780 \\ \hline Steel S355 & 24.724 & 13.85 & 606.89 & 3.400 \\ \hline Aluminum Al99.7 & 5.134 & 54.60 & 71.31 & 1.050 \\ \hline AlSi10 MnMg & 8.504 & 18.80 & 208.74 & 1.050 \\ \hline AlSi12 Cu1 Fe & 7.401 & 15.40 & 181.67 & 1.050 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental measurements of towbars. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Method**} & \multirow{2}{*}{\begin{tabular}{c} **Area of Interest** \\ **The Inside of the Radius of** \\ **Curvature of the Towbar, \(\Sigma_{\text{int}}\)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **The Outside of the Radius of** \\ **Curvature of the Towbar, \(\Sigma_{\text{ext}}\)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **The Ends of the Strength Beam** \\ **of the Entire Towing System** \\ \end{tabular} } \\ \cline{2-2}  & **[MPa]** & **[MPa]** \\ \hline Classical calculus & 188 & 117.04 & 63.82 \\ \hline FEM & 184.9 & 118.6 & 63.4 \\ \hline Fotoelasticimetry & 164.6 & 104.4 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The critical stresses obtained by the 3 methods. effect). Also, regarding the behavior of the samples, it can be said that those from CF and AAl are very brittle, with very low elongation coefficients, and their characteristic curves almost linear compared to that of the steel and pure aluminum samples. A major disadvantage in the behavior of these samples is their lack of homogeneity, and there are considerable differences between the samples of the same type with the exception of those from S355; with a well-documented preparation of the acquisition processes, much more satisfactory results could be obtained in this regard. Analyzing the behavior of the samples, there was interest in making towing hooks from CF mixed with epoxy resin, AlSi10 MnMg alloy (with this material showing better performances than that of AlSi12 Cu1 Fe), but out of the desire to confirm, a hook was also made from the second type of AAl, and, of course, they were compared with a hook made of S355 steel. Considering the interest in studying the behavior of a towing hook with extreme displacement, without breaking and without imposing material damage hazards on the mechanical strength testing machine, it was decided to make a pure aluminum towing hook (Al99.7%), as it has been observed that these are very malleable and do not break. Calculations showed that the minimum force acting on the towing hook must be 7.5 kN to validate the required strength of the hook during car braking. By far the best strength was shown by the steel towbar, but the CF towbar showed very advantageous behavior, with the breaking force being almost double the breaking force required for product validation. The AAl towbars came very close to the validation limit, with the AlSi10 MnMg one passing the test and slightly exceeding the required force, while the other was more deficient, as were the specimens in that alloy, failing the test but being very close to the limit. In terms of sphere displacements, the most advantageous behavior was shown by the steel hook with the smallest displacement, with the CF towing hook having the most generous deflection.