# Alternative Solution for Towing Systems Used in the Automotive Industry
## 3 Experimental Results
### Experimental Determinations on Towbar
In this regard, the graph in Figure 29 shows the considerable differences in values between the materials chosen for this study. This time, the highest values for the towing hooks do not represent advantages, as happened in the diagram where the mechanical strength was represented; on the contrary, they are disadvantages. If from the point of view of mechanical properties the most advantageous hook is the steel one, in terms of specific mass it is the most disadvantageous. It weighs four times more than the carbon fiber tow bar and three times more than every tow bar made of aluminum or aluminum alloy. From the point of view of mass, the carbon fiber towbar is the most advantageous, but the aluminum and siluminum hooks are not without interest either. The aspect regarding the mass of the specimens is the first argument in the study of alternative materials as possible replacements for steel towbars. If the value of the maximum force applied to the towing hook is related to its specific mass, for each individual specimen, comparison indices with a specific unit of measurement  
Figure 29: Performance of alternative material towbars. \(i_{c}=\frac{\bar{r}}{m}\) are obtained. Through these comparison indices, the performance resulting from the ratio of the two analyzed properties of the studied materials is obtained. The obtained index values, but especially their comparative analysis, represent very important arguments in the continuation of this study regarding the identification of alternative materials in the construction of towing systems used for motor vehicles--Figure 30. The higher the index is, the more specifically the material of that index is performing. Observing the dimensions of the indexes mentioned in Figure 30, it can be seen that the material with the most advantageous mechanical properties in terms of strength and mass is carbon fiber mixed with epoxy-type resin, the properties of this material categorically surpassing the properties of steel, but also those of aluminum and siluminium. Comparing the obtained indices of the tow hooks made of siluminium and steel, it can be stated that they are comparable, the material AlSi10 MnMg being slightly superior to steel, and AlSi12 Cu1 Fe slightly inferior. The index corresponding to the aluminum hook is clearly lower than all the other indices of the materials in the analysis. Figure 31 shows the performance of alternative materials compared to the material used today in the construction industry for towing equipment--steel. The graph was plotted by relating the comparison indices of alternative materials with the steel index. Through this report, performance coefficients expressed in percentage are obtained, percentages with values above 100% signifying the overclassification of steel, and lower percentages representing materials with the mentioned properties inferior to those attributed to steel. Regarding the graph in Figure 32, which represents the performance of the materials, it can be said that it expresses a percentage interpretation of Figure 32, the one in which the comparison indexes of the performance of the materials studied in this paper are presented. Figure 31: Performance of towing hooks made of alternative materials. Figure 30: Performance comparison indices of alternative towbar materials. Analyzing Figure 31, it can be seen how the performance of the carbon fiber towbar is over than 250% of the performance of the steel one. In other words, the composite material based on carbon fiber and epoxy resin is 2.5 times more efficient than steel. The AlSi10 MnMg towbar is around 11% more efficient, the AlSi12 Cu1 Fe alloy is around 3% less efficient, and the pure aluminum hook has the lowest performance, around 38% of the steel one.