## 4 Results
### Determination of the Degree of Damage to the CB Depending on the Magnitude of the Deflection  
The evaluation of the test also included a visual inspection of the CB and the determination of the degree of CB damage. The observed variable damage characterizes the severity of the damage to the sample at the point of impact of the impactor. Damage was classified into two basic categories (Table 1): no damage (Figure 8a, Damage 0), non-significant (partial) damage (e.g., damage to the upper or lower covering layer without skeletal damage, Damage 1, Figure 8b), and serious damage (damage to the upper covering layer, skeleton, and lower covering layer of the conveyor belt sample, Damage 2, Figure 8c, or puncture Damage 3, Figure 8d). The visual assessment shows that in the experiment without the support system, significant damage was not caused to the CB samples throughout the measurement range. At greater heights and higher weights, there was minor damage to the upper or lower covering layer. Out of a total of 78 samples, 48 samples were classified as Damage 0 (61.5%) and 30 samples as Damage 1 (38.55%). Non-significant damage (Damage 1) occurs when the magnitude of deflection of the CB is below a value of approximately \(-100\) mm (Figure 9). Figure 8: Types of CB damage. Figure 9: Occurrence of damage depending on the CB deflection (without a support system). When the support system was used, at some impactor weights and impact heights, the test sample was severely damaged or even destroyed (punctured). Of the total 67 samples, 23 samples were classified as Damage 0 (34.3%), 16 samples as Damage 1 (23.9%), 17 samples as Damage 2 (25.4%), and 11 samples as Damage 3 (16.4%). Serious damage to the body of the test sample occurred as early as an impactor weight of 60 kg from an impact height of 2 metres. The situation in which severe damage occurred is shown in Figure 10 at the site of significant curve breaks. The results of the video analysis showed that serious damage (Damage 2, Damage 3) occurred if the measured value of the CB deflection was less than \(-\)70 mm (Figure 10). A classification model of the damage to the CB with a support system was created using a decision tree. The training group consisted of 78 test samples of conveyor belts without a support system and 67 test samples of conveyor belts with a support system. The classification criterion is the variable Damage, which has four classification categories: Damage 0 (D0), Damage 1 (D1), Damage 2 (D2), and Damage 3 (D3). Three other input variables (Deflection, Height, and Weight) were used to characterize the examined samples of conveyor belts (Table 2). We considered the variables (Height, Weight, and Damage) as categorical variables and deflection as a continuous variable. The results of the decision trees for both cases \begin{table}
\begin{tabular}{l l} \hline \hline
**Variables** & **Description** \\ \hline Dependent Variables & \\ Damage & Damage type: \\  & Damage 0 (D0), Damage 1 (D1), \\  & Damage 2 (D2), Damage 3 (D3) \\ Independent Variables & \\ Height & Impact height (m) \\ Weight & Weight of impactor (kg) \\ Deflection & Deflection amount (mm) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of variables. Figure 10: Occurrence of damage depending on the CB deflection (with a support system). are shown in Figures 11 and 12. The first division occurred according to the deflection magnitude of the CB. The graphs were constructed using the R package.