## 3 Results and Discussion
When it comes to frequent iterations (changes to the body or selection of alternative materials), the beam modeling approach is preferred over the solid one, although to obtain higher accuracy results, it is advisable to reduce the size of the finite elements for final verification calculations (if the hardware is sufficiently capable). By reducing the element size, we increase the number of segments into which the beam is divided, since in the cross section, the beam is always modeled by one beam element. One of the goals of current research is to present an applicable methodology for the UNECE R29 simulation. Despite the regulatory-determined energy value of 55 kJ according to R29, the question of the influence of energy growth on the front part deformations is relevant. For this purpose, an additional FEA calculation with an energy value of 100 kJ was performed, which caused an increase in angular velocity to 3.16 rad/s according to Equation (11). Since larger deformations were expected, the mesh density of the front overhang (Figure 7a) was increased (the size of the FE was reduced to 50 mm) in order to obtain more accurate results. Thus, the beam model has increased the number of finite elements from 2281 to 3069 and the number of nodes from 4150 to 5726 accordingly. The maximum deformations (Figure 7b) were 870.2 mm (+50.8%), and the mounting points (Figure 6) received significant changes: A and B obtained 2.8 and 146.8 mm, respectively. The relative A and B deformations of some other points were higher by more than 30% compared with Table 1: #1--581.4 mm and 437.4 mm; #4--650.2 mm and 506.2 mm; #7--662.1 mm and 518.1 mm. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{6}{c}{**Relative Deformation between Control and Mounting Points Along Y-Axis, mm**} \\ \hline
**Level** & \multicolumn{2}{c}{**Hands**} & \multicolumn{2}{c}{**Knees**} & \multicolumn{2}{c}{**Feet**} \\ \hline
**Points** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8 * & **9** \\ \hline A & 382.9 & 154.5 & 511.4 & 412.2 & 154.5 & 557.1 & 481.1 & 107.5 & 159.8 \\ \hline B & 346.2 & 117.8 & 474.7 & 375.5 & 117.8 & 520.4 & 444.4 & 70.8 & 123.1 \\ \hline \hline \end{tabular}  
* point #8 corresponds to the location of the pedal unit.  
\end{table} 
Table 1: The effect of a frontal impact on the change of the residual space of the driver at different levels. Overall, the authors' opinions are as follows:  
* R29 deforms the front part well, but without affecting the rest of the bus sections (passengers do not feel the acceleration impact enough), and NCAP is more focused on assessing accelerations at control points, as in the case of R80 (passengers feel the impact enough on the seats), but the front parts are far from deformations seen with R29. * The model case of the frontal collision simulation is to be performed both in the R29 and NCAP tests--their combination allows us to determine bus body complex safety. In addition, it is worth taking into account separate rules for the city buses, in which the maximum permissible speed should be limited to 50 km/h and the obstacle with a rigid wall with the height reduced to only 1 m.
* In fact, it is worth conducting both experiments to comprehensively evaluate the safety of the bus. This especially applies to city buses, which have an unusual speed limit of 50 km/h. One of the ideas for testing the frontal collision of city buses is to use a 1m high NCAP rigid wall (this will be consistent with the impactor parameters according to R29) and limit the speed to 50 km/h. This will definitely be a topic for future research.