## 1 Introduction
The following conclusions were obtained:  
* Comparing the experimental data of the MPDB test with the calculation results of the constructed analytical model, the errors of evaluation indexes (i.e., OLC, SD, and PM) are below 15%;
* The greater the stiffness of the 25% area, the less deformation of the vehicle front structure and the intrusion into the passenger compartment. The certification of a bus for compliance with the Regulations can be carried out in two main ways: through natural tests or finite element simulation, if the certification body undermines the reliability of the suggested methodology. It is obvious that due to the multiple cost differences between full-scale tests (the body, which is about 40-50% of the bus price, cannot be restored) and FEA simulations, the fierce market competition stimulates exactly the development of calculation methods equivalent to the natural crash tests. In this part or article, scientific works will be examined that are precisely devoted to various simulation methods. It should be noted that in most cases, they are the \"know-how\" of manufacturers, which gives them advantages over competitors, so not all \"secrets\" are described by the authors of the publications below. An interesting approach to the crashworthiness analysis and design of a sandwich composite of an electric bus in a full frontal impact was presented in [10]--the behavior of the bus during a full-frontal collision simulation was thoroughly investigated using LS-DYNA. Analyses of the dynamic responses and structural characteristics of the original and modified bus models in the event of frontal collision with a rigid wall at a speed of 50 km/h were carried out--the average decelerations of the original and modified microbus are 11.2 g and 14.8 g, respectively [10]. The finite element analysis of the frontal impact of a high-decker bus based on ECE Regulation No. 29 was investigated in [11]. The results revealed that the value of kinetic energy in the bus structure with an impact damper is lower than that without an impact damper, especially after 0.02 s. The average energy can be represented as approximately 18,000 J and 21,000 J for the impact damper cases, respectively. The results showed that the deformation amounts of the conventional model and the improved shock absorber models were 47.22 mm and 11.42 mm, respectively [11]. It is reasonable to use the results of bus frontal impact acceleration on the passengers' seats according to Regulation 80 of the United Nations (R80) based on the work [12]--assessment of seat mounting in the frame of a road bus presented for frontal impact. The displayed deceleration should be from 6.5 to 8.5 g. The deformed mode for the numerical model of an impact on a rigid material wall with a speed of 8.89 m/s during 0.5 s. One of the seat screws achieved an impact velocity of 13.89 m/s, but it must be taken into account that this is an extreme condition, the speed that Regulation 80 recommends for dynamic impact tests. The LS-DYNA environment was used in the modeling research [12]. Following the topic of passenger load and acceleration, more details can be found in [13]--injury mechanisms for public bus passengers during frontal, side, and rear impact crash scenarios. Various types of manikin behavior events are observed--mechanisms of head injury (HIC) and neck injury (neck extension, flexion, and compression). The maximum accelerations found during tests were approximately 12 g [13]. The safety of body structure and occupant protection research for medium buses under three kinds of frontal impact forms was investigated in [14]. The authors built a thorough finite element model and used the large deformation finite element analysis method and LS-DYNA dynamic analysis software (Ansys 2023 R1) to simulate impact under the three conditions:  
* Frontal impact with 100% overlap;
* Forty percent offset impact;
* Thirty-degree angular impact;
* And research on vehicle deformation, energy absorption characteristics of acceleration, and their changing regularity [14].