Assessment of the stability of a road train moving along a curved trajectory.
Students Name: Rudenko Dmytro
Qualification Level: magister
Speciality: Motor Vehicle Transport
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: part
Academic Year: 2025-2026 н.р.
Language of Defence: ukrainian
Abstract: The master’s thesis presents a comprehensive study of the stability of a road train based on the analysis of forces acting on the vehicle, using the principle of superposition. The aim of the work is to improve the accuracy of stability assessment and predict the behavior of the road train under various driving conditions. The work provides an overview of the theoretical foundations of road train stability, the characteristics of the action of force factors, as well as methods for modeling the dynamics of automotive transport systems. A mathematical model has been developed that takes into account the interaction between the tractor and trailer/semitrailer, the impact of external forces, and the change in load dynamics. The model is based on the principle of superposition of forces, which allows the separate consideration of the main force components and the evaluation of their combined effect on longitudinal, lateral, and directional stability. The longitudinal stability of a road train characterizes its ability to maintain straight-line motion without jackknifing during braking or acceleration. It depends on the distribution of braking forces between the tractor and the semi-trailer, the tire-road friction coefficient, and the condition of the coupling device. Lateral stability determines the road train’s resistance to tipping or lateral displacement when cornering. The main factors are the height of the center of mass, driving speed, turning radius, suspension stiffness, and the road’s cross slope. Directional stability is the road train’s ability to maintain a set driving direction without significant trajectory fluctuations. Violations of directional stability may appear as semi-trailer snake-like movements, especially at high speeds or in crosswinds....Numerous experiments and simulations were conducted for different road conditions, speed regimes, loading options, and maneuvers. The results obtained allowed identifying critical conditions that most reduce stability, as well as assessing the sensitivity of the road train to changes in parameters. Based on the analysis, engineering solutions were proposed to improve stability, including optimization of design features, traction parameters, and the use of active safety systems. The results of the work can be used in the design of road trains, improvement of control systems, development of recommendations to enhance traffic safety, and training of automotive industry specialists. The object of study: the movement process of the road train and its dynamic behavior under the influence of external and internal forces.