Frolov A. Improvement of the method of determining the adhesion utilized of tires at dual wheels vehicle with the surface of the road pavement

A. Frolov. Improvement of the method of determining the adhesion utilized of tires at dual wheels vehicle with the surface of the road pavement. – Qualifying scientific work on the rights of the manuscript. Dissertation for obtaining the scientific degree of candidate of technical sciences (doctor of philosophy) in the specialty 274 – Automobile transport. – Kharkiv National Automobile and Highway University Ministry of Education and Science of Ukraine; Kharkiv National Automobile and Highway University Ministry of Education and Science of Ukraine, 2023. The dissertation is devoted to the improvement of the method of determining the adhesion utilized of the tires at dual wheels vehicle with the road surface, the study of the influence of the weight-geometric parameters of the wheeled vehicle on the value of the adhesion utilized of the single and dual tire of the vehicle wheels, the experimental study of the braking efficiency of the wheeled vehicle due to only the wheels of one of its axles, the development of the approach to determining the deceleration of the wheeled vehicle due to the method of determining the adhesion utilized of the tires at dual vehicle wheels. The relevance of the dissertation work is determined by the need to solve the scientific and practical task of improving the method of determining the adhesion utilized of tires at dual vehicle wheels with the road surface by obtaining new interconnections between the rigidity parameters of pneumatic tires of wheeled vehicle wheels and the adhesion utilized that realizes between the tire and the road surface. In Ukraine, as well as most other foreign countries of the world, all wheeled vehicles must meet the requirements of the UN/ECE international standard regarding the braking of vehicles categories M2, M3, N2 , N 3 and O, therefore the improvement and development of new methods that will improve the effectiveness of vehicle braking control at the stage of its design or experimental bringing to serial production, is an actual task. The lack of effective methods for evaluating the braking efficiency of wheeled vehicles at the stage of their design forces domestic automobile plants to use brake systems and components of foreign automobile components and systems manufacturers in the designs of domestic vehicle, which leads to an aggravation in the competitiveness of ukrainian vehicle on the world market. Based on the conducted theoretical and experimental research, a new approach is proposed, which allows to improve the method of determining the adhesion utilized of the dual wheels vehicle tires with the road surface and to improve the performance indicators of the vehicle at the stage of its design. During the conducted research, it was theoretically proven and experimentally confirmed that the value the adhesion utilized of the tire of single or dual wheels of the vehicle, together with the coordinates of the gravity center position of the vehicle relative to its axles, affect on deceleration value of the wheeled vehicle. This gives reason to conclude that their impact must be taken into account not only during the design of the vehicle, but also during the study of the circumstances of the occurrence of traffic incidents. Based on the analysis of the theoretical and experimental research results, for the further improvement of the method of determining the adhesion utilized of the tires of a dual vehicle wheels, an approach for determining the adhesion utilized by rigidity and deformation properties of pneumatic tires is proposed, which differs from the known one in that it is based on the change in the torsional rigidity of the pneumatic tire and the twisting angle of the tire relative to the road surface. In the work, a mathematical description of the improved method of determining the adhesion utilized, an approach for determining the torsional stiffness of single, dual, triple and more tires of wheels is performed. Approaches for determining the deceleration value of wheeled vehicles with more than two axles and which take into account the peculiarities of the influence not only the adhesion utilized, but coordinates of the gravity center position also, on deceleration value of the wheeled vehicle are proposed. Modeling of the working process of the tires interaction of a wheeled vehicle wheels with the road surface showed that the adhesion utilized does not change proportionally to the load on the dual tires of the wheeled vehicle wheels. It should also be noted that the adhesion utilized of dual and single tires of the vehicle wheels varies by no more than 13% - 20% under the same loading conditions on such wheels.