Ústav automobilního a dopravního inženýrství
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- ItemOptimizing ploughing performance: The role of traction-control cylinder pressure on tractor wheel load(Elsevier, 2024-12-01) Čupera, Jiří; Porteš, Petr; Bauer, František; Polcar, Adam; Fajman, Martin; Henzl, JanThis paper examines the impact of pressure change in the Traction-Control cylinder of a six-furrow semi-mounted reversible plough's on the vertical load distribution among the tractor's wheels. The study's findings indicate that increasing the pressure in the Traction-Control cylinder leads to a more balanced vertical load on the rear wheels of the tractor. This balance is achieved by transferring a portion of the plough's weight to the tractor's rear axle. The combined effect of the plough's weight, the vertical force exerted by its support wheel, and the ploughing forces creates a moment that equalizes the load between the in-furrow and on-land wheels. Adjusting the Traction-Control cylinder pressure significantly altered the lateral rear wheel load distribution, shifting the ratio from 60.8/39.2 to 51/49. Additionally, the Traction-Control cylinder's positive impact on fuel consumption and the overall performance of the ploughing set was demonstrated.
- ItemOn the Effectiveness of Optimisation Algorithms for Hydrodynamic Lubrication Problems(MDPI, 2025-05-08) Kocman, František; Novotný, PavelIn many applications, it is necessary to optimise the performance of hydrodynamic (HD) bearings. Many studies have proposed different strategies, but there remains a lack of conclusive research on the suitability of various optimisation methods. This study evaluates the most commonly used algorithms, including the genetic (GA), particle swarm (PSWM), pattern search (PSCH) and surrogate (SURG) algorithms. The effectiveness of each algorithm in finding the global minimum is analysed, with attention to the parameter settings of each algorithm. The algorithms are assessed on HD journal and thrust bearings, using analytical and numerical solutions for friction moment, bearing load-carrying capacity and outlet lubricant flow rate under multiple operating conditions. The results indicate that the PSCH algorithm was the most efficient in all cases, excelling in both finding the global minimum and speed. While the PSWM algorithm also reliably found the global minimum, it exhibited lower speed in the defined problems. In contrast, genetic algorithms and the surrogate algorithm demonstrated significantly lower efficiency in the tested problems. Although the PSCH algorithm proved to be the most efficient, the PSWM algorithm is recommended as the best default choice due to its ease of use and minimal sensitivity to parameter settings.
- ItemMethod for Maintaining Technical Condition of Marine Diesel Engine Bearings(MDPI, 2025-03-25) Sagin, Sergii; Sagin, Arsenii; Zablotskyi, Yurii; Fomin, Oleksij; Píštěk, Václav; Kučera, PavelThe aim of the research was to determine the impact of antifriction coatings on the technical condition of marine diesel engine bearings. Various epilams were used as antifriction coatings, with a thin layer applied to the surfaces of the bearings of the marine diesel engines 12V32/40 MAN-Diesel&Turbo. The thickness of the epilam coating adsorbed on the metal surface was controlled by ellipsometry. It was found that the thickness of the epilam layer on the surfaces of marine diesel engine bearings could reach 11.2 nm to 17.0 nm. The adsorption time required does not exceed 10 min. It was shown that the epilam nanolayer applied to the metal surface led to an increase in the structural characteristics of the oil boundary layer (thickness: from 12.3 µm to 15.2–18.3 µm; contact angles: from 10.2 deg to 15.8–17.4 deg). It was experimentally confirmed that the epilam coating of bearing surfaces significantly reduced their wear. For the 12V32/40 MAN-Diesel&Turbo marine diesel engine, in the case of epilaminating, the wear of the bearing shell surface was reduced by 6.1–27.6%, with the greatest reduction in wear occurring for the stern (most loaded) bearings. This helped to maintain the technical condition of the bearings of marine diesel engines.
- ItemMulti-Body Model of Agricultural Tractor for Vibration Transmission Investigation(MDPI, 2024-09-19) Rekem, Jakub; Janečková, Radka; Otipka, Václav; Prokop, Aleš; Řehák, Kamil; Žlábek, PavelThis article analyses vibration transmission on agricultural tractors with the excitation from the road to the driver’s seat. A multi-body model of agricultural tractors created in Adams is presented. The main parts for the investigation of vibration transmission are the tractor body, where the only suspension elements are tyres, the tractor cabin, spring-dampers suspended at the rear and bushings at the front, and the driver seat with its pneumatic spring. A series of measurements were performed, and the model was validated using vertical acceleration values on the tractor body at four different locations. The FTire model (physical FEM-based model) was chosen to describe the behaviour of tyres. The model was created using measured tyre characteristics. Measured characteristics of spring-dampers and front cabin bushings were also implemented. For comfort investigation, ride simulations on ISO 5008 rough roads were performed. The transmission of vibrations in ride simulations was examined. A modal analysis of the linearised model was performed to confirm assumptions of the contribution of suspension elements to overall vibration levels. Finally, three case studies were conducted to better understand the model’s vibration transmission properties.
- ItemInfluence of Sine-Shaped Profile Deviations on Static Transmission Error(Brno University of Technology, 2024-05-16) Rackovský, Daniel Milan; Czakó, AlexanderTransmission error (TE), a parameter influencing gears vibration and subsequent noise, is a subject addressed in many papers. However, most researchers consider ideal or modified involute while neglecting machining errors. This case study extends the author’s previous work (Czakó et al., 2020) by incorporating tooth profile errors and investigating their impact on static transmission error (STE). Parametric geometry of 2D spur gears, including sine-shaped involute profiles, was generated directly within the Ansys Mechanical environment using APDL (Ansys Parametric Design Language), where all finite element analyses (FEA) were conducted. Various amplitudes corresponding to ISO 1328-1 accuracy grades 1–8, and wavelengths of sine functions modulated onto involutes, were simulated and compared in terms of resulting STE. The results underscore the importance of including profile deviations in models, mainly those common in industry, as they significantly influence transmission error.