Ústav automobilního a dopravního inženýrství

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Multi-Body Model of Agricultural Tractor for Vibration Transmission Investigation
(MDPI, 2024-09-19) Rekem, Jakub; Janečková, Radka; Otipka, Václav; Prokop, Aleš; Řehák, Kamil; Žlábek, Pavel
This 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.
Influence of Sine-Shaped Profile Deviations on Static Transmission Error
(Brno University of Technology, 2024-05-16) Rackovský, Daniel Milan; Czakó, Alexander
Transmission 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.
Influence of simplifying the geometry of the FE model of the vehicle forntal full barrier crash test
(Brno University of Technology, 2024-05-16) Jančář, Radek; Dlugoš, Jozef; Fridrichová, Kateřina
The deformation of the vehicle as a result of the accident serves as the input for determining the impact speed for the purposes of the expert report. One possibility of calculating the impact speed is by means of a verified finite element analysis (FEA) of the vehicle impact. However, to develop such a sufficiently accurate finite element (FE) model requires a significant financial and time investment. Such a model contains a number of key simplifications that are difficult to detect without prior experience. Fortunately, there are at least a few freely available detailed FE vehicle models that have been experimentally verified. On these it is possible to investigate the effect of different modelling methods on observed parameters such as overall deformation. This paper is specifically concerned with the sensitivity of FEA results to different levels of vehicle geometry modelling. A Chevrolet Silverado 1500, model year 2014, is used as a detailed FE vehicle model.
The research of the influence of viscous interaction between wagon and container on the dynamic load during transportation by rail ferry
(JVE International, 2020-05-07) Lovska, Alyona; Fomin, Oleksij; Píštěk, Václav; Kučera, Pavel
This paper proposes the improved scheme of interaction of containers with the load-bearing structure of the wagon when transporting by rail ferry. In order to ensure the stability of the container balance in the event of fluctuations in the railway ferry, it is proposed to attach special structures to the support structure of the wagons. To reduce the dynamic loading of containers, a material with damping properties is installed on the internal surfaces of the superstructures. Mathematical modelling was performed to substantiate the proposed technical solution. It was found that the total amount of acceleration that acts on the container is 3.47 m/s2 (0.35 g), and on the load-bearing structure of the wagon 2.47 m/s2 (0.25 g), which is 38 % and 23 % less, respectively, for the acceleration values in the typical scheme of their interaction. The conducted research will contribute to improving the efficiency of combined transport through the international transport corridors.
Methodological Approach in the Simulation of the Robustness Boundaries of Tribosystems under the Conditions of Boundary Lubrication
(MDPI, 2023-01-04) Al-Quraan, Tareq M. A.; Alfaqs, Fadi; Alrefo, Ibrahim F. S.; Vojtov, Viktor; Voitov, Anton; Kravtsov, Andrey; Miroshnyk, Oleksandr; Kondratiev, Andrii; Kučera, Pavel; Píštěk, Václav
In the presented work, a methodical approach was developed for determining rational operation modes of tribosystems, taking into account their design. This approach makes it possible in the designing stage, according to the predicted operating modes, to calculate the limits and margins of stable work in operation. The definition of the robustness of the tribosystem and the criteria for assessing the robustness are formulated based on the theory of stability of technical systems. It is shown that such a methodical approach allows for determining the modes of the rational operation of the designed structures without damaging the friction surfaces. Experimental studies have proven that not all designs of tribosystems lose stability due to the appearance of friction surface burrs. There are designs where the loss of stability occurs upon the appearance of accelerated wear. The developed criteria take into account two options for the loss of stability. An experimental verification of the modes of loss of stability of tribosystems was performed by the appearance of a burr or the beginning of accelerated wear with the calculated values of the robustness criteria. The obtained results allow us to conclude that the modeling error is within 8.3–18.7%, which is a satisfactory result in the study of friction and wear processes. Robustness criteria is based on the coefficient of friction RRf and wear rate RRI, and must be used when designing new constructions of tribosystems. Theoretical calculations of such criteria and the dependence of their change on changing the predicted operating modes will allow for justifying rational operating modes within their stability.

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