Ústav automobilního a dopravního inženýrství

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Measuring Device for More Precise Mistuning Identification of Integrated Bladed Discs
(MDPI, 2025-05-07) Kučera, Ondřej; Píštěk, Václav; Fomin, Oleksij; Kučera, Pavel; Sagin, Sergii
In integrated turbine wheel designs, small deviations, known as mistuning, often occur in the modal properties of individual blades due to manufacturing tolerances and material inhomogeneity. During operation, this mistuning can cause some rotor blades to be subjected to significantly higher loads than predicted for an ideal rotor. The degree of rotor mistuning can only be determined using methods of experimental modal analysis. However, the manual use of the modal hammer cannot ensure precise repeatability of the force impulse’s location and timing, leading to inaccuracies. This article introduces a mechanism that replaces manual modal hammer operations, guaranteeing consistent impact location and timing while eliminating double strikes. The device was verified on bladed discs of various sizes, and its usability is demonstrated in this article on a turbine wheel of a marine engine turbocharger. The developed mechanism automates modal hammer strikes, ensuring precisely repeatable force courses and positioning for each impact. This automation reduces the measurement time and significantly improves the accuracy. The results of this research showed that even with careful manual operation of the modal hammer by an experienced operator, statistically significant differences arise in the repeated measurements of a bladed disc mistuning, whereas with the use of the presented measuring device, the results of the repeated measurements are practically identical.
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.

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