Ústav automobilního a dopravního inženýrství

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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.
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.
Small Cogeneration Unit with Heat and Electricity Storage
(MDPI, 2021-04-09) Štětina, Josef; Březina, Michal; Böhm, Michael
A micro cogeneration unit based on a three-cylinder internal combustion engine, Skoda MPI 1.0 L compressed natural gas (CNG), with an output of 25 kW at 3000 RPM is proposed in this paper. It is a relatively simple engine, which is already adopted by the manufacturer to operate on CNG. The engine life and design correspond to the original purpose of use in the vehicle. A detailed dynamic model was created in the GT-SUITE environment and implemented into an energy balance model that includes its internal combustion engine, heat exchangers, generator, battery storage, and water storage tank. The 1D internal combustion engine model provides us with information on engine start-up time, actual effective power, friction power, and the amount of heat going to the cooling system and exhaust pipe. The catalytic converter was removed from the exhaust pipe, and the engine was always operating at full load; thus, engine power control is not considered. An energy storage system for an island operation of the entire power unit for a large, detached house was designed to withstand accumulated energy for a few days in the case of a breakout. To reach a low initial system cost, the possible implementation of worn-out battery packs toward emission reduction in terms of the second life of the battery is proposed. The energy and emission balance are carried out, and the service life of the engine is also discussed.
Optimal design of structure in rheological models: an automotive application to dampers with high viscosity silicone fluids
(JVE International, 2017-10-09) Píštěk, Václav; Klimeš, Lubomír; Mauder, Tomáš; Kučera, Pavel
Dynamic torsional vibration dampers are for a long time inherent integral components of internal combustion engines. One of the most common types of the dynamic dampers is a silicone damper. It has been, for many years, perceived as an exclusively viscous damper, thus it has been constructed and designed according to this perception. When compared to other types of dynamic dampers of the similar size with flexible components used for their construction, the standard iscous damper has a lower damping effect. Moreover, this damper type has been a significantly cheaper and simpler solution. Current silicone oils with high nominal viscosity, having not only the expected damping properties, but also significant elastic characteristics under alternate shear stress, enable construction of dynamic dampers with a higher damping effect than a viscous damper. Frequency and temperature dependent complicated rheological properties of high viscosity silicone fluids can only be identified experimentally using a suitable dynamic viscometer. However, the measured frequency dependencies of both components of the complex shear modulus are only defined for harmonic loading while internal combustion engine load is periodic and contains several tens harmonics. The key to the solution is therefore to find suitable multiparameter rheological models comprised of linear elastic and damping elements that would approximate in the specified frequency range both components of the complex shear modulus. Such a complicated task can be solved using efficient optimization algorithms. This article focuses on the mathematical description of convolute rheological properties of high viscosity silicone liquids and also contains an example of the application of created rheological models in the complex dynamic model of a V10 diesel engine. A computational tool for the determination of stiffness and damping coefficients of the multi-parameter rheological model was created and solved in the optimization software GAMS by means of the CONOPT solver. The possibility of these modern technologies is shown by the comparison of computation models and experimentally set torsional vibration spectres with standard viscous damper and damper utilizing a high viscosity silicone oil.
Ensuring Reliable and Safe Operation of Trunk Diesel Engines of Marine Transport Vessels
(MDPI, 2022-09-26) Sagin, Sergii; Madey, Volodymyr; Sagin, Arsenii; Stoliaryk, Tymur; Fomin, Oleksij; Kučera, Pavel
In this study, a method for ensuring reliable and safe operation of marine trunk diesel engines is considered. The research was carried out on 5L23/30 MAN-B&W diesel engines of a Bulk Carrier class vessel. The objective of the study was to determine the effect of the structural characteristics of the oil layer (wetting angle and thickness) on the operational parameters of a marine diesel engine (compression pressure, concentration of nitrogen oxides in exhaust gases and temperature of exhaust gases after the cylinder) and performance characteristics of the oil (base number, wear and contaminant elements). It has been established that an increase in the degree of the contact angles of wetting and in the thickness of the oil layer improves the heat and power and environmental performance of a diesel engine. At the same time, the decrease in compression pressure in the cylinder slows down, the temperature of gases after the cylinder decreases, and the emission of nitrogen oxides with exhaust gases decreases. Also, it was found that wear of diesel parts and oil oxidation are reduced. The study confirms the possibility of improving the reliable and safe operation of trunk-type diesel engines of maritime vessels by effective control of variables relating to the characteristics of engine oil.

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