Scientific Journal of Silesian University of Technology. Series Transport

6

Authors: Alžbeta SAPIETOVÁ, Pavol NOVÁK, Peter ŠULKA, Milan SAPIETA, Lenka JAKUBOVIČOVÁ

Durability calculations of bearings take in account the distribution of forces on rollers. Calculation of these forces in flexibly supported rings is the aim of the paper. We use simplified finite element (FE) models of bearings, which are integrated into the external geometry. This approach can consider the stiffness of the surrounding structure as well as the clearance of the bearing rings, the misalignment of bearings, shaft deflections, and the forces of crowning rollers. The presented results show an influence of the initial radial interference of the outer ring with housing on the distribution of forces in bearing rollers. As the radial stiffness of the housing is close to the stiffness of the outer ring interference, this causes considerable deformation of the housing. The presented approach is also able to calculate the distribution of contact pressures over any rolling element.

9

Authors: Feng CHEN, Katarzyna TUROŃ, Marcin KŁOS, Piotr CZECH, Wiesław PAMUŁA, Grzegorz SIERPIŃSKI

The article is focused on sustainable transport development solutions in cities, such as bike-sharing systems. We discuss the main principles of bike-sharing, its generations, types, and benefits to system users and entire urban transport systems. The aim of the article is to present a comparison of bikesharing systems found in Polish and Chinese cities. The authors also consider new market practices, which can be implemented when introducing or improving current bike-sharing systems.

10

Authors: Dmytro FEDIN, Boris VINOGRADOV

In tumbling mill drives, increased dynamic loads may occur in open gearing, which may cause an increase in the vibratory activity of the drive assembly and in dynamic loads in the mechanical drive system as a whole. Today, no adequate method is available for calculating the dynamic loads in the open gearing of tumbling mills. The article is devoted to the development of a method for dynamic load calculation, which takes into account the parameters of the drive system. The authors have proposed a mathematical model and a technique that allows for the identification of dynamic loads from experimental data and controlling the vibratory activity of the mechanical drive system of a tumbling mill at the design stage.

10

Authors: Silvia MEDVECKÁ-BEŇOVÁ

The paper examines the design and generation of gear drives with non-circular gears. Gearings with a changing transmission gear ratio are used for the purposes of practical experimentation, even though “standard” gearings with a constant transmission gear ratio are used more often. In this paper, the author presents the design for the shape of a pitch outline for a specific requirement, that is, continuous change in gear ratio during one rotation. The gearing is designed such that the pitch curve is composed of an ellipse. The article also presents some kinematic properties of the designed non-circular gearing.

10

Authors: Serge NEMCHINOV, Alexander KHRISTENKO

The article explores the stress-strain state of the pneumatic flexible shaft coupling of the tumbling mill drive using a software of finite element analysis. The study has revealed that the stress-strain state of the pneumatic flexible shaft coupling is characterized by an uneven general and local distribution of stresses. Areas of maximum stress and strain in the pneumatic flexible shaft coupling have been defined. The study allowed for changing the geometry and reducing the mass of the disc of the pneumatic flexible shaft coupling with a slight change in stresses and strains. The results of the study can be applied to the design of pneumatic flexible shaft couplings and serve as a basis for further research.

11

Authors: Robert GREGA, Jozef KRAJŇÁK, Marek MORAVIČ

The field of reducing torsional vibration of mechanical systems has seen the emergence of new flexible coupling designs. Our attention is focused on flexible pneumatic couplings. The flexible member of this coupling design is a pneumatic bag. The typical basic feature of such couplings is that the pneumatic bag allows for a change in air pressure. In the course of developing pneumatic couplings, we have experimented with the use of technical gases other than air for filling pneumatic bags. The aim has been to verify the impact of pneumatic couplings filled with other technical gases on the magnitude of torsional vibration in the mechanical system. For verification itself, two different gases have been used: helium, whose density is lower than air density, and propane butane, whose density is higher than air density. Experimental verification was performed under laboratory conditions on a mechanical system where torsion vibration was produced by a piston compressor.

11

Authors: Matej URBANSKÝ

The optimal tuning of mechanical systems in terms of torsional vibration magnitude is a very important function in flexible shaft couplings. Therefore, a flexible coupling with suitable dynamic properties, particularly dynamic torsional stiffness, has to be carefully chosen for each specific application. The current trend in the field of flexible shaft couplings, and the most noticeable in the automotive industry, is the development and utilization of highly flexible couplings, which means flexible couplings with a very low value of relative torsional stiffness. The aim of this article is to introduce a new type of flexible shaft coupling: a piston pneumatic flexible shaft coupling. This coupling was developed to improve the properties of pneumatic flexible couplings, especially the maximum angle of twist, in order to create a highly flexible pneumatic coupling. For illustration purposes, the piston pneumatic coupling is compared with the tangential pneumatic flexible shaft coupling of Type 3-1/110- T-C in terms of high flexibility characteristics, whereby the characteristic dimensions of both couplings are the same. Given that the piston pneumatic coupling has not been manufactured to date, only a computational model of this coupling was used. The results show that the design of the piston pneumatic flexible shaft coupling combines the advantages of a highly flexible and pneumatic shaft coupling.

13

Authors: Olha SAKNO, Dmitry MOYSYA, Tatiana KOLESNIKOVA

In this paper, we consider the mobility and stability of a model of a tractor-lorry-trailer combination, consisting of a two-axle tractor and a single-axle semi-trailer, and its possible stationary states with fixed steering. A feature of this research is the study of a non-linear mathematical model of a two-link tractorlorry-trailer combination. The set of steady-state conditions for the movement of the tractor-lorry-trailer combination model is determined on the basis of the developed mathematical model; it provides the necessary mobility for the passage of the circular overall traffic lane. The range of stable steady-state conditions of the road train is limited and the character of the loss of stability in the direct motion of the road train (divergent, flutter) is checked. The phase portraits of the system are constructed at different speeds, which allow us to estimate the range of attraction for direct motion. Stability issues are also considered, namely, the influence of the control parameters (θ, v) on stability or instability.

14

Authors: Milan SÁGA, Milan VAŠKO, Zuzana SÁGOVÁ, Marian HANDRIK

The aim of the paper is to present the computationally timeconsuming task of simulating the process of randomly oscillating thin-shell structures to realize an optimal design with limitations in terms of fatigue damage. The most important aim here is to design an effective optimization algorithm and choose an appropriate approach for the evaluation of multiaxial fatigue damage in the context of the random and non-proportional character of stress in the structure when considering the standard finite element model. The authors propose their own optimization algorithm, which is described in the present study and, on the basis of tests, has proven to be suitable for the aforementioned technical problems. The proposition of algorithms for calculating the accumulation of fatigue damage in non-proportional and multiaxial stresses (especially in terms of the application of rainflow analysis by decomposition of the equivalent stress, as determined by the appropriate “fatigue” criterion) is very important in such computational processes. The entire computational process was implemented in MATLAB with the “Discret_Opt_Fat” main control program. The article presents the theoretical basis for the presented complex problem solution, its algorithmization and the technical application.