Technical system for condition monitoring and failure diagnostics of gear driver with roller bearings was tested in situ. The experimental measurement data of rotors shaft vibration displacements were introduced into physical model of gear teeth meshing dynamics. The modelling and simulation of teeth failures in gear driver with roller bearings was performed by finite element method. The experimental and simulation results were used in identification and elimination of sources of gear teeth damages and bearings failures.
The aim of this study was to design and test an adjustable hydro-pneumatic damper for cab suspension. The goal was to make a simple and cheap solution for a damper, which is intended to be placed between the hydraulic cylinder and accumulator. Damping behaviour of different terrain types had to be taken into consideration. Terrain type varies from field to road driving and damping should react rapidly to varying conditions.
In this study, the semi-active damper has been built with a hydraulic direct acting cartridge type 2/2-way proportional flow control valve. Flow-pressure curves and dynamic tests were carried out in the laboratory. The dynamic test with forced vibration focused on stability in damping frequencies and step response between different states. Also, total damping force was measured in different damping states and the proportional valve’s precise step responses and stability were investigated in a closed hydraulic system.
As a result, this research gave a lot of new information about the proportional valve’s applicability to work as a semi-active damper and information about damping behaviour. Research showed that a proportional valve can work in a cab suspension damper as well as a multi-fixed orifice damper. Bi-directional flow in the proportional valve was found to remain stable in cab suspension working conditions. The proportional valve also has the ability to work as a continuous state damper, which could lead to better damping results with the appropriate control system.
The research project “Railcab” designs a shuttle-based transportation system, which combines innovative mechatronic technologies with existing railway tracks. The traction and braking forces are generated by a linear electromagnetic drive while the tracking and guidance is performed using classical wheel/rail technology. By adopting different mechatronic modules, a modular structuring of the overall system, the driving safety, vehicle dynamics and the travelling comfort can be increased.
In the present paper, we concentrate on the development of the active tracking module which reduces the sensitivity of the system behaviour with respect to the friction in the wheel/rail contact. Basic ideas of the tracking module are self-optimizing active tracking, camber adjustment, and mechanical locking device. Based on a-priori identified risks, like e.g. strong cross-wind, frosted rails and crossing of switches, the safety concepts are described in detail together with the methodology that was used in the design process.
The aim of the paper is to present a procedure for generating service loading for fatigue tests of materials and structures. The generated loading characterizes desired functions of probability distribution and autocorrelation. The proposed numerical procedure uses MATLAB toolboxes and consists of three steps: (a) generation of a sequence of real numbers with the desired autocorrelation function and with any probability distribution function; (b) generation of loading history with the desired probability distribution function; (c) rearrangement of loading history (mentioned in item b) based on a sequence of real numbers with the desired correlation (mentioned in item a).
In this paper, the authors present surface roughness profile assessment using continuous wavelet transform (CWT). Roughness profiles after turning and rough and finish belt grinding of hardened (62HRC) AISI 52100 steel are analyzed. Both Morlet and “Mexican hat” analyzing wavelets are used for the assessment of extrema and frequency distribution. The results of the CWT as a function of profile and momentary wavelet length are presented. It is concluded that CWT can be useful for the analysis of the roughness profiles generated by cutting and abrasive machining processes.
The examination of a smart beam is presented in the paper. Experimental investigations were carried out for flexible beam with one fixed end and free opposite end. Piezoelectric strips were glued on both sides of the beam. One strip works as a sensor, and the second one as an actuator. It is a single input and single output system. The study focuses on the analysis of natural frequencies and modes of the beam in the relation to the position of the piezo-elements. The natural frequencies, mode shapes, generated control forces, and levels of the measured signals are considered and calculated as a functions of the piezo-element locations. We have found correlations between mode shapes, changes of natural frequencies, control forces and measured signals for the lowest four modes. In this way, we can find the optimal localization of the distributed sensors and actuator on the mechanical structure directly by the using of the finite elements method (FEM).
The paper presents research on dynamics, modeling and the results of experimental tests of the rotor system rotating in gas lubricated bearing with a floating bush. The dependence of rotor vibration intensity on the waviness of bearing elements was tested and simulated. It was confirmed experimentally that the amplitude of rotor vibration in gas lubricated bearing with double gas film is basically lower than the one with single gas film. The kinetic orbits of the rotor shaft vibration displacements are presented. Dynamic and mathematical models constructed enable to design bearings that distinct optimal according to the minimal vibration intensity.
The article presents the research on the reduction of noise and vibrations carried out using screen theory and its implementation in practice. Acoustic screens are divided according to their application and structures. The article deals with the application of screens in practice, gives their theoretical evaluation and analyses influences of their structure and materials. The evaluation of positive and negative acoustic properties of the screens is given. The conclusion is that screen acoustic properties may be improved by including new elements into design of screens, thus increasing their efficiency in reducing noise effect. Theoretical calculations are performed, and the obtained results are analyzed. In conclusion, it is stated that cylindrical, semi-cylindrical or conical elements have to be applied in the screens.
This paper presents problems of technological equipment vibromonitoring. Mechatronic systems designed for monitoring and control of complex rotary machines can be implemented effectively only when alert or critical levels of the monitored parameters are well known and sources of parameter deviations can be determined. Vibrodiagnostics is a powerful tool, which can be used for diagnosing of machine defects. However, in the case of complex rotary machines, it is very complicated to trace all sources of vibrations (e.g. internal defects). Therefore, attempts of vibration modeling are made aimed at evaluating the influence of various parameters on vibroactivity of a certain machine.
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Archive of Mechanical Engineering is an international journal publishing works of wide significance, originality and relevance in most branches of mechanical engineering. The journal is peer-reviewed and is published both in electronic and printed form. Archive of Mechanical Engineering publishes original papers which have not been previously published in other journal, and are not being prepared for publication elsewhere. The publisher will not be held legally responsible should there be any claims for compensation. The journal accepts papers in English.
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