Mechanics and Control
Loading...
ISSN 2083-6759
e-ISSN: 2300-7079
Issue Date
2013
Volume
Vol. 32
Number
No. 3
Description
Journal Volume
Mechanics and Control
Vol. 32 (2013)
Projects
Pages
Articles
Thermoanemometrical study of flow structure through a centrifugal fan
(2013) Fortuna, Stanisław; Górski, Jan; Siwek, Tomasz
Recognition of the spatial kinematics of the flow domain and its relation to the fan impeller geometry has a key influence on the machine design and better performance parameters. In this work some experimental results are presented of the measurements of the absolute velocity, its components and turbulence of the air flow through the radial fan rotor operating in various configurations. As the main measuring tool a three-axial hot-wire anemometer (CTA) probe has been used. The anemometer cooperates with a specialized software prepared by the authors for the spatial analysis of the flow field considered. In particular, the distribution of the circumferential velocity components behind the impeller rim has been examined, which affects directly the fan efficiency. As a result of the flow analysis behind the rotor rim a relationship has been established between the degree of turbulence and the machine efficiency. On the basis of the changes in the averaged-in-time velocity field behind the rim, the outflow of air from the blade passage has been evaluated.
Modelling of the seat suspension system for the vibration control system
(2013) Koszewnik, Andrzej Piotr; Gosiewski, Zdzisław
In this paper, a model of the passive seat suspension system is designed. To verify the model the excitation signals are modelled by using generator embedded to Simulink software. Additionally, the excitation signal is filtered with the use of the Butterworth filters. The vibroisolation properties of the system are calculated on the basis of the ratio transmissibility of the vibration. The investigations proved that the designed system is correctly modelled and the system damps the vibration speciously in the most dangerous frequency range up to 20 Hz.
Low frequency identification of critical states of transmission tower structures
(2013) Szopa, Krystian; Iwaniec, Marek; Gołaś, Andrzej
Transmission towers are vital parts of the overhead power line infrastructures. Any damage to these supporting structures may result in decreased load-bearing capacity and, in consequence, their collapse. Failures of transmission towers are much more severe than power failures, as they not only cause interruption to the energy supply but can also result in considerable costs of infrastructure repairs and damage. Therefore, supporting structures of overhead power lines should be subjected to structural health monitoring. This paper presents a comprehensive database containing natural frequencies and strain energies of all elements for various (simulated) damage states. On the basis of structure modal parameters, by finding the correlation between natural frequencies of damaged structure stored in the created database and natural frequencies of the structure of interest, state of the test structure can be identified. In order to verify this method, a numerical experiment was carried out. Observing the strain energy variation as compared to the undamaged state makes it possible to localize the damage and assess its importance for the further structure exploitation.
Simulation study of the non-collocated control of a cantilever beam
(2013) Tůma, Jiří; Mahdal, Miroslav; Šuránek, Pavel
This article deals with the simulation of the active vibration control of a cantilever beam. For these purposes, a lumped parameter model has been developed and the simplest controller has been designed to ensure the structural stability of the control loop. The controller is of a proportional velocity feedback type. The control loop can also be stable in the case of a very small inherent damping of the cantilever beam. The lumped-parameter model is based on the Euler-Bernoulli beam theory. The developed tools can be used to simulate the collocated and non-collocated active vibration control. Since this article is intended to study the behaviour of a non-collocated control system of the transducer is sensing the vibration of the free end of the beam, while the actuator force acts near the fixed end.
Sound absorbing materials from recycled rubber products
(2013) Turkiewicz, Jadwiga; Sikora, Jan
This paper concerns the results of comparative research into the acoustical properties of rubber granulates derived from the recycling of conveyor belts production waste. In the process of recycling it is possible to obtain pure granulated rubber and forms contaminated with cotton fibres with a predominance of rubber grains or of cotton fabric. Rubber granulate in the contaminated form is characterized by sound-absorbing properties similar to those of the average-quality mineral wool and other fibrous materials. It can be used as the core of sound-absorbing panels in anti-noise protections. The research results can be used both in the design of acoustical protection as well as in the course of the recycling process of other waste products for obtaining materials with sound absorbing properties.