Mechanics
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ISSN 1734-8927
e-ISSN: 2300-7060
Issue Date
2006
Volume
Vol. 25
Number
No. 3
Description
Journal Volume
Mechanics
Vol. 25 (2006)
Projects
Pages
Articles
Determination of the aerodynamic lift for a radial rotor passage model using the pressure distribution method
(Wydawnictwa AGH, 2006) Baca, Stanisław; Fortuna, Stanisław
The article presents an attempt to solve the problem of aerodynamic lift in a radial grid of blades experimentally. The blade passage model was tested in a negative pressure wind tunnel and a possitive gauge pressure wind tunnel. The lift coefficient in the function of the angle of attack on the inlet blade edge was determined. This study contributes new data to the research on the aerodynamic lift and drag force of blades and radial grids.
Analyses of sound isolating attributes for recycling materials
(Wydawnictwa AGH, 2006) Badida, Miroslav; Zvirinský, Vladimír; Lumnitzer, Ervin
All acoustical materials and structures perform better at some freguencies than others. For this reason, a frequency analysis of the noise to be controlled is almost always required for reduction occupational or environmental noise. Recycled rubber structures made from road tyre and car seat can absorb noise thanks porous structure. For mapping needed acoustical descriptors we designed apparatus for measuring the acoustical absorption (?n), acoustical reflection (Ro), acoustical transmitted (Rp) and acoustical isolation (Dnf) coefficients for normally incident sound which define acoustical materials at once. Realized prototype of apparatus based on the impedance tube and standard featuring of a sound level meter was registered as Industry Design No 3679 from 9.10.2003 by Bureau of Slovakia Industrial Property. This paper deal of frequencies analysis basic occupational acoustic characteristics of recycled porous rubber structures.
Vibration energy flow in ribbed plates
(Wydawnictwa AGH, 2006) Cieślik, Jacek; Bochniak, Wojciech
The paper presents obtained from literature review formulations on structural intensity calculations. The formulas involve the loads (forces and moments) and strains (linear and angular) which enabled the evaluation of structural surface intensity for beams, shells and plates considered here as simple constructional elements. The numerical method of intensity evaluation was based on complex modal analysis with use of finite element method. There are presented results of the calculations which lead to the assessment of distribution of structural intensity vectors on the surface of simply supported, ribbed rectangular steel plate. The model included the source of vibrations (force excitation) and sink of energy (damper) with known position of application. The changes of finite elements grid density enabled detailed analysis of total vibration energy flow in analysed plate. Such solved problem was intended to show the usability of structure surface intensity method in diagnostics of joints in mechanical constructions.
Experimental study of acoustic properties of interior facing panels
(Wydawnictwa AGH, 2006) Kamisiński, Tadeusz
This paper presents a study on the sound absorption reverberation coefficient of Fermacell RIGIPS gypsum facing panels. The facing panels showed a high value of the sound absorption coefficient for frequencies below 200 Hz. A study was also undertaken on methods for reducing the multiple echo. The dependence of the multiple echo decay on the angle of deviation from parallel arrangement of walls was determined. Also studied was the effect of the room's acoustic absorptivity on the identifiability of the multiple echo. The study has demonstrated usefulness of commonly available wall facing in the design of acoustic system capable of significantly reducing most frequent acoustic defects of rooms.
Stress analysis in slotted springs
(Wydawnictwa AGH, 2006) Michalczyk, Krzysztof
In this paper the modern construction of slotted springs was presented. It was proven that maximal stresses in such springs under load have higher values than the stresses calculated with previous method. The new model of phenomena and calculating method based on it was proposed. The new method gives results closer to FEM analysis than the previous.