Temat: resonance tests - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Structure fatigue crack in the effect of acoustic load : case study
Autorzy:: Wiśniowski, W.
Powiązania:: https://bibliotekanauki.pl/articles/244957.pdf
Data publikacji:: 2014
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: acoustic loads
resonance tests
fatigue cracks
Opis:: The paper presents a method for detection mechanisms and prevention of the fatigue cracks caused by acoustic loads acting on the aircraft elevator structure. During aircraft inspection, the fatigue cracks in elevator rib caps were discovered. The theory emerged, that cracks were caused by acoustic extortion on elevator sheet covering, caused by jet engine exhaust airstream, engine gas flow expanding in convergent nozzle and acting as the source of the strong acoustic load. To prove this theory, investigations were arranged, in which the strains in the elevator sheet skin, between the ribs area, were determined in harmonic excitation. The results, after frequency analysis, showed strong resonance in 270 Hz area. Mode of this resonance caused drumming of covering, resulting in bending of the ribs caps and causing them to fail from fatigue. Changes in elevator design raised the resonance frequency and lowered strains in modified elevator covering. The changes mainly increased sheet-covering stiffness by increase of thickness and lowering the sheet-metal covering mass in selected places, mainly by technological means - metal bonding (gluing) and metal covering chemical milling.
Źródło:: Journal of KONES; 2014, 21, 4; 533-536
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Untypical cases and incorrect results of vibration tests
Autorzy:: Wiśniewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/242412.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: vibration tests
vibration analysis
resonance tests
resonance analysis
modal analysis
Opis:: The vibration analysis is the study of the behaviour and dynamic properties of mechanical structures under actuation by harmonic vibration forces. The aim of resonance tests of the structures is the experimental delimitation of frequencies and the modes of resonance vibrations. vibration analysis, or more precisely experimental vibration analysis, is the field of measuring and analyzing the dynamic response of mechanical structures when excited by a mechanical input. The broadly applied method of research relies on the harmonic actuation of vibrations and the measurement of respective parameters. Examples would include measuring the vibration of an aircraft load bearing structure when it is attached to an electromagnetic force actuator. Current vibration testing systems are composed of actuators set with their control and powering circuits, the vibration measurement transducers (typically accelerometers), an analog-to-digital converter to digitize analog instrumentation signals) and a system host computer to analyze the data and view it. The result of researcher own accumulated experiences and those experiences knownfrom the literature create the possibility for design o f a stochastic frame model describing, what type of resonances are possible to expect in the given or other type of structure. The cases submitted below became perceived and tested in the course of research of several aircraft, glider and helicopter designs in the Resonance Tests Program of the Institute of Aviation
Źródło:: Journal of KONES; 2009, 16, 1; 591-597
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Resonance tests - vibration mode shapes from the wing torsion group
Autorzy:: Wiśniewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/245897.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: transport
aircraft
resonance tests
vibration mode
torsion wing
Opis:: Resonances of the „ wings torsion " mode shapes to a large extent depend on the structural parameters of the wing, and more specifically to the existence or not of fuel tanks at the wings ends, munitions hard points or engines mounted on the wings. In the paper the group of resonances is presented with mode shapes in which the one, two or three node aircraft wing torsion is present. It is shown in the paper, that these vibration mode shapes consist both of fuselage bending or torsion. Resonance frequencies with mode shapes in which one, two or three node wing torsion occurs depend fundamentally on existence of wing hardpoints. If hardpoints are occupied by fuel tanks, these frequencies are varying continuously in wide range. The various interesting from cognitive point of view combinations have place then, including variable frequencies and variable mode shapes as a function of fuel consumption. The aim for the analysis of 3 cases of resonance a wing torsion mode shapes of airplanes and gliders was to investigate the relationships and mechanisms that are taking place and operate between the torsioningl vibration of the wings and bending or torsion vibrations of the fuselage. Recognition of these phenomena should facilitate the researcher to understand and search effectively and explore the resonances of„ wing torsion " mode shapes.
Źródło:: Journal of KONES; 2009, 16, 4; 557-561
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Próby rezonansowe - nowe zastosowania
Resonance tests - a new applications
Autorzy:: Wiśniowski, W.
Powiązania:: https://bibliotekanauki.pl/articles/212609.pdf
Data publikacji:: 2011
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:: aerodynamika
próby rezonansowe
badania dynamicznych właściwości konstrukcji
wyznaczanie współczynników mas
współczynniki sztywności konstrukcji
konstrukcje obciążane w sposób dynamiczny
aerodynamics
resonance tests
new applications
investigation method of dynamic properties and structures
dynamically loaded structures
Opis:: Próby rezonansowe są metodą badania dynamicznych właściwości konstrukcji. Podstawowym ich celem jest wyznaczanie współczynników mas, sztywności i tłumienia występujących w równaniach ruchu konstrukcji. W pracy przedstawiono kilka nowych możliwości wykorzystania prób rezonansowych do identyfikacji oraz interpretacji zjawisk występujących w konstrukcjach obciążanych w sposób dynamiczny.
The resonance tests are the investigation method of dynamic properties of structures. Their basic aim is to determine the coefficients of mass, stiffness and damping occurring in the structure equations of motion. The paper presents some new possibilities of using resonant tests to identify and interpret the phenomena occurring in dynamically loaded structures.
Źródło:: Prace Instytutu Lotnictwa; 2011, 5 (214); 3-14
0509-6669
2300-5408
Pojawia się w:: Prace Instytutu Lotnictwa
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Theoretical and experimental investigation of a ground resonance phenomenon for the ILX-27 UAV helicopter
Autorzy:: Kowaleczko, G.
Gorecki, T.
Powiązania:: https://bibliotekanauki.pl/articles/245785.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: ground resonance
dynamics of helicopter structure
finite element method
simulation
ground tests
Opis:: Ground resonance is an unbalance of the helicopter main rotor rotation caused by its asymmetry. Whilst the helicopter is in contact with the ground this asymmetry generates a divergent and often destructive oscillations of the helicopter structure. These oscillations are self-excited. This paper present results of both theoretical and experimental investigations of this phenomenon. They were dedicated to the new polish UAV helicopter ILX-27. The theoretical analysis were done with commercial software ANSYS using Finite Element Method. The virtual model of the helicopter model accurately reproduced the geometry of all elements of the helicopter and was easy to modify to simulate various kinds of damages. Calculations were done for the following cases: C1 – the helicopter standing on the ground with zero thrust of the rotor, C2 = C1 + helicopter with additional support of the rotor mast, C3 = C2 + thrust of the rotor equal to the total mass of the helicopter, C4 = C2 + fixing the helicopter to the ground, C5 = C2 + helicopter with additional mass. At the beginning the modal analysis for all cases was done – natural frequencies and modes of the structure were identified. Next, for selected cases, harmonic analysis was performed – the structure of the helicopter was loaded with concentrated harmonic forces. Finally the dynamic analysis gave time courses of blades and the hub center motions in the case of structural damages. All phases of simulations were correlated with ground tests of the helicopter prototype. This allowed to compare results of theoretical investigations. These results also supported tests of the prototype.
Źródło:: Journal of KONES; 2017, 24, 4; 91-98
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Experimental and theoretical studies of resonance effects during confined flow in silos
Autorzy:: Niedostatkiewicz, M.
Tejchman, J.
Powiązania:: https://bibliotekanauki.pl/articles/1955770.pdf
Data publikacji:: 2003
Wydawca:: Politechnika Gdańska
Tematy:: bulk solid
cohesion
dynamic effects
finite element method
model tests
polar elastoplasticity
resonance
silos
Opis:: The paper deals with experimental and theoretical research of resonance effects during silo emptying. The influence of resonance effects on wall pressures in silos has been investigated with model tests and FE analyses. The model tests were carried out with a cylindrical and rectangular silo containing various cohesive and non-cohesive bulk solids. The onset of dynamic silo flow was simulated with controlled outlet velocity along the bottom in a plane strain model and large silo. The confined flow of dry sand in a silo with parallel walls during resonance was described with a finite element method based on a polar elasto-plastic constitutive law. It differs from the conventional theory of plasticity by the presence of Cosserat rotations and couple stresses using mean grain diameter as a characteristic length. In the FE calculations, the silo walls were taken into account.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 4; 595-610
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Nieliniowości częstotliwości drgań rezonansowych lekkich płatowców
Nonlinearities of resonance vibrations of light airplanes
Autorzy:: Krzymień, W.
Powiązania:: https://bibliotekanauki.pl/articles/212902.pdf
Data publikacji:: 2011
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:: badania flatterowe samolotów
badania właściwości drganiowych
właściwości aeroelastyczne
drgania rezonansowe lekkich płatowców
flutter tests of aircraft structures
aero-elastic properties
resonance vibrations of light airplanes
tests of vibration
Opis:: Badania właściwości drganiowych obiektu jakim jest lekki samolot lub szybowiec ma na celu uzyskanie informacji potrzebnych do analizy jej właściwości aeroelastycznych oraz o drganiach występujących podczas eksploatacji. Nowoczesna technika pomiarowa wprowadza wiele nowych przyrządów, technik pomiaru oraz metod analizy drgań obiektu, które przede wszystkim zwiększają szybkość pomiarów jak również dokładniej opisują odkształcenia obiektu czyli postać drgań. Ich metodyka opiera się zwykle na założeniu liniowych (stałych) właściwości drganiowych obiektu. Stosowaną w Instytucie Lotnictwa metodykę badań rezonansowych uzupełnia badanie zależności częstości rezonansowej od amplitudy wzbudzanych drgań. Przedstawione poniżej wnioski z analizy wyników badań rezonansowych powinny być przydatne przy badaniach flatterowych w locie oraz przy analizie drgań występujących podczas eksploatacji.
Ground Vibration Testing (GVT) of airplanes is the main method to examine a structure and verify its computational models. The author has attempted to analyse the results of nonlinearities of resonance vibrations based on GVT results carried out at the Institute of Aviation for many aircraft and gliders. The results taken into consideration are typical vibration shapes for: 3 dynamically similar models of airplanes, 8 gliders, 4 composite material-made airplanes and 12 metal-made airplanes. All the GVT results for these objects were obtained by the same methods. The resulting nonlinearities of frequencies are presented as the mean values in relation to the typical shapes and type of aircraft structure. The reasons for vibration nonlinearities are usually small gaps and dry frictions in the joints between the airplane elements. The results presented can be useful for flutter calculations and in-flight flutter tests.
Źródło:: Prace Instytutu Lotnictwa; 2011, 11 (220); 77-83
0509-6669
2300-5408
Pojawia się w:: Prace Instytutu Lotnictwa
Dostawca treści:: Biblioteka Nauki

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