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Wyświetlanie 1-7 z 7
Tytuł:
Experimental identification of rotating and stationary damping in a cracked rotor system with an offset disc
Autorzy:
Roy, Dipendra K.
Tiwari, Rajiv
Powiązania:
https://bibliotekanauki.pl/articles/140313.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rotating (internal) damping
stationary (external) damping
gyroscopic effect
switching crack
unbalance
full-spectrum
Opis:
In the rotor system, depending upon the ratio of rotating (internal) damping and stationary (external) damping, above the critical speed may develop instability regions. The crack adds to the rotating damping due to the rubbing action between two faces of a breathing crack. Therefore, there is a need to estimate the rotating damping and other system parameters based on experimental investigation. This paper deals with a physical model based an experimental identification of the rotating and stationary damping, unbalance, and crack additive stiffness in a cracked rotor system. The model of the breathing crack is considered as of a switching force function, which gives an excitation in multiple harmonics and leads to rotor whirls in the forward and backward directions. According to the rotor system model considered, equations of motion have been derived, and it is converted into the frequency domain for developing the estimation equation. To validate the methodology in an experimental setup, the measured time domain responses are converted into frequency domain and are utilized in the developed identification algorithm to estimate the rotor parameters. The identified parameters through the experimental data are used in the analytical rotor model to generate responses and to compare them with experimental responses.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 4; 447-474
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental identification of cracked rotor system parameters from the forward and backward whirl responses
Autorzy:
Shravankumar, C.
Tiwari, Rajiv
Powiązania:
https://bibliotekanauki.pl/articles/140263.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
development of fatigue crack
crack flexibility
directional (full) spectrum
higher harmonics
forward and backward whirl
Opis:
In the present work, an experimental investigation of a transverse fatigue crack has been carried out. A mathematical modelling of cracked rotor system along with the measured vibration is used to find crack parameters that not only detect the fault but also quantify it. Many experimental studies on cracks considered the crack as a slit or notch, which remains open. However, such flaws do not mimic a fatigue crack behavior, in which crack front opens and closes (i.e., breathes in a single revolution of the rotor). The fatigue crack in rotors commonly depicts 2× frequency component in the response, as well as higher frequency components, such as 3×, 4× and so on. In rotors, both forward and backward whirling take place due to asymmetry in rotor, and thus the fatigue crack gives the forward and backward whirl for all such harmonics. A rotor test rig was developed with a fatigue crack in it; rotor motions in two orthogonal directions were captured from the rig at discrete rotor angular speeds using proximity probes. The directional-spectrum processing technique has been utilized to the measured displacements to get its forward and backward whirl components. Subsequently, it is executed in a mathematical model-based estimation procedure to obtain the crack forces, residual unbalances, and remaining rotor system unknown variables. Estimation of crack forces during rotation of the shaft gives its characteristics, which can be used further to develop newer crack models.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 3; 329-353
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of identification procedure for the internal and external damping in a cracked rotor system undergoing forward and backward whirls
Autorzy:
Roy, Dipendra Kumar
Tiwari, Rajiv
Powiązania:
https://bibliotekanauki.pl/articles/139607.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
internal damping
external damping
gyroscopic effect
switching crack
unbalance
full-spectrum
tłumienie wewnętrzne
tłumienie zewnętrzne
efekt żyroskopowy
zmieniające się pęknięcie
brak równowagi
pełne spektrum
Opis:
In the present work, a procedure for the estimation of internal damping in a cracked rotor system is described. The internal (or rotating) damping is one of the important rotor system parameters and it contributes to the instability of the system above its critical speed. A rotor with a crack during fatigue loading has rubbing action between the two crack faces, which contributes to the internal damping. Hence, internal damping estimation also can be an indicator of the presence of a crack. A cracked rotor system with an offset disc, which incorporates the rotary and translatory of inertia and gyroscopic effect of the disc is considered. The transverse crack is modeled based on the switching crack assumption, which gives multiple harmonics excitation to the rotor system. Moreover, due to the crack asymmetry, the multiple harmonic excitations leads to the forward and backward whirls in the rotor orbit. Based on equations of motions derived in the frequency domain (full spectrum), an estimation procedure is evolved to identify the internal and external damping, the additive crack stiffness and unbalance in the rotor system. Numerically, the identification procedure is tested using noisy responses and bias errors in system parameters.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 2; 229-255
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Definition of the Load Spectrum for SU-22 Fighter-Bomber Full Scale Fatigue Test
Autorzy:
Reymer, P.
Kurdelski, M.
Leski, A.
Jankowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/97893.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
full scale fatigue test
Su-22 fighter-bomber
load spectrum
Opis:
The Su-22 fighter-bomber is a military aircraft used in the Polish Air Force since the mid 1980’s. By the decision of the Polish Ministry of Defense the predicted service life for this type of aircraft will be extended to 3200 flight hours. Due to the fact that some aircraft were nearing the end of the service life guaranteed by the manufacturer, the actual service life, determined based on the flight profile in the Polish Air Force, had to be validated. Consequently, the Full Scale Fatigue Test (FSFT) had to be carried out in order to verify that the required service life was attainable. This article describes the process of preparation of the load spectra used in the Su-22 FSFT. Due to the fact that the Su-22 has a variable sweep wing the whole test was divided into three Stages (landing, flight and flap loads) carried out at different wing sweep angles (30°/45°/30°). The spectra were developed using the historical data gathered from Flight Data Recorders (FDR), strain signals acquired during the Operational Load Monitoring program (OLM) and aerodynamic calculations.
Źródło:
Fatigue of Aircraft Structures; 2015, 7; 28-33
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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