Wyniki wyszukiwania - Biblioteka Nauki

1

Gyroscopic Effect in the Stability Problem of a Slender Rotating Shaft with Follower Load

100%

Kurnik W. , Przybyłowicz P. M. , Weronko J. , Wiatr P.

Machine Dynamics Problems

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2003

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tom Vol. 27, No. 2

55-70

EN

The paper is concerned with stability analysis of a flexible rotating shaft supported as a cantilever beam and subjected to tip-concentrated follower load. Such systems exhibit two mechanisms of instability of flutter type, different in physical nature and, what is most important, interacting to produce complicated stability regions in the space of rotation speed and follower load. In such systems even for high-speed working conditions, the rotary inertia as well as the gyroscopic effect is usually neglected like in slender beams. However, in some regions of parameters, especially in slightly internally dissipative shafts the gyroscopic effect can considerably change the boundaries of the stability domain. Moreover, an interesting phenomenon can be observed when two pairs of eigenvalues with different speeds at the same time intersect the imaginary axis of the complex plane. This leads to bifurcation with four critical eigenvalues similar to that studied by Iooss in the Navier-Stokes equations.

2

Dynamics of the air blower with gyroscopic couple

100%

Vasylius M. , Augustaitis V. , Barzdaitis V. , Bogdevicius M.

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tom Vol. 2, no. 3

95-98

EN

To avoid damaging of tilting pad journal bearings, the problem of safety shut down of high speed air blower cantilever rotor becoming important in modern industry. The experimental testing, modeling and simulation of dynamic behavior of rotating system was run to directly evaluate gyroscopic negative effect damaging journal bearings. A dynamic model of air blower rotating system was designed and simulated. A simulation and experimental measurement results of rotating system were used to optimize the shut down regime of machine. Gyroscopic effect influences of rotor bearing stability are confirmed. Results of numerical simulation confirm results of experimental vibration measuring. The theoretical research results are given and conclusions are made. Experimental testing and simulations results was applied to typical air blower rotating systems for elimination of huge negative forces acting on new bearings during shut down of the machine.

3

Efekt żyroskopowy w dynamice walców maszyny papierniczej

75%

Zachwieja J.

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tom Z. 53(241)

311-323

PL

Praca zawiera analizę wpływu efektu żyroskopowego na wartość prędkości krytycznej walca prowadzącego wstęgę papieru w krajarce KL63. Wykazano, że stosunkowo duża jego sztywność wpływ ten znacząco ogranicza. W identyczny sposób oddziałuje wzrost podatności podparcia walca.

EN

The work contains an analysis of gyroscopic effect influence on a critical speed value of cylinder that leads a band of paper in a KL63 cutter. It was proved that its relatively high stiffness limits this influence very much. The same effect is achieved by an increase of flexibility of cylinder support.

4

Development of identification procedure for the internal and external damping in a cracked rotor system undergoing forward and backward whirls

51%

Roy D. K. , Tiwari R.

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tom Vol. LXVI, nr 2

229--255

EN

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.

5

Impact analysis of gyroscopic effects on motorcycle’s stability

51%

Grzegożek W. , Weigel-Milleret K.

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tom nr 4

3556--3562, CD2

EN

Stability, which is one of the more important properties of single-track vehicles, defined as its resistance to interference or disturbance and returning the motorbike to ride straight ahead after riding in a turn depends on many factors. The influence of gyroscopic effects of the motorcycle on its stability was analyzed on a specially designed drum bench stand. The role of the gyroscopic effect in motorbike designs is significant. The study included wobble vibrations for different speeds and different angles of the front fork of the motorcycle, with and without the gyroscopic effect. The paper contains a description of the issues of vibration occurring in single-track vehicles, description of the bench test and compilation of the results.

PL

Stateczność, stabilność (ang. stability) motocykla, będąca jedną z ważniejszych właściwości pojazdów, rozumianą jako jego odporność na działanie zakłóceń czy zaburzeń w czasie ruchu prostoliniowego, powrotu do jazdy na wprost po wystąpieniu takiego zaburzenia a także wystąpienia niepożądanych form ruchu, zależy od wielu czynników. Podjęto próbę wykonania badań wpływu efektów żyroskopowych motocykla na jego stabilność na specjalnie skonstruowanym bębnowym stanowisku badawczym. Wpływ efektów żyroskopowych nie może być pomijany w rozważaniach o stabilności. Badaniami objęto drgania typu wobble dla różnych prędkości i różnych kątów pochylenia przedniego widelca motocykla z i bez efektu żyroskopowego. Praca zawiera opis zagadnień drganiowych występujących w pojazdach jednośladowych, opis wykonanego stanowiska badawczego a także metodykę i sposób przeprowadzenia badań oraz opis opracowanych wyników.