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Infulence of Geometry Imperfections on Flexural-Torsional Vibrations in Rotating Systems

Łazarz B., Matyja T.

Machine Dynamics Research

2015

Vol. 39, No. 2

97-110

In paper we investigated the influence of geometry imperfections on coupled flexural-torsional vibrations in the transient states, at start-up, in rotating systems. Consideration was given to two types of errors: the permanent deflection of a shaft in place of rotors installation (shaft bow) and inclination of a rotor plane with respect to the designed axis of rotation of the machine (angular misalignment). Used was the specialist Simulink library developed by the authors.

Diagnozowanie maszyn tłokowych z wykorzystaniem przebiegów procesów roboczych.

Bielawski P.

Zagadnienia Eksploatacji Maszyn

2004

Vol. 39, nr 4

161-176

Wskazano na znaczenie przebiegu ciśnienia w komorze roboczej maszyny tłokowej w sterowaniu i diagnozowaniu. Wymieniono możliwości i ograniczenia bezpośredniego pomiaru przebiegu ciśnienia. Wskazano na metody wyznaczania ciśnienia czynnika roboczego z przebiegów drgań elementów maszyny. Przedstawiono możliwości wykorzystania przebiegu ciśnienia jako sygnału diagnostycznego. Wykazano możliwość wykorzystania różnicy między przebiegami ciśnień wyznaczonych z bezpośredniego pomiaru i z przebiegu drgań skrętnych wału korbowego maszyny, do diagnozowania węzłów tribologicznych mechanizmu tłokowo-korbowego.

Rotational speed and torsional vibration in piston machinery depend on courses of working processes because course of pressure in working chamber determines forces acting on piston. Quality assessment of courses of working pressures can be done on the basis of courses of torsional vibration. There is possible to reproduce courses of working pressures knowing or calculating transfer function for the whole piston - connecting rod mechanism. Comparison of pressure courses calculated simultaneously from working chamber and from crankshaft side creates possibility of concluding not only about condition of working chamber elements but condition of tribological pairs of piston - connecting rod set as well that means condition of crosshead, bottom end and main bearings. More convenient in this case can be comparison of courses of crank pin efforts (tangential forces acting on crank pins of piston machine) determined from simultaneously measured working pressures and torsional vibration. Organized thermodynamic processes are executed in working chambers of piston machines (engines, compressors and pumps). Thermodynamic processes occurred there, are thermal cycles often presented in set of p - V coordinates (pressure of working factor - volume of working chamber). Course of real pressure of working factor depends on course of all particular processes and depends on condition state of elements created working chamber. For that reason cycles p=V are utilized to quality and quantitative assessment of working pressure and to assess technical state of working chamber elements. Determination of p - V cycle demands to solve a number of problems dependent on type and construction of machine. The most accurate measurements are carried out by direct measurement of pressure by means of transducer attached to the wall of working chamber. The bases of diagnosis concluding are differences between the measured course and the pattern course evaluated for particular machine. There is possible indirect measurement of pressure based on reproduction of course of working pressure from course of vibration of working chamber wall. For such a calculation, knowledge or determination so called transfer function in frequency domain is essential.