Stability analysis of rotating shaft under electromagnetic and bearing oil-film forces

Abstract

The stability of the fixed pints of a flexible rotor supported by journal bearings is investigated through the Bifurcation diagrams. In this paper the effect of nonlinear electromagnetic harmonic force is added to the simultaneous consideration of the effects of the nonlinearity in curvature and inertia, mass eccentricity and hydrodynamic forces of the journal bearings. Solution of the Reynolds equation renders the pressure distribution in the bearings. The bearing forces are found from integrating the pressure distribution on the surface of bearings. Derivation of the equations is performed using the Hamilton's principle and the nonlinearity terms are related to the eccentricity and the curvature of shaft. Primary and combination resonances are imposed to the rotor-bearing system and steady state responses show the effects of magnetic and bearing forces on the stability of amplitudes. In combination resonance, frequency of the electromagnetic load is tuned as the average of the forward and backward natural frequencies of the rotor. Existence of unstable Hopf points demonstrates that periodic, quasi-periodic and chaotic motions may be arisen in the nonlinear behavior of rotor.

Research on Load-Sharing Technology of Toroidal Planetary Worm Based on Sliding Oil Film Supporting Roller

“…Lubricants 2023, 10, x FOR PEER REVIEW 15 of 18 achieve a load-sharing effect. Theoretically, the floating oil film will generate the dynamic wear or surface interaction mechanisms between workpiece mating parts [7,8], such as the dynamic polished wear and floating surface mechanism of action [26,27].…”

“…Morris et al [6] presented the thermo-mixed-hydrodynamics of compression rings and big-end bearings. In addition, a floating oil film can probably influence the dynamic wear or surface interaction mechanisms between workpiece mating parts [7,8], such as floating surface mechanism of action [9,10], dynamic polished wear [7,11,12] or surface treatment with some polishing methods [13][14][15], etc. Thus, in order to improve load-sharing characteristics of the mechanism, a floating oil film load-sharing structure requires further analysis.…”

Vibration and stability analysis of a spinning shaft with arbitrary boundaries subjected to partial load

“…Spinning shafts are widely used in engineering equipment such as aero engine rotors, oil drill pipes, steam turbine rotors, and other industrial machines. As a result of extensive engineering applications, flexural vibration and instability have been studied by many researchers (Behzad and Bastami, 2004;Dimentberg, 2005;Hosseini et al, 2014;Zhu and Chung, 2015;Aouadi and Lakrad, 2018;Arvin, 2018;Gayen et al, 2018;Eftekhari et al, 2018Eftekhari et al, , 2021Elhannani et al, 2019;Saeed, 2019;Zhang et al, 2020;Li et al, 2021;Soheili and Abachizadeh, 2022). For example, Shaw and Shaw (1989) considered the effects of large transverse displacements and external sources of dissipation and investigated the instability and bifurcations of a rotating flexible shaft.…”