Nonlinear responses and bifurcations of a rotor-bearing system supported by squeeze-film damper with retainer spring sub
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ORIGINAL PAPER
Nonlinear responses and bifurcations of a rotor-bearing system supported by squeeze-film damper with retainer spring subjected to base excitations Xi Chen
. Xiaohua Gan . Guangming Ren
Received: 14 March 2020 / Accepted: 23 October 2020 Ó Springer Nature B.V. 2020
Abstract A high-speed rotating rotor system mounted on a moving vehicle is inevitably subjected to parametric excitations and exciting forces induced by base motions. Dynamic characteristics of a rotorbearing system supported by squeeze-film damper with retainer spring subjected to unbalance and support motions are investigated. Using Lagrange’s principle, equations of motion for rotor system relative to a moving support are derived. Under base excitations, steady-state and transient responses are analyzed by frequency–amplitude curve, waveform, orbit, frequency spectrum, and Poincare´ map. Changing with rotating speed or base harmonic frequency, journal motions are analyzed by bifurcation diagram. The results indicate that under base axial rotation, increasing base angular velocity, first two critical speeds decrease but resonant amplitudes increase slightly. The journal whirls around the static eccentricity with noncircular orbit. Under base lateral rotation, critical speeds, and resonant amplitudes remain essentially unchanged, but orbit’s deviation is related to base angular velocity. Excited by base harmonic translation, the integral multiples of fundamental frequency kXðk ¼ 1; 2Þ, base harmonic frequency Xz , and combined frequencies
X. Chen (&) X. Gan G. Ren Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, China e-mail: [email protected]
kX jXz ðk; j ¼ 1; 2Þ are stimulated, changing the motions from periodic to quasiperiodic. Overall, it provides a flexible approach with good expandability to predict dynamic characteristics of squeeze-film damped rotor system under base motions. Keywords Base excitations Bifurcation Squeeze film damper Static eccentricity Nonlinear response
1 Introduction Aero-engines and gas turbines, mounted on moving support systems like aircrafts and ships, not only operate at high rotating speeds under variable load conditions, but also are exposed to potential dangerous base movements such as maneuvering flights and shock waves. Such base motions may result in severe vibrations and even abnormal operation of flexible rotor shafts. Therefore, it is necessary to investigate dynamic characteristics of squeeze-film damped rotor system subjected to base excitations to provide support for optimizing structural design and improving structural reliability. Squeeze film damper (SFD) is widely mounted on the rolling bearing of aero-engine’s rotor system to provide additional external damping and to suppress rotor vibration, especially when passing through critical speeds. Due to oil-film forces with high
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nonlinearity, it may generate nonlinear dynamic problems s
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