Dynamic stability and bifurcation phenomena of an axially loaded flexible shaft-disk system supported by flexible bearing:
26 Mar 2020-Vol. 234, Iss: 15, pp 2951-2967
TL;DR: In this paper, the vibration and bifurcation analysis of a spinning rotor-disk-bearing system is performed to carefully scrutinize the dynamic stability under extrinsic mass unbalance and pulsatin imbalance.
Abstract: The present research studies the vibration and bifurcation analysis of a spinning rotor-disk-bearing system to carefully scrutinize the dynamic stability under extrinsic mass unbalance and pulsatin...
Citations
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TL;DR: In this paper , a unified modeling approach for rotating flexible shaft-disk systems based on continuum theory is proposed, which can be easily extended to complex rotor systems with multiple flexible disks and supports under general boundary and coupling conditions.
9 citations
TL;DR: In this paper, the parametric instability of a rotor system with electromechanically coupled boundary conditions under periodic axial loads is studied based on the current flowing piezoelectric shunt damping technique, the detailed rotor model is established by the finite element (FE) method.
Abstract: The parametric instability of a rotor system with electromechanically coupled boundary conditions under periodic axial loads is studied Based on the current flowing piezoelectric shunt damping technique, the detailed rotor model is established by the finite element (FE) method In the matrix assembly procedure, a novel simple process is proposed to make the equations of shunt circuits more conveniently to be introduced into the global FE equations The discrete state transition matrix method which is used for determining the influence of circuit parameters on instability regions in this paper has also been presented The numerical simulation shows that only the combination instability regions exist when the shaft is rotating The mechanical damping has different effect on the simple and combined instability regions These two points are consistent with the previous references, which verifies the obtained FE model In addition, the simulated results also reveal that the introduction of shunt circuits has little influence on the rotor’s original whirling frequencies It gives rise to the appearance of new synchronous whirl modes The new whirling frequencies are combined with the original ones to form the new combination instability regions Furthermore, the resistance of shunt circuits has the same performance as the mechanical damping has That is, moving up the start points of instability regions and expanding its width
6 citations
TL;DR: In this article , a typical failure mechanism (rotor unbalance, rotor friction, and rotor crack) and vibration characteristics of the turbocharger rotor system was established by an improved four-node aggregate parameter method.
Abstract: To study the typical failure mechanism (rotor unbalance, rotor friction, and rotor crack) and vibration characteristics of the turbocharger rotor system, a rotor system dynamics simulation model was established by an improved four-node aggregate parameter method. The geometric and physical characteristics of the rotor system under three failure states and its dynamics under operation were analyzed. Thus, a typical failure dynamics simulation model of the rotor system was established. On this basis, the output failure simulation signal was extracted using the Hu invariant moment feature extraction method to analyze the system vibration characteristics under each typical failure state of the rotor system. The results show that the model in this paper can effectively reduce the computational volume and computational time, and the errors of numerical simulation were less than 3%. When an unbalance fault occurred in the rotor system, the shaft trajectory was “0” shaped and the response spectrum was dominated by 1X. When the rotor system was frictional, the shaft trajectory was a slightly concave “8” shape, and the response spectrum was dominated by 0.5X. When the rotor system was cracked, the axial trajectory was a “vortex”, and the response spectrum was dominated by 0.5X. Thus, the study of typical failure mechanism and vibration characteristics of a turbocharger rotor system by simulation calculation is effective and has good research prospects, providing an important technical reference for dynamic analysis and fault diagnosis of the rotor system.
1 citations
TL;DR: In this article , the exact whirl frequency equation is derived analytically for different boundary conditions, including pinned-pinned, clamped-clamped, free-free, and elastic supports.
Abstract: This paper deals with the flexural vibration and dynamic stability of a spinning shaft subjected to partial load. Based on the theorem of moment of momentum and the theorem of motion of center of mass, the governing equation of motion for the spinning shaft system is obtained. Four kinds of boundary conditions including pinned-pinned, clamped-clamped, free-free, and elastic supports are considered. The exact whirl frequency equation is derived analytically for different boundary conditions. The obtained model is confirmed by comparing with the results reported in the available literature, and excellent agreement is presented. A numerical investigation is carried out to examine the effects of support stiffness, mass ratio, eccentric distance, and slenderness ratio on the whirl characteristics and stability of the system in terms of the obtained model. The results show that the whirl frequency and critical spinning speed of the system are dependent on these parameters, and the stability is mainly governed by the mass ratio and eccentric distance.
References
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TL;DR: In this paper, the analysis of nonlinear phenomena with a focus on investigating the bifurcations and chaotic behaviour of an elastically induced flexible rotor-bearing system subjected to a harmonic ground motion has been studied.
Abstract: The assessment of nonlinear phenomena with a focus on investigating the bifurcations and chaotic behaviour of an elastically induced flexible rotor-bearing system subjected to a harmonic ground motion has been studied. The higher-order Euler–Bernoulli deformation theorem has been adopted that governs the nonlinear dynamic characteristics of the rotating system. Nonlinear vibration analysis has been carried out to determine the critical speeds, i.e., Campbell diagram followed by demonstrating the inherent nonlinear signatures through the illustration of time history, Fourier spectrum and Poincare’s map upon varying the system design variables. The perturbation technique has been used to obtain the approximate nonlinear solutions from a set of polynomial algebraic equations under steady-state condition in various resonance cases. Further, stability analysis along with successive bifurcations of the solutions has been investigated. The present nonlinear model formulated based on Euler theory has been found to be capable enough to predict the correct value of critical speeds and dynamic responses in comparison with that of model developed based on Timoshenko theory. The present outcomes can offer immense practical importance for any application of the flexible rotor-bearing system when it performs high-speed operation.
10 citations
"Dynamic stability and bifurcation p..." refers background in this paper
...Phadatare et al.19 investigated the vibration behavior of the rotating system comprising a nonlinear flexible shaft and a rigid disk under moving platform with an unbalance mass while in another study, Phadatare et al.20 analyzed the free vibration behavior of the large deflection model of highly flexible rotating system....
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...Phadatare et al.(19) investigated the vibration behavior of the rotating system comprising a nonlinear flexible shaft and a rigid disk under moving platform with an unbalance mass while in another study, Phadatare et al....
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TL;DR: In this article, the effects of the spectral density of random axial load and the polar mass moments of inertia on stochastic stability of the rotor system are evaluated and employed to determine the region of almost sure asymptotic stability of rotor systems.
7 citations
"Dynamic stability and bifurcation p..." refers background in this paper
...Bai et al.(13) presented a rotor system model, which is excited by stochastically axial loads....
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...Bai et al.13 presented a rotor system model, which is excited by stochastically axial loads....
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01 Oct 2001
TL;DR: In this article, the authors presented two methods to calculate the unbalance vibration response of a flexible rotor provided with a squeeze-film damper (SFD) with retainer springs.
Abstract: This paper presents two efficient methods to calculate the unbalance vibration response of a flexible rotor provided with a squeeze-film damper (SFD) with retainer springs. Both methods are iterative and combine the harmonic balance and receptance approaches. The first method, called the modified iteration method (MIM), is suitable for predicting the three-dimensional mode shapes of a concentric SFD-rotor system. The second method, called the modified harmonic balance method (MHBM), is developed to calculate the non-linear vibration response of a flexible shaft provided with either a concentric or eccentric SFD. The system is also investigated experimentally under different conditions. The predictions computed by these methods are compared with experimental measurements and reasonably good agreement is obtained.
6 citations
"Dynamic stability and bifurcation p..." refers background in this paper
...Siew et al.3 investigated the unbalanced flexible rotating system squeeze-film damper and retainer springs under different conditions....
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...Siew et al.(3) investigated the unbalanced flexible rotating system squeeze-film damper and retainer springs under different conditions....
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TL;DR: In this article, a mathematical model is developed for simulating the vibrations of a single flexible cylinder under crossflow, where the flexible tube is subjected to an axial load and has loose supports.
Abstract: In this work, a mathematical model is developed for simulating the vibrations of a single flexible cylinder under crossflow. The flexible tube is subjected to an axial load and has loose supports. The equation governing the dynamics of the tube under the influence of fluid forces (modeled using quasi-steady approach) is a partial delay differential equation (PDDE). Using the Galerkin approximation, the PDDE is converted into a finite number of delay differential equations (DDE). The obtained DDEs are used to explore the nonlinear dynamics and stability characteristics of the system. Both analytical and numerical techniques were used for analyzing the problem. The results indicate that, with high axial loads and for flow velocities beyond certain critical values, the system can undergo flutter or buckling instability. Post flutter instability, the amplitude of vibration grows until it impacts with the loose support. With a further increase in the flow velocity, through a series of period doubling bifurcations the tube motion becomes chaotic. The critical flow velocity is same with and without the loose support. However, the loose support introduces chaos. It was found that when the axial load is large, the linearized analysis over-estimates the critical flow velocity. For certain high flow velocities, limit cycles exist for axial loads beyond the critical buckling load.
4 citations
"Dynamic stability and bifurcation p..." refers background in this paper
...Sadath et al.21 analyzed the nonlinear dynamics and stability characteristics of a single flexible tube with the excitation of an axial load....
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...Sadath et al.(21) analyzed the nonlinear dynamics and stability characteristics of a single flexible tube with the excitation of an axial load....
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01 Jul 2000
TL;DR: In this paper, the bifurcation and chaos of the unbalanced response of a bearing-rotor system with non-linear suspension are investigated on the basis of the assumption of an incompressible lubricant toge
Abstract: The bifurcation and chaos of the unbalanced response of a bearing-rotor system with non-linear suspension are investigated on the basis of the assumption of an incompressible lubricant toge...
4 citations
"Dynamic stability and bifurcation p..." refers background or methods in this paper
...Yau et al.(2) investigated the stability and bifurcation of the rotor bearing system with nonlinear suspension using Poincaré maps, bifurcation diagrams and power spectra under different operating conditions....
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...It is often being observed that suspensions, ball bearing clearances, large deformation of bearing balls, seals, journal bearings, and so on, in a rotating system can contribute to nonlinearity.(2) Here, the bearings are considered to be 2D spring damper system (Figure 1(b)) with linear and cubic nonlinearity(2) in stiffness properties....
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...Yau et al.2 investigated the stability and bifurcation of the rotor bearing system with nonlinear suspension using Poincaré maps, bifurcation diagrams and power spectra under different operating conditions....
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