Analysis of Limit-Cycle Response in Fluid-Film Journal Bearings Using the Method of Multiple Scales

Gardner, Murray F.; Myers, Christopher; Savage, M.; Taylor, C. M.

doi:10.1093/qjmam/38.1.27

Cited by 27 publications

(24 citation statements)

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“…On the assumption of continuous stiffness, some scholars have established a simple continuous loosening model [41][42], and proposed that the change of the total stiffness of the system under the condition of looseness depends on the joint action of its own slow-varying characteristics and looseness phenomenon. Based on the assumption of nonlinear excitation force of bearing, such as Gardner M. et al [43], the weak nonlinear motion of long bearing and short bearing is analyzed by multi-scale method. Adams M.L.…”

Section: Based On the Parametric Analysis The Most Basic Problem Poimentioning

confidence: 99%

The Proposal and Research on the Most Basic Problem of Fault Diagnosis

Jun¹

2020

Preprint

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By keep asking “what happened to the part that was connected between normal and fault?” The basic problem of fault diagnosis is put forward. Based on the parameter analysis, the most basic problem of fault diagnosis is pointed to the generalized stiffness looseness through the congenital underlying logic presupposition of the fault. The relationship between generalized looseness, part fault and system fault is analyzed by analytic method, which further proves that looseness fault is the most basic problem in fault diagnosis.Finally, the essential priority of looseness fault in fault diagnosis is expounded.The essential priority of loosening fault in fault diagnosis explains the basic problem of fault diagnosis and provides a scientific basis for the systematic development of fault diagnosis.

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Section: Based On the Parametric Analysis The Most Basic Problem Poimentioning

confidence: 99%

The Proposal and Research on the Most Basic Problem of Fault Diagnosis

Jun¹

2020

Preprint

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“…To determine the stability of the system, equation (1) is approximated by a linear equation for small nondimensional displacements about the steady-state position, given by in which x~=x¯-x¯ss and y~=y¯-y¯ss where the subscript ss denotes steady-state. Expressions for the stiffness and damping coefficients for the SBM and LBM are given in Refs., 12,20,22 . They are tabulated in Table 1 and plotted for the SBM only in Figure 2(a) and (b), respectively, as a function of the steady-state eccentricity ratio nss.…”

Section: Bearing Stiffness and Damping Coefficientsmentioning

confidence: 99%

“…The film is assumed to rotate with the journal as opposed to being static as in Ref. 27 A discussion on the various cavitation models is given in Refs. 19,20 It should be noted that the two-orthogonal-coupled-oscillator model discussed in this article is based on a simplified approach, which has limitations when applied to real machines.…”

Section: Introductionmentioning

confidence: 99%

A perspective on oil-whirl using two orthogonal coupled oscillators

Brennan

Kamesh

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

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It has been known for many years that rotating machinery with hydrodynamic oil-film bearings can exhibit oil-whirl instability, where the unidirectional oil-film force acts on the rotor causing it to vibrate at a natural frequency. In this article, this phenomenon is investigated using two orthogonal coupled oscillators in which the bearing is modeled using short-bearing theory and an oscillating π oil-film to account for cavitation. It is found that at the point of instability, energy is extracted from the oil-film by one of the oscillators, and this energy is dissipated by the other one, such that there is no net energy gain or loss from the system. When the steady-state eccentricity ratio is such that the whirl frequency goes to zero, the oscillators effectively become undamped so that there is no energy exchange between them, and the system is stable.

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“…Gardener et al. 4 analyzed the weakly nonlinear motion of the journal bearing when the position of static equilibrium becomes linearly unstable. Myers 5 firstly applied bifurcation theory to study oil whirl in the hydrodynamic journal bearings.…”

Section: Introductionmentioning

confidence: 99%

“…Lund and Saibel 3 solved the nonlinear motion equations by the method of averaging and determined the limit whirl cycles at a narrow speed range around the threshold speed. Gardener et al 4 analyzed the weakly nonlinear motion of the journal bearing when the position of static equilibrium becomes linearly unstable. Myers 5 firstly applied bifurcation theory to study oil whirl in the hydrodynamic journal bearings.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of nonlinear stability boundaries for orifice-compensated hole-entry hybrid journal bearings

Chen

Cao

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part J:

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A high-performance and finite-length bearing system requires that the shaft can be stabilized even under a strong perturbation. The linear stability theory neglects the effects of nonlinear forces and the initial point of the shaft. Therefore, the stability of the bearing system is largely determined by the rotating speed of the shaft. In the present numerical investigation, the nonlinear forces and initial point of the shaft are accounted for to obtain the nonlinear stability boundary. The objective of this study is extended to orifice-compensated and hole-entry hybrid journal bearings with finite length. The critical rotating speed and the shaft center trajectory are acquired by solving Reynolds equation using the finite element method. By identifying the states of the orbits (stable or unstable), the nonlinear stability boundaries can be obtained. Results show that for the hybrid bearing system under the nonlinear conditions, the critical speed is a determinant factor while the initial location is another key factor. The shaft can be unstable if the initial point is outside of the stability boundary, although the speed is lower than the critical speed. There exists an obvious transitional region between the stable and unstable condition when the speed approaches the critical speed.

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Analysis of Limit-Cycle Response in Fluid-Film Journal Bearings Using the Method of Multiple Scales

Cited by 27 publications

References 0 publications

The Proposal and Research on the Most Basic Problem of Fault Diagnosis

The Proposal and Research on the Most Basic Problem of Fault Diagnosis

A perspective on oil-whirl using two orthogonal coupled oscillators

Numerical study of nonlinear stability boundaries for orifice-compensated hole-entry hybrid journal bearings

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