Dynamic coefficients of finite length journal bearing. Evaluation using a regular perturbation method

Merelli, Claudio Ernesto; Barilá, Daniel O.; Vignolo, Gustavo G.; Quinzani, Lidia M.

doi:10.1016/j.ijmecsci.2018.11.018

Cited by 27 publications

(7 citation statements)

References 30 publications

(77 reference statements)

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“…These two approximate solutions allow a direct expression of the fluid-film forces. Approximate analytical solutions for finite length journal bearings with length-todiameter ratio around 1 also exist [25,26] . As a representative of this class of hydrodynamic forces, e.g solution introduced in [24] can be mentioned.…”

Section: Linearization Of Fluid-film Forcesmentioning

confidence: 92%

Predictive capability of various linearization approaches for floating-ring bearings in nonlinear dynamics of turbochargers

Dyk

Smolík

Rendl

2020

Mechanism and Machine Theory

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A floating-ring bearing (FRB) is composed of a journal, a floating ring and a housing which are separated by two thin oil films. This system is inherently nonlinear and if it is lightly loaded or operated at high speeds, it is prone to the fluid-induced instability. The threshold speed for the instability of a journal bearing with one oil film can be estimated using linearized forces acting in the film. However, the linear analysis of FRB might be problematic because results of such an analysis are usually difficult to interpret. Nevertheless, the linear analysis can provide some fundamental insights into system behaviour. This work aims to evaluate in detail the use of linear theory in the stability analysis of rotating systems supported on FRBs. Several approaches for the linearization of the forces acting in FRB are proposed and analysed. The results are visualized in the form of a holistic Campbell diagram which together depicts natural frequencies, whirl frequencies, modal damping and precession of mode shapes. Moreover, it is demonstrated that the holistic Campbell diagram can be used to interpret-and to some extent, also to predict-results of nonlinear analysis.

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Section: Linearization Of Fluid-film Forcesmentioning

confidence: 92%

Predictive capability of various linearization approaches for floating-ring bearings in nonlinear dynamics of turbochargers

Dyk

Smolík

Rendl

2020

Mechanism and Machine Theory

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“…For journal bearings, the length to diameter ratio is an important factor for the lubricant film conditions. From the view of mathematic analysis, the Reynolds equation can be simplified for both high and low length to diameter ratio conditions (Merelli et al , 2019), and the corresponding analytical solutions were proposed by researchers at early times (Dobrica and Fillon, 2009; Hamdavi et al , 2017; Mao et al , 2020). However, for finite journal bearings, i.e.…”

Section: Introductionmentioning

confidence: 99%

A solution for finite journal bearings by using physics-informed neural networks with both soft and hard constrains

Yang

Deng

2023

ILT

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Purpose The purpose of this study is to solve the Reynolds equation for finite journal bearings by using the physics-informed neural networks (PINNs) method. As a meshless method, it is unnecessary to use big data to train the neural networks, but to satisfy the Reynolds equation and the corresponding boundary conditions by using the known physics information. Design/methodology/approach Here, the boundary conditions are enforced through the loss function firstly, i.e. the soft constrain method. After this, an equation was constructed to build a surrogate model for satisfying the corresponding boundary conditions naturally, i.e. the hard constrain method. Findings For the soft one, in brief, the pressure results agree well with existing results, apart from the ones on the boundaries. While for the hard one, it can be noted that the discrepancies on the boundaries are reduced significantly. Originality/value The PINNs method is used to solve the Reynolds equation for finite journal bearings, and the error values on the boundaries for the results of the soft constrain method are improved by using the hard constrain method. Therefore, the hard constraint maybe also a good option when the pressure results on the boundaries are emphasized. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2023-0045/

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“…The consideration of the nonlinear bearing forces in rotordynamic simulations requires the equation of motion of the rotor to be solved in the time domain, by means of time integration schemes, while the Reynolds equation [4] is solved at every time step. The latter is a partial differential equation describing the pressure generation in the lubrication gap and is usually solved by means of analytical methods [5][6][7][8][9][10], look-up table techniques [11], or numerical models [12][13][14]. Amongst these approaches, only the numerical solution provides accurate results under general boundary conditions (BCs) and is able to consider shaft tilting [15], mass-conserving cavitation [16], elasto-hydrodynamics [17,18], thermo-hydrodynamics [19], or hydraulic coupling of oil films [20].…”

Section: Introductionmentioning

confidence: 99%

SBFEM with reduced modal basis for hydrodynamic bearings

Pfeil,

Song,

Woschke

2023

Proc Appl Math and Mech

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The numerical effort of transient rotordynamic simulations is often dominated by the computation of nonlinear hydrodynamic bearing forces. These forces are described by the Reynolds equation and need to be computed at every time step. Usually, numerical models, analytical approximations, or look‐up table techniques are employed, depending on the desired tradeoff between accuracy and computational cost. In recent studies, a semi‐analytical approach based on the scaled boundary finite element method (SBFEM) has been developed as an efficient alternative to these methods. The partial differential equation is transformed into a system of ordinary differential equations, leading to an eigenvalue problem. Here, the numerical effort can be further decreased by means of a modal reduction, which is investigated in this study. The shaft eccentricity determines the smoothness of the hydrodynamic pressure field and is identified as an adequate indicator as to what subset of eigenvalues and eigenvectors should be considered in the solution.

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Dynamic coefficients of finite length journal bearing. Evaluation using a regular perturbation method

Cited by 27 publications

References 30 publications

Predictive capability of various linearization approaches for floating-ring bearings in nonlinear dynamics of turbochargers

Predictive capability of various linearization approaches for floating-ring bearings in nonlinear dynamics of turbochargers

A solution for finite journal bearings by using physics-informed neural networks with both soft and hard constrains

SBFEM with reduced modal basis for hydrodynamic bearings

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