Linear Stability Analysis of Journal Bearings Lubricated With a Non-Newtonian Rabinowitsch Fluid

Lin, Jaw‐Ren; Hung, Tzu-Chen; Lin, C. H.

doi:10.1017/jmech.2017.48

Cited by 9 publications

(3 citation statements)

References 8 publications

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“…Khonsari and Chang 1 studied the stability boundary of short bearings based on journal centre trajectories, and found the expression of threshold speed expressed by stiffness and dampness coefficients by applying the Routh Hurwitz stability criterion on the stability characteristic equation of the journal bearing. Lin et al 2,3 discussed the effects of non-Newtonian lubricants (couple stress fluids 2 and Rabinowitsch fluids 3 ) on the linear stability of journal bearings. Tian and Chen 4 expanded the range of non-Newtonian factor during the discussion of the linear stability of journal bearings lubricated with Rabinowitsch fluids.…”

Section: Introductionmentioning

confidence: 99%

Threshold speed of short journal bearings considering the non-Gaussian longitudinal surface roughness

Tian

2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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During the actual machining process of journal surface, such as milling and fine turning, the surface roughness has strong non-Gaussianity. Thus, the effect of non-Gaussian longitudinal roughness on threshold speed of short journal bearings is investigated in this study. Introducing the parameters of kurtosis and skewness, the model of non-Gaussian surface roughness is established by modifying the Gaussian distribution. It is found that the non-Gaussianity of surface roughness cannot be neglected especially for the journal rotating with a larger eccentricity ratio, the error of Gaussian distribution surface reaches 19.33% when the eccentricity ratio equal 0.7. The increasing of kurtosis would reduce the threshold speed, while the increasing of skewness would enhance the threshold speed. For a larger eccentricity ratio, the effect of kurtosis and skewness on threshold speed is more distinctly.

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Section: Introductionmentioning

confidence: 99%

Threshold speed of short journal bearings considering the non-Gaussian longitudinal surface roughness

Tian

2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…Considering non-Newtonianism of the lubricant, Lin et al 2 illustrated the influence of couple stress on the nonlinear stability of short hydrodynamic bearings. Several years later, applying Rabinowitsch fluid model, Lin et al 3 discussed the linear stability of short hydrodynamic bearings lubricated with pseudoplastic fluids. To solve the Reynolds equation, perturbation method was applied by them which means that the non-Newtonian factor of the pseudoplastic lubricant cannot be larger than 1.…”

Section: Introductionmentioning

confidence: 99%

Discussion on dynamic characteristics of long journal bearings considering surface roughness

Tian

Chen

2022

Advances in Mechanical Engineering

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The hydrodynamic bearing is the key part of many rotating machines, and dynamic characteristics of the bearing would affect the operation performance of machines directly. Thus, this study focused on dynamic characteristics of long journal bearings and tried to illustrate the influence of surface roughness on dynamic performances of long bearings. Applying Christensen stochastic model and long bearing approximation, the modified Reynolds equation was established. To solve the modified Reynolds equation, the numerical integration method was applied. It is found that the surface roughness would significantly weaken the stability threshold speed, normal stiffness coefficients ([Formula: see text], [Formula: see text]), and crossed dampness coefficients ([Formula: see text] and [Formula: see text]) for the long bearing with a large eccentricity ratio. In summary, the influences of surface roughness cannot be ignored during discussing dynamic characteristics of long journal bearings.

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“…Lin et al 29 theoretically investigated the linear dynamic performance of short journal bearing simulated with non-Newtonian Rabinowitsch flow model. They have calculated the simulation results for Newtonian, dilatants, and pseudo-plastic fluids and have observed that dilatants/ pseudo-plastic fluids show a reverse trend in the stable region for short bearing.…”

Section: Introductionmentioning

confidence: 99%

Performance of finite bearing under the combined influence of turbulent and non-Newtonian lubrication

Soni

2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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The current numerical investigation is used to predict the dynamic performance of finite bearing considering the combined influence of turbulence regime and non-Newtonian flow. With appropriate assumptions, the Navier–Stokes and continuity equation have been revised by the linear turbulence and non-Newtonian fluid model together. The clearance space of the finite bearing has been determined by the finite element method adopting Galerkin’s procedure and robust iteration technique. The cylindrical coordinate forms of momentum and continuity equations are used for the flow field of the finite bearing assuming the turbulent regime and non-Newtonian lubricant. Dynamic performance parameters of a finite bearing have been computed regarding direct and cross-coupled fluid-film coefficients, equivalent stiffness coefficient, whirl ratio, and critical mass at different eccentricity ratios for distinct values of Reynolds numbers preferably up to 13,300 and varied values of non-linear factor of the non-Newtonian fluid model. The obtained results revealed the performance enhancement in the combined regime as compared to pure turbulence and non-Newtonian flow conditions. The stability of finite bearing is significantly improved under the proposed severe flow regime.

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Linear Stability Analysis of Journal Bearings Lubricated With a Non-Newtonian Rabinowitsch Fluid

Cited by 9 publications

References 8 publications

Threshold speed of short journal bearings considering the non-Gaussian longitudinal surface roughness

Threshold speed of short journal bearings considering the non-Gaussian longitudinal surface roughness

Discussion on dynamic characteristics of long journal bearings considering surface roughness

Performance of finite bearing under the combined influence of turbulent and non-Newtonian lubrication

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