Misalignment effects on steady‐state and dynamic behaviour of compliant journal bearings lubricated with couple stress fluids

Boucherit, Hamid; Lahmar, Mustapha; Bou‐Saïd, Benyebka

doi:10.1002/ls.65

Cited by 25 publications

(25 citation statements)

References 18 publications

(15 reference statements)

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“…Assuming that small harmonic whirling of the journal within the bearing with frequency υ * , we can express the instantaneous position of the journal center as

ε = ε_{0} + ε_{1} e^{italiciγ \overset{t}{true}} and ϕ = ϕ_{0} + ϕ_{1} e^{italiciγ \overset{t}{true}}, i = \sqrt{- 1},

where ε 0 and φ 0 are the eccentricity ratio and attitude angle of the journal center at static equilibrium position, respectively, and ε 1 and φ 1 are the amplitudes of eccentricity ratio and attitude angle in dynamic motion, respectively. The parameter γ = υ * / ω is the excitation frequency ratio.…”

Section: Hydrodynamic Lubrication Equations By Contaminated Lubricantsmentioning

confidence: 99%

“…The displacement field at the fluid film bearing liner interface due to pressure forces is determined using the elastic thin layer model (Winkler model). Compared to the finite element method, the main advantage of this elasticity model is its low‐computational time, the elastic deformations being only dependent on the local pressure . The nonlinear fluid‐structure interaction problem is solved numerically by means of an iterative procedure.…”

Section: Introductionmentioning

confidence: 99%

“…Compared to the finite element method, the main advantage of this elasticity model is its low-computational time, the elastic deformations being only dependent on the local pressure. 24 The nonlinear fluid-structure interaction problem is solved numerically by means of an iterative procedure.…”

Section: Introductionmentioning

confidence: 99%

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The effect solid particle lubricant contamination on the dynamic behavior of compliant journal bearings

Boucherit

Bou‐Saïd²,

Lahmar

2017

Lubrication Science

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The proposed work concerns a theoretical and numerical investigation of the effect of solid particle contamination of lubricant oils on the static and dynamic characteristics of a finite length compliant journal bearing operating under isothermal conditions with laminar flow. In the present investigation, we use simple models based on the Einstein's mixture theory, which is characterized by the presence of suspended rigid particles in a fluid. Using the classical assumptions of lubrication, a Reynolds equation is derived and solved numerically by the finite difference method. The displacement field at the fluid film bearing liner interface due to pressure forces is determined using the elastic thin layer model. The results obtained show that the presence of suspended rigid particles in the lubricating oil (solid contamination) has significant effects on the hydrodynamic performance characteristics such as the pressure field, friction force, flow rate, elastic surface deformation as well as stability maps of the rotor‐bearing system (critical mass and whirl frequency) especially at high volumetric concentration.

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“…Assuming that small harmonic whirling of the journal within the bearing with frequency υ * , we can express the instantaneous position of the journal center as

ε = ε_{0} + ε_{1} e^{italiciγ \overset{t}{true}} and ϕ = ϕ_{0} + ϕ_{1} e^{italiciγ \overset{t}{true}}, i = \sqrt{- 1},

Section: Hydrodynamic Lubrication Equations By Contaminated Lubricantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effect solid particle lubricant contamination on the dynamic behavior of compliant journal bearings

Boucherit

Bou‐Saïd²,

Lahmar

2017

Lubrication Science

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“…For smooth surface compliant layer, the normal surface elastic compression δ s on a layer with a small thickness d compared with length of contact L can be related to the local pressure expressed p s according to the Winkler model by the following expression:

δ_{s} = C_{s} p_{s} = \frac{d}{E} (\frac{((), 1 + ν) ((), 1 - 2 ν)}{(1 - ν)}) p_{s}

where E , ν and p s are the Young's modulus, the Poisson ratio and the pressure distribution of the stationary smooth surface, respectively. This model was validated by Boucherit et al . for small thickness bearing liner using three‐dimensional finite element method in the case of compliant finite length journal bearing.…”

Section: Problem Definition and Basic Equationsmentioning

confidence: 99%

“…where E, ν and p s are the Young's modulus, the Poisson ratio and the pressure distribution of the stationary smooth surface, respectively. This model was validated by Boucherit et al 18 for small thickness bearing liner using three-dimensional finite element method in the case of compliant finite length journal bearing. It is less time consuming as no computation is needed to obtain the elastic deformation.…”

Section: Couple Stress and Surface Roughness Effects On Ehl Contactmentioning

confidence: 99%

Coupled couple stress and surface roughness effects on elasto-hydrodynamic contact

et al. 2013

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This paper deals with the combined effects of couple stress and surface roughness to inspect the elasto‐hydrodynamic performance of slider bearing systems. On the basis of the couple stress Stokes theory and homogenisation method, the homogenised generalised Reynolds equation including the slider bearing stationary surface deformation is derived. The total deformation include the deformation of smooth surface, taken into account by the elastic thin layer model, and the deformation of roughness corresponding to a sinusoidal normal displacement on an elastic half space of identical wavelength. The governing equations are discretised by the finite difference method, and the obtained algebraic equations are solved using the iterative overrelaxation Gauss–Seidel technique. The load‐carrying capacity and friction coefficient are presented for transverse, longitudinal and anisotropic roughness patterns for different values of the couple stress parameter in both rigid and deformable cases. The simulation results indicate that the interaction between couple stress, surface roughness and elastic deformation effects is significant. Copyright © 2013 John Wiley & Sons, Ltd.

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Analysis of couple‐stress effects in gas foil bearings using the V. K. Stokes micro‐continuum theory

Laouadi

Lahmar

Bou‐Saïd

et al. 2018

Lubrication Science

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This paper presents an original theoretical investigation of the steady‐state and dynamic characteristics of foil journal bearings lubricated with contaminated air taking into account couple stresses because of the presence of pollutant substances. The substance can be solid particles (eg dust, ash, pollen, and smoke). In aerodynamic lubrication theory, a fluid with couple stresses so‐called couple stress or polar fluid may be considered as one characterised by the 2 physical constants μ and η, which are the absolute viscosity assumed to be independent of the particle volume fraction and the new material constant responsible for couple stress or polar property. The effects of couple stresses on the oil‐lubricated sliding bearings are usually studied by defining the parameter 0.25eml=η/μ12 or its normalised form truel~=l/C . The couple‐stress parameter l, which has the dimension of length, can be thought of as a fluid property depending on the size of the particle contained in the base fluid (solvent). To determine the aerodynamic pressure and the power loss, the governing modified Reynolds' equation and the viscous dissipation term appearing on the right‐hand side of the modified energy equation are derived by using the Vijay Kumar Stokes micro‐continuum theory. The system of partial differential equations resulting from analytical perturbation of the transient modified Reynolds' equation is solved for the steady‐state and dynamic pressures by means of the finite difference method considering both the static and dynamic deformations of the bump foil. Using the complex variable technique, the analytical perturbation process leads to 2 first‐order uncoupled partial differential equations instead of 4 coupled equations as it is usually found in the technical literature. On the other hand, the 2 Cartesian coordinates of the equilibrium position for a given applied static load are iteratively determined by solving the nonlinear equilibrium equations of the journal bearing system with the improved Newton‐Raphson method. According to the obtained results, the effects of couple stresses on the steady‐state and dynamic behaviour of foil self‐acting gas bearings are significant and cannot be overlooked. The results also show that the dynamic deformation of the bump foil should be included in calculating the dynamic performance characteristics of foil journal bearings.

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Misalignment effects on steady‐state and dynamic behaviour of compliant journal bearings lubricated with couple stress fluids

Cited by 25 publications

References 18 publications

The effect solid particle lubricant contamination on the dynamic behavior of compliant journal bearings

The effect solid particle lubricant contamination on the dynamic behavior of compliant journal bearings

Coupled couple stress and surface roughness effects on elasto-hydrodynamic contact

Analysis of couple‐stress effects in gas foil bearings using the V. K. Stokes micro‐continuum theory

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