Analysis of a Self-Acting Air Journal Bearing: Effect of Dynamic Deformation of Bump Foil

A theoretical investigation on the effects of both
steady-state and dynamic deformations of the foils on the dynamic
performance characteristics of a self-acting air foil journal bearing
operating under small harmonic vibrations is proposed. To take into
account the dynamic deformations of foils, the perturbation method is
used for determining the gas-film stiffness and damping coefficients
for given values of excitation frequency, compressibility number, and
compliance factor of the bump foil. The nonlinear stationary
Reynolds’ equation is solved by means of the Galerkins’ finite
element formulation while the finite differences method are used to
solve the first order complex dynamic equations resulting from the
perturbation of the nonlinear transient compressible Reynolds’
equation. The stiffness of a bump is uniformly distributed throughout
the bearing surface (generation I bearing). It was found that the
dynamic properties of the compliant finite length journal bearing are
significantly affected by the compliance of foils especially whenthe
dynamic deformation of foils is considered in addition to the static
one by applying the principle of superposition.

• H. Bensouilah
• H. Boucherit
• M. Lahmar

• Elasto-aerodynamic lubrication
• Air foil bearing
• Steady-state deformation
• Dynamic deformation
• Stiffness and damping coefficients
• Perturbation method
• Fluid-structure interaction
• Galerk infinite element method
• Finite difference method.

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