The purpose of this paper is to present the linearized stability analysis of two-layered fluid film in the journal bearing. In this work, a modified classical Reynolds equation is derived under dynamic conditions consisting of two layers of fluid film described by Newtonian viscosities. The magnitude of lubricant layer’s film thickness and viscosities are taken into consideration. The Reynolds boundary conditions are used in the analysis of classical one-dimensional journal bearing to predict the stiffness and damping coefficients, threshold speed and critical whirl frequency ratio. The coefficients of load capacity, threshold speed, and critical whirl frequency ratio (Cw, $Cω$, $CΩ$) for two-layered film with reference to homogeneous film are computed as a function of the two parameters: (i) higher to lower dynamic viscosity ratio of two-layered fluid film ($β$), and (ii) thickness ratio of fluid layer attached to journal and bearing ($γ$). Higher threshold speed is obtained for thick high viscosity fluid film attached to the bearing surface and a thin low viscosity fluid film attached to the journal surface.

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