A linear analysis of conical whirl instability of an unloaded rigid rotor supported on hydrodynamic journal bearings with micropolar lubrication has been presented. In self-excited conical whirling motion, the rotor has 2 degrees of freedom with hydrdynamic film pressure distribution in the bearing clearance. The hydrodynamic film pressure distribution has been obtained by solving the modified Reynolds equation based on the theory of the micropolar lubrication satisfying the appropriate boundary conditions. With the help of the components of dynamic tilting stiffness and damping coefficients, stability characteristics are obtained. The effects of various parameters, namely the non-dimensional micropolar characteristic length, coupling number, clearance ratio and slenderness ratio on the conical stability parameter have been investigated.
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