Limiting Load Capacity and Stiffness Coefficients of Bump Recess Foil Journal Bearing with FGM

The bump-recess configuration with top foil of air foil journal bearing is analyzed using Functionally Graded Material (FGM). The purpose of the study is to examine journal bearing’s limiting load capacity and coefficients of limiting stiffness. Different top foil texture bump patterns are examined. A journal (foil) bearing's limiting load capacity and limiting stiffness coefficients are explored in relation to the extent and height of the top foil texture bump.

The methods presented are based on an analytical model for limiting load capacity and limiting stiffness coefficients of the bump-recess configuration on top foil of air foil journal bearing using FGM. A simplified version of the compressible Reynolds equation is considered to estimate the limiting load capacity and limiting stiffness coefficients. These estimates are made for higher bearing numbers coupled with higher speeds for the journal foil bearing. The theoretical model accounts for the bump-recess configuration with FGM and bump foil compliance. The top foil bearing's limiting pressure gradient solution is examined with a texture bump.

The results of the limiting load capacity and limiting coefficients of stiffness of bump-type journal foil bearings with FGM are compared for different bump-recess heights. A functionally graded (FG) sub-foil with an extended bump texture top foil varies the cross-coupled non-dimensional stiffness coefficients considerably with increasing nondimensional bump texture height.

Enhanced bump texture on the top foil improves limiting load capacity and coefficients of limiting stiffness properties of bump-type journal foil bearings with FGM.