A simple analytical model for an elastohydrostatic thrust bearing

A new design of an elastohydrostatic bearing with a structurally elastic pad is theoretically analyzed. A single recess circular thrust bearing has the upper pad provided with a large cavity, covered with an elastic metallic membrane. The latter deflects under the pressure distribution in the bearing, creating a radial convergent gap. A simplified axi-symmetric analytical model based on two assumptions is proposed: (i) parabolic approximation for the elastic component of the film thickness and (ii) the maximum elastic deformation of the membrane is calculated analytically using a simplified linear pressure variation in radial direction on the land. Thus, the coupled equations for fluid film and elastic deformation can be solved successively and the bearing performance characteristics can be easily calculated. A parametric analysis, function of a complex elastic parameter and relative recess radius was performed, showing higher load capacity and lower friction similarly to what was previously obtained using rubber-based compliant bearings. A first stage of validation of the analytical model consisted in using a structural finite element model. For the sake of simplicity, the pressure distribution was written in an APDL code using the ANSYS program. The comparison showed small differences for typical values of the recess radius.