Study on angular displacement characteristics on topological optimum design problem of hydrodynamic thrust air bearing

Abstract

The purpose of this research is to find the optimum groove geometry to enhance the stiffness against the axial and angular direction of thrust bearing simultaneously. In order to fulfill the requirement of miniaturization and thinning of many devices, the topological optimization is conducted to maximize the axial and angular stiffness of thrust air bearing. Applying the boundary fitted coordinate system and spline interpolation function make it possible to change the shape of bearing groove freely, and then the static and dynamic characteristics of the bearings are calculated numerically by using the divergence formulation method. The spring and damping coefficients against the axial and angular fluctuations are obtained by applying the assumption of the micro vibration of bearing clearance and pressure to the numerical method. Based on the numerical calculation method, topological optimization is conducted. As a result, a new groove shape having two curved portions is obtained. In case of the optimized bearing, positive pressure in the outer circumference on the bearing surface and negative pressure in the inner circumference are simultaneously generated. Comparing the maximum pressure, it was found that the optimized bearing is superior to spiral-grooved bearing. Moreover, drastically improvements in the axial and angular stiffness of the optimized bearing are shown.