Optimal design of FDBs of a HDD to minimize friction torque

Abstract

This research proposes a method to optimize FDBs (Fluid Dynamic Bearings) of a HDD in such a way to minimize friction torque utilizing the stability analysis. The objective function is defined as the friction torque of FDBs. It is calculated by integrating the shear stress which is determined from the Reynolds equation by FEM. One of the important constraints is to keep the same critical mass in order to maintain the same level of dynamic performance of the rotating disk-spindle system. The critical mass is determined from the stability analysis of a rotating disk-spindle system. Stiffness and damping coefficients are calculated from the perturbed Reynolds equation by FEM. Design variables are the width, clearance, groove angle, groove depth, and groove to ridge ratio of journal bearings. Micro genetic algorithm is applied to solve the proposed optimal problem, and it shows that the optimal design of the FDBs decreases the friction torque of a conventional design by 7%.