Topology Designs of Slider Air Bearings

Abstract

A new approach for topology designs of slider air bearings in magnetic recording disk drives is suggested by using large-scale discrete variable optimization techniques. Conventional optimization techniques are restricted to the original topology of the slider by modifying the initial designs. To overcome the restriction, a new topology design approach is presented with enhanced mathematical techniques. Topology optimization of slider air bearings typically has a large number of design variables because the finite mesh must be fine enough to represent the shape of the air bearing surface (ABS). To handle a large number of design variables, an efficient strategy for the optimization including the sensitivity analysis must be established. As a gradient-based local optimization algorithm, the sequential unconstrained minimization technique (SUMT) using an exterior penalty function is used, which requires little computational effort and computer memory. For the gradient calculation, the analytical design sensitivity analysis method introducing an adjoint variable is employed. A topology design problem is formulated as a function of the residuals which is calculated by solving the generalized Reynolds equation. A very large number of discrete design variables (=9409) are dealt with, which denote the rail heights at grid cells. To validate the suggested design methodology, a developed program is applied to two slider models with one and three trailing rails. The simulation results demonstrated the effectiveness of the proposed design methodology by showing that the optimized topologies have reasonable shapes without any initial designs.