Modeling and controlling flow-induced suspension-head unit vibrations in hard disk drives

Abstract

The problem of flow-induced vibrations of suspension-head units (SHUs) in hard disk drives is investigated numerically. Attention is focused on the simplest geometrical and dynamical conditions that retain the physics essential to SHUs in real drives. Conservation equations are solved for the constant property, two-dimensional, unsteady flow of air past a pair of prisms contained in a channel with sliding walls. Each prism simulates the suspension section of a SHU. The prisms face each other symmetrically and are aligned parallel to the sliding channel walls, normal to their direction of motion. The sliding channel walls simulate the rotating disks in a drive. The flow fields obtained are used to calculate SHU vibration frequencies. For this, the suspension section of a SHU is approximated as an Euler–Bernoulli beam (linear motion) of constant height2mmwidth.2mmheight.2mmwidth5mmheight2mmwidth.2mm-shaped cross-section (henceforth denoted as “U-shaped”) with a point mass, representing the magnetic head, located at its tip. The beam is assumed to be very stiff, meaning that movements near the design point (away from resonances) are small. This allows reliable solutions to be obtained by treating the flow as being unaffected by the miniscule motions of the suspensions, whereas the suspensions are fully affected by the unsteadiness imparted to them by the flow. SHU vibration characteristics have been determined relative to the flow fields that induce them for a variety of conditions. The paper discusses a subset of these for a flow at 50 m/s as well as the possible adaptation of interactive computational-experimental methodologies (ICEME) to minimize and/or control flow-induced vibrations of SHUs in hard drives.