Numerical Simulation of Operational-Shock in Small Form Factor Hard Disk Drives

Abstract

As nontraditional applications of hard disk drives emerge, their mechanical robustness during the operating state is of greater concern. Over the past few years, there has been an increasing application of small form factor (1in. and smaller) hard disk drives in portable consumer appliances and gadgets. A procedure for simulating the operational shock response of a disk-suspension-slider air bearing system is proposed in this paper. A coupled structural-fluid model is presented which can be used to obtain the dynamic response of the slider-suspension-disk system. A commercial program, ANSYS, is used for the finite element models of the suspension and the disk, while the CML dynamic air bearing code is used to concurrently solve the air bearing equations of the system. We obtain not only the responses of the structural components, but also the responses of the air bearing slider. The procedure is convenient for practical application as well as being highly accurate, since it implicitly solves the structural and air bearing problems simultaneously. It is used to simulate the shock response of a 1in. drive. The air bearing has different responses for upward and downward shocks (which are referred to as positive and negative shocks, respectively). For negative shocks, slider-disk contacts are observed to occur when a strong shock is applied, however, the air bearing does not collapse. For positive shocks, we observe a collapse of the air bearing when the shock is sufficiently strong, which is followed by severe contacts between the slider and the disk due to the “head-slap” phenomenon.