Direct Comparison of Computational and Experimental Head-Slap Data for a Nonoperating Hard Disk Drive

We refined a previously developed finite-element (FE) model of a Seagate Bali II hard-disk drive (HDD) to include compliance contributed by roller bearings at the spindle and pivot motors. We then performed drop-test simulations with the nonlinear structural dynamic codes LS-DYNA and ABAQUS/Explicit. In parallel, we subjected a nonoperating Bali II HDD to physical tilt-drop tests from drop angles of 10deg and 45deg, representing a mild and a substantial shock input, respectively. We measured velocity responses with a laser Doppler vibrometer (LDV) at two points on the HDD. The first point was on the topmost read/write head at the center of its trailing edge, and the second point was on the top surface of the baseplate directly above the line of contact with the impact bar. In the FE studies, the baseplate velocity histories measured during the tests were used to prescribe input motions at the corresponding baseplate nodes. We compared computed and measured head velocity histories in order to evaluate the effectiveness of present state-of-the-art simulation tools for modeling head-slap events