The pulse width effect on the shock response of the hard disk drive

A finite element model (FEM) of the ST drive from Seagate is developed in ANSYS to investigate the shock response of the hard disk drive (HDD). The FEM includes the pivot bearing, the head stack assembly (HSA) and the disk. The free state of the HSA is determined by an iterative procedure to produce the prescribed preloading force at the head–disk interface. The FE model is then verified by conducting a modal analysis over the HSA. The obtained mode shapes and resonant frequencies are compared with the modal testing results. An acceleration pulse is applied to the shaft and the whole disk surface at the same time to study the shock response of the HDD. The head slap behavior is examined at the slider–disk interface. The effect of the pulse width on the head slap behavior is studied. The duration of the acceleration pulse varies from 0.3 to 1 ms. It is found that the lift-up height of the slider reaches a peak value at different pulse widths when the amplitude of acceleration pulse changes. This is due to the nonlinear behavior introduced by the contact surfaces.