Shock dynamic characteristics of hard disk drives

Abstract

The interest in the effects of shock on hard disk drives (HDDs) has come into currency due to the increasingly hostile environments encountered in the usage of the portable computer as well as the application of HDDs in consumer devices. Their mechanical robustness under shock and other mechanical disturbances is of great concern. Shock dynamic characteristics of HDDs are investigated in this dissertation using numerical, analytical, and experimental techniques. Firstly, the influence of the pulse widthlduration and the pulse amplitude of single half-sine acceleration pulse on shock responses of the relative displacement of a head actuator assembly (HAA) was investigated by using FEM simulation and a singledegree-of-freedom (SDOF) model. For both the FEM and SDOF models, the peak relative displacement occurs at a critical frequency ratio (i.e. P = w l w , x 0.6). In other words, apseudo resonance phenomenon occurs at the critical frequency ratio. Secondly, to investigate the pulse shape effects of acceleration pulse on shock responses, the HAA subjected to three pulse shapes of acceleration shock was analyzed by using finite element simulation. An abnormal phenomenon was observed in the shock responses where a higher energy pulse results in lower responses. This has been explained in terms of a power spectrum analysis.