Modal testing and finite element modelling of subsystem in hard disk drive

Residual vibration is one of the primary mechanical problems that affect the dynamic characteristics of the head actuator assembly in hard disk drives, and the data access speed and positioning resolution. This paper presents the experimental modal testing and finite element modelling that are tailored to vibration testing in the head actuator assembly. The special excitation method has been applied for modal testing of the head actuator assembly, based on voice coil motor without altering the modal property of the structure in actual operating condition. The finite element models of the head actuator assembly have been developed, and various modes have been analysed. It is shown that the dynamic characteristics of the head actuator assembly are very complicated, in particular the vibration due to the lateral quasi-rigid body mode caused by the flexibility of the pivot, and mass and structure of the head actuator arm. It is thus essential to develop effective approaches to reduce the vibration of the lateral quasi-rigid mode and improve the dynamic characteristics of the head actuator assembly, so that high-performance HDD can be developed.