Vibro-acoustic analysis of hard disk drives

Hard disk drives (HDD) rotating at high speeds cause noise and vibration problems. At high speed, one dominant noise source is structure borne noise produced from structural vibration. In this paper, the governing equations of motion for a HDD spindle system subjected to the motor torque pulsations are derived through the use of the Lagrange equation. A vibro-acoustic model of a high speed HDD has been developed by combining source, radiator and path models to yield the radiated sound power spectrum associated with the pulsating motor torque. The radiated sound of the casing due to the pulsations is calculated. The geometric coupling between disk modes and the acoustic medium should be well understood in order to predict which disk modes are radiating and which modes are not radiating.