Numerical Study on the Effects of Linear Protrusion on Flow-Induced Carriage Excitation Force in Hard Disk Drives

The positioning accuracy of magnetic heads need to be improved to increase the recording capacity of hard disk drives. In our previous study, the experimental results confirmed that the head positioning error could be decreased by attaching linear protrusions on the leading edge of the carriage arms. However, the mechanism underlying the phenomenon has not been elucidated. In the current research, we evaluated the effect of leading-edge protrusions on the flow-induced carriage excitation force using the finite element (FE) method analysis and the Hilbert-Huang transform (HHT). We prepared two carriage-arm FE models, with and without linear protrusions, on the leading edges of the arm, and performed the FE analyses. Subsequently, we conducted a frequency analysis by applying the HHT to the simulated torque-disturbance time series of each FE model and the results were later compared. Our results show that the leading-edge protrusions were found to decrease the mean velocity between the arm and the disk, thereby decreasing the vorticity fluctuation in the arm hole, and to decrease the fluctuations in pressure on the outer sidewall of the carriage arm around the coil support.