Frequency analysis of internal flow of hard disk drives using Hilbert-Huang Transform

Abstract

In this study, we applied the Hilbert-Huang transform (HHT) to the time series of the torque exerted on the carriage arm, which is calculated using finite element analysis. Then, a frequency analysis using FFT was conducted and compared with the HHT results. Comparing the both spectra, the results confirmed that, in the Fourier spectra, the energy of the non-stationary phenomenon, whose frequency and amplitude are fluctuating at a specific frequency, diffuses over a wide frequency-band, and that forms the broadly expanded spectra, especially at low frequencies. Therefore, it is necessary for more precise head positioning to decrease torque-fluctuations due to non-stationary phenomena, such as a vortex shedding around an arm, which are not always observed in the power spectrum obtained by the FFT analysis.