Hard disk drives function perfectly satisfactorily when used in a stable
environment, but in certain applications they are subjected to shock and vibration.
During the work reported in this thesis it has been found that when typical hard disk
drives are subjected lo vibration, data transfer failure is found to be significant at
frequencies between 440Hz and 700Hz, at an extreme, failing at only Ig of sinusoidal
vibration. These failures can largely be attributed to two key components: the
suspension arm and the hard disk. At non-critical frequencies of vibration the typical
hard disk drive can reliably transfer data whilst subjected to as much as 45g.
When transferring data to the drive controller, the drive's operations are
controlled and monitored using BIOS commands. Examining the embedded error
signals proved that the drive predominantly failed due lo tracking errors.
Novel piezo-electric sensors have been developed to measure unobtrusively
suspension arm and disk motion, the results from which show the disk to be the most
significant failure mechanism, with its First mode of resonance at around 440Hz. The
suspension arm movement has been found to be greatest at IkHz.
Extensive modelling of the flexure of the disk, clamped and unclamped, has
been undertaken using finite element analysis. The theoretical modelling strongly
reinforces the empirical results presented in this thesis.
If suspension arm movement is not directly coupled with disk movement then
a flying height variation is created. This, together with tracking variations, leads to
data transfer corruption. This has been found to occur at IkHz and 2kHz.
An optical system has been developed and characterised for a novel and
inexpensive flying height measurement system using compact disc player technology
