| This dissertation is concerned with the head-disk interface in magnetic recording hard disk drive systems, the most critical element in achieving increases in storage density. In particular, the possible use of dynamic load-unload is investigated as an alternative to the widely used contact-start-stop method. Dynamic load-unload is the process of loading and unloading the air bearing slider that carries the read/write head to and from a disk that is rotating at speeds sufficiently high to support an air bearing. The primary concerns are slider-disk impacts that may occur during the load-unload process and the possible damage that these impacts may inflict on the slider and/or disk. First experimental techniques for detecting such contacts are developed. Then load-unload experiments are carried out and finally numerical simulations of these processes are undertaken.; Since impacts cause elastic bodies to ring in free vibration, natural frequencies of the various transducers and sliders are studied by use of finite element modeling and experimentation. It is determined that the lowest natural frequency of a mini-Winchester slider is around 130 kHz, whereas it is about 310 kHz in the two rail 3370 and 3380 sliders.; Laser Doppler vibrometer (LDV) and acoustic emission (AE) are used to investigate the slider dynamics and detection of possible slider-disk contacts during dynamic load-unload. The electrical resistance method is also applied to the detection of slider-disk contacts during the contact-start-stop and dynamic load-unload processes.; A two-beam LDV system and AE are employed to investigate the effects of the initial pitch and roll, the initial height, and the control loading speed. Based on the experimental results, several slider-disk contact criteria are proposed.; In numerical simulation, the effects of the slider's loading velocity, disk runout, loading location on the disk, and initial pitch and roll on the slider dynamics and slider-disk contacts during dynamic loading are studied. Slider-disk contact criteria are obtained from the numerical simulation, and compared with those obtained by experiments. |
