Hard disk interface used in computer forensic science

Author(s):  
C. Wick ◽  
S. Avramov-Zamurovic ◽  
J. Lyle
2014 ◽  
Vol 136 (4) ◽  
Author(s):  
James White

Increased storage capacity and decreased power consumption are two key motivations in the development of hard disk drive (HDD) storage products. Two ideas that address these areas have recently received attention in the literature. These are (1) the use of helium instead of air as the working gas in the drive and (2) the incorporation of a thin metal foil as the disk substrate, replacing the much thicker aluminum or glass substrate of the hard disk (HD). The work that has been previously reported considered either the use of helium or thin foil substrates, but not both. This paper does consider both. It reports dynamic gas bearing simulation results for the helium filled interface between opposed recording heads and a disk whose substrate is a thin titanium foil. Motivation for the selection of titanium as the foil material is described in the paper. The thickness of the foil is chosen so as to achieve an optimal combination of centrifugal force and bending force that will provide required disk flatness and stability during high-speed rotation. Large-scale dynamic simulation is used to track the response of the recording head slider-foil disk interface due to mechanical shock in the vertical, pitch, and roll directions. Results are described and compared with those of the configuration that includes helium and a HD. Attention is focused on response to off-design conditions that can create head crash with the HD.


Author(s):  
Eric M. Jayson ◽  
Frank E. Talke

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head/disk interface after a shock as a function of the design of the air bearing contour.


Author(s):  
Kyaw Sett Myo ◽  
Weidong Zhou ◽  
Xiaoyang Huang ◽  
Shengkai Yu

Heat-assisted magnetic recording (HAMR) is one of prospective high density recording technologies in current hard disk industry. It requires heating a spot on the recording media with the laser beam to overcome the superpara-magnetic limit. The heat produced by laser beam causes the temperature field on the hard disk surface to be highly non-uniform, which may lead to unexpectedly severe lubricant loss, or even the failure of the whole HAMR system. In the meantime, the heat loss caused by the optical delivery system may cause unwanted thermal protrusion on the slider body, which may affect slider’s flying stability in the end.


2011 ◽  
Vol 287-290 ◽  
pp. 2339-2342
Author(s):  
Hong Rui Ao ◽  
Deng Pan ◽  
Hong Yuan Jiang

The contact at head/disk interface in hard disk drives subject to an external shock has been studied using the finite element method. A rigid cylinder moving over a two-layered thin film was implemented to simulate the contact between the recording slider and the disk. The effects of different friction coefficients on the von Mises stress of two-layered thin film were investigated. The relation between pressed depth and width of deformation has been obtained. Results show that the amplitude decreases with increase of friction coefficient while the period of slider motion is diminution. In addition, the stress distribution fits Hertzian contact theory.


Author(s):  
Rohit P. Ambekar ◽  
David B. Bogy

The touchdown-takeoff velocity hysteresis observed in hard disk drives during CSS or L/UL tests is analyzed using an experimental approach. Tests similar to L/UL were conducted for different slider-disk combinations at different humidities. Factors affecting the touchdown and takeoff velocity were identified on the basis of their domain of operation. It is concluded that the intermolecular forces and meniscus forces are contributing factors to hysteresis, which is also influenced by disk topography and slider dynamics.


Author(s):  
Rahul Rai ◽  
David B. Bogy

With the introduction of netbook computers two years ago, the demand for hard disk drives (HDD) for mobile applications has greatly increased. High shock resistance is an important requirement for the reliable performance of HDDs in such applications. In this paper we conduct a numerical investigation to understand the failure mechanism of the head disk interface (HDI) during an operational shock. Simulation results suggest that the excitation frequency spectrum has a strong influence on HDI failure. We also investigate the effect of the parking or load unload (LUL) ramp on shock resistance using a new spinning disk model. The results suggest that asymmetric excitations induced by ramp-disk collision causes failure of the HDI at lower shock magnitudes. This study can be helpful in improving the design of HDD components and air bearing sliders (ABS) for better shock performance.


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