The Effect of Diamondlike Carbon Overcoat on the Tribological Performance of the Dimple/Gimbal Interface in Hard Disk Drives1

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Youyi Fu ◽  
Vlado A. Lubarda ◽  
Frank E. Talke
Keyword(s):  
Stainless Steel ◽  
Principal Stress ◽  
Elastic Moduli ◽  
Crack Formation ◽  
Hard Disk ◽  
Disk Drive ◽  
Maximum Principal Stress ◽  
Fretting Wear ◽  
Carbon Overcoat ◽  
Diamondlike Carbon

Fretting wear at the dimple/gimbal interface of a hard disk drive suspension was investigated for stainless steel dimples in contact with stainless steel gimbals coated with diamondlike carbon (DLC) of different thicknesses and different elastic moduli. Scanning electron microscopy (SEM) was used to evaluate the size and characteristics of the wear scar of both the dimple and the gimbal. Fretting wear and fatigue-type cracks were found predominantly on the dimple. For different dimple/gimbal combinations tested in this study, the least amount of wear was obtained for the case of a 690 nm thick DLC overcoat. Numerical simulations were performed to calculate the maximum principal stress in the dimple and the gimbal with the goal of correlating wear and the maximum principal stress. The maximum principal stress in both the dimple and the gimbal was found to increase with an increase of the elastic modulus of the DLC overcoat on the gimbal. On comparing the experimental and simulation results, we conclude that wear and fatigue crack formation can be explained by the different level of the maximum principal stress in both the dimple and the gimbal.

scholarly journals Crack formation during solid pyrolysis: evolution, pattern formation and statistical behaviour

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190211 ◽  
Author(s):  
Yen T. Nguyen ◽  
Thomas J. Pence ◽  
Indrek S. Wichman
Keyword(s):  
Crack Initiation ◽  
Crack Length ◽  
Principal Stress ◽  
Crack Formation ◽  
Structural Integrity ◽  
Degradation Process ◽  
Maximum Principal Stress ◽  
Evolution Pattern ◽  
Average Crack ◽  
Forming Defects

As solids pyrolyse during combustion, they lose chemical and structural integrity by gradually degrading into residual char and forming defects such as voids, fissures and cracks. The material degradation process, which is coupled to the crack formation process, is described using a theoretical model and is numerically simulated using the finite-element method for a generic, charring, rubber-like material. In this model, a slab of material is subjected to an external, localized heat flux and, as the material degrades, cracks form when the local principal stress exceeds a defined cracking threshold. The magnitude of the cracking threshold σ c is systematically varied in order to examine its influences on crack initiation, evolution, distribution and behaviour over time. When σ c exceeds the maximum principal stress for the entire process, σ m , then no cracks are generated. We quantify how the average crack spacing, total crack length and crack initiation time depend upon the ratio σ c / σ m . Two characteristic domains of crack formation behaviour are identified from the crack initiation behaviour. Correlations are produced for the crack length evolution and final crack length values as functions of σ c / σ m . Crack intersection patterns and behaviour are described and characterized.

scholarly journals The Separation of Aluminum and Stainless-Steel Scraps Using Vibrating Mixed-Size Ball Bed

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 868
Author(s):  
Hyunjin Na ◽  
Kyoungkeun Yoo ◽  
Manis Kumar Jha ◽  
Carlito Baltazar Tabelin
Keyword(s):  
Stainless Steel ◽  
Hard Disk Drive ◽  
Vibration Amplitude ◽  
Separation Efficiency ◽  
Hard Disk ◽  
Disk Drive ◽  
Gravity Separation ◽  
Separation Method ◽  
Vibration Test ◽  
Dramatic Improvement

Dry gravity separation using a vibrating zirconia ball bed is proposed in this study to separate aluminum (Al) and stainless steel (STS) scraps obtained from spent hard disk drive recycling. The effects of zirconia ball sizes and vibrating power (vibration amplitude) on the separation efficiency of Al and STS scraps were investigated. The zirconia balls moved down at the center of the vessel and rose with the wall during the vibration test. Although more STS scraps sunk than Al scraps did, the separation efficiency was not maintained because Al scraps also sunk along with balls’ movement. The separation efficiency increased to 86.6% using 1-mm zirconia balls with a 2.5-mm vibration amplitude at 4 min, but it decreased rapidly by ball moving. Therefore, when a ball bed of mixed sizes (2:1 ratio of 1 and 3 mm) was used and arranged, whereby the 3-mm zirconia balls were above the 1-mm ball bed, the separation efficiency increased to 100% for more than 2 min. This dramatic improvement was because the 3-mm ball bed acted as a barrier to prevent sunken STS scraps from rising, and Al scrap cannot sink through the 3-mm ball bed. These results indicate that the separation of Al and STS scraps could be achieved successfully using the dry gravity separation method.

Investigation of fretting wear at the dimple/gimbal interface in a hard disk drive suspension

Wear ◽  
2010 ◽  
Vol 268 (11-12) ◽  
pp. 1347-1353 ◽  
Author(s):  
B. Raeymaekers ◽  
S. Helm ◽  
R. Brunner ◽  
E.B. Fanslau ◽  
F.E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Fretting Wear

scholarly journals Design and Analysis of Balloon-expandable Stainless Steel Coronary Stent

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Xiaolin Pan ◽  
Gengqiang Shi ◽  
Yuan Li ◽  
Shanshan Wu ◽  
Long Chen
Keyword(s):  
Stainless Steel ◽  
Blood Flow ◽  
Shear Stress ◽  
Principal Stress ◽  
Vessel Wall ◽  
Maximum Principal Stress ◽  
Coronary Stent ◽  
Volume Control ◽  
Ansys Simulation ◽  
Implantation Process

<p>This thesis uses “Volume Control” ballon-stent model, and according to results of deformation of a stent and vascular during implantation, we obtain the stress contours of the stent during implantation. The results conclude by ANSYS simulation show that during the implantation process, expansion of balloon body will make the narrow part of the blood wall fragment tough. After placement of the stent, due to blood flow in vessel makes that the inner wall of blood vessels has uneven distribution of shear stress; And, in the vicinity of the stent structure, it has a lower <sup>[7]</sup><sup> </sup>shear stress to vessel wall. During the expansion of the stent, the maximum principal stress concentrate on the connection between coronary stent itself and stiffeners.</p>

Hard disk drive failure prediction using SMART attribute

2021 ◽  
Author(s):  
Vikas Tomer ◽  
Vedna Sharma ◽  
Sonali Gupta ◽  
Devesh Pratap Singh
Keyword(s):  
Hard Disk Drive ◽  
Failure Prediction ◽  
Hard Disk ◽  
Disk Drive
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