Download or read book Physical Modeling and Numerical Simulations of the Slider Air Bearing Problem of Hard Disk Drives written by Lin Wu and published by . This book was released on 2001 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Rarefied and Contact Air Bearing Modeling for Hard Disk Drives Using the Direct Simulation Monte Carlo Method written by Weidong Huang and published by . This book was released on 1998 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Principles of Tribology written by Shizhu Wen and published by John Wiley & Sons. This book was released on 2012-02-21 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Professors Wen and Huang present current developments in tribology research along with tribology fundamentals and applications, including lubrication theory, lubrication design, friction mechanism, wear mechanism, friction control, and their applications. In addition to classical tribology, Wen and Huang cover the research areas of the modern tribology, as well as the regularities and characteristics of tribological phenomena in practice. Furthermore, the authors present the basic theory, numerical analysis methods, and experimental measuring techniques of tribology as well as their applications in engineering. Provides a systematic presentation of tribology fundamentals and their applications Discusses the current states and development trends in tribology research Applies the applications to modern day engineering Computer programs available for download from the book’s companion site Principles of Tribology is aimed at postgraduates and senior-level undergraduates studying tribology, and can be used for courses covering theory and applications. Tribology professionals and students specializing in allied areas of mechanical engineering and materials science will also find the book to be a helpful reference or introduction to the topic. Companion website for the book: www.wiley.com/go/wen/tribology
Download or read book Numerical Simulation of Slider Air Bearings in Head disk Interface System Based on a Mesh free Method written by Xu Hong Li and published by . This book was released on 2006 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulations of the Head disk Interface in Hard Disk Drives written by Puneet Bhargava and published by . This book was released on 2008 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical and Experimental Investigation of the Load unload Behavior of Subambient Pressure Hard Disk Drive Sliders written by Stefan Weissner and published by . This book was released on 2001 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Slider and Airbearing in Hard Disk Drives written by Gobinath Arvind Athappan and published by . This book was released on 1995 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Tribology written by and published by . This book was released on 2006 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Investigation of Operational Shocks and Vibrations in Mobile Hard Disk Drives written by Rahul Rai and published by . This book was released on 2011 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, there has been a continuous increase in the demand of hard disk drives (HDDs) for the mobile applications. In such devices, HDDs are often subjected to mechanical shocks and vibrations. Such external disturbances can degrade the read/write (R/W) performance of mobile drives and in extreme cases it can even cause the loss of stored magnetic information. Hence the ability of the head-disk interface (HDI) to withstand such excitation becomes critical in determining the reliability of a mobile disk drive. This dissertation presents a simulation method to accurately model the response of a mobile HDD to external disturbances which can aid the design process. A numerical investigation was conducted on a 2.5 inch form factor laptop drive to understand the dynamics of the HDI during dynamic events such as operational shocks. A detailed model for the mobile disk drive was developed which includes a spinning disk, a fluid dynamic bearing (FDB) based spindle motor, a base plate and an actuator. The behavior of the HDI subjected to various disturbances was determined by solving a fluid-structure interaction problem in which a spinning disk and a head (slider) were coupled through an air bearing. Case studies were conducted to determine the effect of parameters like shock pulse width, HDD orientation, parking ramp contact and FDB dynamic coefficients on the performance of a HDD during the excitation. It was observed that the proximity of the pulse to the HDD component's natural frequencies has an adverse effect on the shock resistance of the HDI. Furthermore, the orientation of the HDD during the shock can also affect the stability of the HDI. In the case of planar excitations, the FDB dynamics becomes critical in determining the slider's vibration amplitude. This knowledge about the HDI failure mechanism and its vibration characteristics can be helpful in designing a mobile HDD with a better shock performance.
Download or read book Proceedings of the ASME STLE International Joint Tribology Conference written by and published by . This book was released on 2004 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Simulation and Optimization of Air Bearing Sliders Flying at Ultra low Spacing written by Jiadong Zhang and published by . This book was released on 2005 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics and Stability of Thermal Flying height Control Sliders in Hard Disk Drives written by Jinglin Zheng and published by . This book was released on 2012 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a recent development to further reduce the flying height of a magnetic head in hard disk drives (HDDs) to nanometers, thermal flying-height (TFC) control technology is now widely applied in the HDD industry because it enables consistent read/write spacing, increased storage density and improved HDD reliability. The fast development of TFC technology presents new challenges to head designers because of the complicated structure of a TFC head, the thermo-mechanical-coupling effects and tribology issues arising at nanometer read/write spacing. A steady-state TFC solver dedicated to obtaining the steady-state flying attitude of a TFC slider is developed in this thesis. This solver uses a finite volume based solver (CML static solver) to solve the generalized Reynolds equation and obtain the pressure and spacing fields in the air bearing and a commercial coupled-field solver (ANSYS) to obtain the stress and strain fields due to internal heating. An iterative procedure is adopted to consider the cooling effect of the air bearing on the heater-induced protrusion. Accuracy of the solver is verified by drive-level magnetic tests on several combinations of air bearing and heater designs. TFC sliders' performances under different ambient conditions are investigated based on the TFC solver. It is found that the thermal actuation efficiency of a TFC slider increases with altitude because of the weakened cooling and reduced air bearing stiffness at the transducer area at a higher altitude. In addition, a TFC slider maintains a more consistent read/write spacing at different humidity levels, compared with a non-TFC slider, because the thermal actuation is able to compensate part of the pressure loss caused by water condensation. A TFC slider's flying height in air-helium mixtures is shown to be a highly nonlinear function of the fraction of helium in the gas mixture due to the combined effects of the gas mean free path, viscosity and heat conductivity. These results provide general guidelines for heater and ABS designers to reduce a TFC slider's sensitivity to ambient conditions and improve HDD reliability. A touchdown numerical model for predicting TFC sliders' dynamics at touchdown and over-pushed conditions is developed and implemented based on the CML dynamic simulator. It extends the solution of the time-varying generalized Reynolds equation to near-contact and contact conditions using a statistical multi-asperity approach. Various interfacial forces are considered by use and further development of a sub-boundary lubrication model to capture important tribological effects occurring at touchdown. This model is able to predict a TFC slider's unstable dynamics at the beginning of touchdown, which has been discovered in many related experimental studies. The effects of different head-disk interface factors are investigated using this numerical model. It is found that the suspension is actively involved in the TFC slider's bouncing vibrations and has a significant influence on the excited second air bearing pitch mode. It is also shown that adhesion force serves as an essential factor in exciting the second air bearing mode whereas other interfacial forces only affect details of the slider's bouncing behaviors. By changing the interfacial properties, namely, the interface roughness and lubricant thickness, the variation of interfacial forces with spacing reduction differs, which leads to very different touchdown patterns. With a rougher interface profile the slider smoothly transfers from a flying stage to a sliding stage. With a smoother interface profile the slider experiences a flying-bouncing-sliding transition. With the smoothest interface the slider goes through a flying-bouncing-surfing-sliding transition. The touchdown behaviors predicted by the numerical simulator are correlated with experiments conducted on industry-provided head parts with the same ABS and suspension design. Similar touchdown stages and excited modes are also discovered in the experiments. Though experiments showed a slider spectrum with richer frequency components, the modes missed from the numerical simulations are recovered by conducting a harmonic analysis on a full HGA model with air bearing included. The different touchdown dynamic patterns predicted here result in significant differences in the successful touchdown detection, which is very important for realizing reliable read/write operations, and therefore this work provides guidelines for head disk interface (HDI) optimization. The general approach proposed here is also applicable to studies on the effects of other important HDI factors, such as air bearing geometric features, heater-induced protrusion profiles, and suspension design parameters, and on the slider's touchdown dynamics behaviors, which will assist in obtaining solutions to performance and reliability issues in current hard disk drives.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2001 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the World Tribology Congress III 2005 written by and published by . This book was released on 2005 with total page 1114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Investigation of the Effects of Operational Shock and Disk Surface Pattern on the Dynamics of Head Disk Interface in Hard Disk Drives written by Liping Li and published by . This book was released on 2013 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the effects of shock and the disk surface pattern on the head disk interface (HDI) response in hard disk drives (HDDs). A new local adaptive mesh method is proposed at the end to improve the accuracy and efficiency of the algorithm to simulate the sliders' steady flying attitudes. Over the past decades, there has been an increase in the demand of HDDs used in portable devices. In such applications, the work performance of a HDD mainly depends on its ability to withstand external disturbances. Studies of the HDD's responses and failures during external shocks can be very beneficial for improving the HDD's design. A multi-body operational shock (op-shock) model is developed for this purpose in this thesis. The Guyan reduction method is used to model all the components considered in the op-shock model (a disk, a spindle motor, a base plate, a pivot and a head actuator assembly (HAA)). A fluid dynamic bearing (FDB), between the rotating and stationary units in the spindle motor, is simplified as a spring-dashpot system to save computation efforts. The same simplification is applied to a ball bearing (BB) system between the rotating and stationary units in the actuator pivot. Then the reduced models for all the components are assembled to obtain a complete multi-body op-shock model. Four models which include different components are introduced in this thesis to investigate various components' effects on the HDD's operating performance. The HDDs' failure mechanisms are also studied. It is found that different components influence the HDI responses in different ways. The ramp load/unload (LUL) technology has been proved to be a better alternative to the contact start-stop (CSS) approach due to the advantages of increasing areal density and greater durability. However, the application of the LUL ramps in the HDDs increases the possibility of collisions between the disk and the ramps since the ramps sit closely to the disk's outer radius. Therefore, it is important to study the ramp effects on the HDD's response during a shock. A reduced model of a deformable ramp is developed and implemented to the multi-body op-shock model. Numerical analyses using three ramp models (no-ramp model, rigid ramp model and deformable ramp model) are carried out to study the HDD's failure dependence on different ramp models. Bit patterned media (BPM) recording is one of the promising techniques for future disk drives in order to increase the areal density above 4 Tbit/in2. In patterned media, an individual recorded bit is stored in a distinct magnetic island. Thus, the BPM can change the topography of the disk surface and has an effect on the flying characteristics of the air bearing sliders. Proper designs of sliders and disks in the HDDs are required in order to achieve a stable work performance. So a simulator to model a slider's flying condition over a BPM disk is particularly important. Three methods (the averaging method, the Homogenization method and the Taylor expansion Homogenization methods) are implemented to simulate a slider's flying attitude, and finally an economical accurate method is chosen (the Taylor expansion Homogenization method) to investigate the slider's dynamics on partially planarized patterned media. In modern HDDs, the requirement of small and steady head disk spacing leads to more complicated air bearing surface designs. Thus it is challenging for an air bearing simulator to accurately capture the pressure under a slider's surface. A new local adaptive grid-generating algorithm is developed and is used to simulate the sliders' steady flying attitude. Local finer meshes (mesh's dimension decreases to half) are created on the nodes of the current grids, which have pressure gradients or geometry gradients larger than a pre-defined tolerance. Two sliders are used to demonstrate the applicability of this method. It is found that this new local adaptive grid-generating method improves the stability and efficiency of the simulation scheme.
Download or read book Tribological Study of Contact Interfaces in Hard Disk Drives written by Youyi Fu and published by . This book was released on 2016 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: To achieve an areal density of 1 terabits per square inch (1.55 gigabits/mm2) in hard disk drives, the size of magnetic grains in hard disks has been reduced to approximately 7 nm and the spacing between the magnetic head and the disk has been minimized to 1 to 2 nm. At a spacing on the order of 1 to 2 nm between the head and the disk, it is likely that contacts between the magnetic head and the disk occur during reading and writing, causing erasure of data or even failure of the head/disk interface. Wear particles can be generated as a consequence of contacts between slider and disk, and if particles enter the head/disk interface, catastrophic failure of the head/disk interface can occur. To reduce the generation of wear particles and avoid failure of the head/disk interface, it is important to investigate how the tribological performance of all contact interfaces in hard disk drives can be improved. In this dissertation, the tribological performance of the most important contact interfaces in a hard disk drive are investigated with a focus on the generation of wear particles and lubricant migration. First, fretting wear is investigated to study the effect of a diamond-like carbon (DLC) overcoat on wear of the dimple/gimbal interface. A numerical simulation model based on finite element analysis was developed to explain the experimental results. Then, lubricant migration on the air bearing surface and its effect on the head medium spacing (HMS) was investigated as a function of temperature, slider position, and "parking time" of the slider on the ramp. Thereafter, the thermal response of a thermal sensor during contact with asperities on the disk surface was analyzed. The effects of experimental and environmental conditions on the resistance change of the sensor were studied. Finally, experimental and numerical investigations were performed to analyze contact between the suspension lift tab and the ramp in hard disk drives. The voice coil motor current was used to characterize the change of the friction force and the generation of wear debris at the lift tab/ramp interface during load/unload testing. Numerical simulations were performed to analyze how to reduce contact stress between the lift-tab and the ramp. The results of this dissertation will be helpful in improving the tribological performance of hard disk drives.
