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Book Design Simulation and Optimization of Air Bearing Sliders Flying at Ultra low Spacing

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:

Book Journal of Tribology

Download or read book Journal of Tribology written by and published by . This book was released on 2007 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dynamics and Stability of Thermal Flying height Control Sliders in Hard Disk Drives

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.

Book Nonlinear Approaches in Engineering Applications

Download or read book Nonlinear Approaches in Engineering Applications written by Liming Dai and published by Springer. This book was released on 2018-01-29 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book analyzes the updated principles and applications of nonlinear approaches to solve engineering and physics problems. The knowledge on nonlinearity and the comprehension of nonlinear approaches are inevitable to future engineers and scientists, making this an ideal book for engineers, engineering students, and researchers in engineering, physics, and mathematics. Chapters are of specific interest to readers who seek expertise in optimization, nonlinear analysis, mathematical modeling of complex forms, and non-classical engineering problems. The book covers methodologies and applications from diverse areas such as vehicle dynamics, surgery simulation, path planning, mobile robots, contact and scratch analysis at the micro and nano scale, sub-structuring techniques, ballistic projectiles, and many more.

Book Numerical and Experimental Investigations of the Head disk Interface

Download or read book Numerical and Experimental Investigations of the Head disk Interface written by Maik Duwensee and published by . This book was released on 2007 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental techniques were developed for the investigation of slider dynamics for ultra-low spacing head/disk interfaces. Voltage pulsing and mapping techniques were established for the investigation of clearance and flying height modulation as functions of head/disk interface parameters. Numerical methods were developed to analyze forces acting on sliders of discrete track recording head/disk interfaces. A finite-element-based air bearing simulator was used to predict the steady state flying characteristics of arbitrarily shaped slider contours flying over discrete track recording disks. The direct simulation Monte Carlo method was used to simulate the rarefied gas flow in nano-channels.

Book Air Bearing Slider Dynamics and Stability in Hard Disk Drives

Download or read book Air Bearing Slider Dynamics and Stability in Hard Disk Drives written by Vineet Gupta and published by . This book was released on 2007 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Numerical Investigation of the Effects of Operational Shock and Disk Surface Pattern on the Dynamics of Head Disk Interface in Hard Disk Drives

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.

Book Experimental Study of Head disk Interface Dynamics Under the Condition of Near contact Recording for Magnetic Hard Disk Drives

Download or read book Experimental Study of Head disk Interface Dynamics Under the Condition of Near contact Recording for Magnetic Hard Disk Drives written by Mark Joseph Donovan and published by . This book was released on 1995 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Head disk suspension Dynamics

Download or read book Head disk suspension Dynamics written by Yong Hu and published by . This book was released on 1996 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book ASME Technical Papers

Download or read book ASME Technical Papers written by and published by . This book was released on 1999 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Paper

Download or read book Paper written by and published by . This book was released on 1999 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Numerical and Experimental Investigation of the Load unload Behavior of Subambient Pressure Hard Disk Drive Sliders

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: