Polina V. Khan

Bifurcation Analysis of the Load/Unload Systems With Multiple Flying Height States

The load/unload behavior of the hard disk drive slider is studied in terms of the air bearing static characteristics. The application of numerical continuation methods to calculate spacing diagrams is proposed. The algorithm that detects multiple flying height states and fold points is developed. The relationship between suspension force x-offset and critical preload is found for femto size sliders. The second fold corresponding to the critical preload for unloading is found in the negative air bearing force area. The range of x-offsets and preloads where bi-stable phenomenon exists is depicted on the stability diagram. The perturbation method is used to check the dynamic system characteristic values near the fold points and to determine the stability of the solution branches. The present procedure can be employed to study the multiple flying height states in the terms of any other pair of parameters besides the preload and x-offset.

Application of Optimization Approach to Static FE Analysis of Hard Disk Drive Slider

The objective of the present work is to present the numerical analysis of the computer hard disk slider. The air film pressure is calculated using the finite element method. The conjugate-gradient method and the perturbation method are employed in the static analysis of the slider. The steady state attitude of the femto slider is studied for various radial positions and skew angles. It is found that the perturbation method is an efficient method for gradient evaluation. Also, it is shown that optimization of the Hessian matrix form accelerates the search process.

Non-Iterative Finite Element Scheme for Combined Annular-Thrust Porous Aerostatic Bearings Analysis

The key points of method derivation and a numerical example for bearing with three dimensional air flow are presented.Copyright

The effect of the arc on annular-thrust aerostatic porous bearings

Purpose Aerostatic porous bearings are important for guide rails and spindles. It is well-known that flow restrictors made of porous materials offer major advantages over conventional restrictors in such bearings, including design and manufacturing, load-carrying capacity, stiffness, damping and dynamic stability. Thus, this work numerically investigates the effect of the arc on a new combined annular-thrust aerostatic porous bearing. Design/methodology/approach The static characteristics of an annular-thrust aerostatic porous bearing were studied using a fast finite element scheme. The pressure distribution, radial load and thrust load were analyzed as functions of the arc, permeability and eccentricity. Findings The results reveal that the radial load achieves maximal values at an optimal arc value between 200 and 300, and the thrust load increases monotonically with increasing arc. Originality/value This work developed a new combined annular-thrust aerostatic porous bearing to investigate the effect of arc on the annular-thrust aerostatic porous bearings to increase the load-carrying capacity.

A STUDY OF HEAD–DISK INTERACTION DETECTION IN THE HARD-DISK DRIVES

The reliability and performance of precision mechanical components that experience sliding under contact depend heavily on the friction and wear characteristics at the sliding interface. In order to improve the reliability of the sliding interface, there is a need to predict, measure and monitor any physical interactions at the head–disk interface (HDI). In the present work, the basic tribological characteristics of HDI were analyzed. The HDI during start–stop and constant speed operation using acoustic emission (AE) were studied. The Fast Fourier Transform (FFT) analysis of the AE signal was used to understand the interaction between the AE signal and the state of contact. In addition, we developed laser textured (LT) disk and the contact start–stop (CSS) tests were performed to investigate the effect of dimples on the stiction performance of the HDI. Furthermore, numerical analysis between the slider and disk surface pressure were performed using the boundary coordinate system and divergence formulation for the nonlinear Reynolds equation solution.