The molecular dynamics simulation of ultra-thin films under confined shear was performed to investigate the relation between dynamic properties of ultra-thin films and their microstructure. The solid walls were modell...The molecular dynamics simulation of ultra-thin films under confined shear was performed to investigate the relation between dynamic properties of ultra-thin films and their microstructure. The solid walls were modelled using an Au crystal and the fluid molecules were modeled using decane. The simulation results indicate that the microstructure of ultra-thin films is a kind of solid-like layering structure. The density and velocity profiles of the fluid molecules are symmetric. The slip and shear thinning behavior was founded and interpreted.A mathematic model was set up according to the results of the simulation and experiments.展开更多
The modified Reynolds equation for ultra-thin gas films between magnetic head and disk assembly is difficult to solve with conventional numerical methods, since the bearing number is very large and there exist boundar...The modified Reynolds equation for ultra-thin gas films between magnetic head and disk assembly is difficult to solve with conventional numerical methods, since the bearing number is very large and there exist boundary layers where pressure changes rapidly. An iterative finite difference algorithm is introduced to solve the nonlinear modified Reynolds equation, with special treatment for the abrupt change in the thickness of the gas film. The numerical results for two types of magnetic heads demonstrate that the scheme is effective.展开更多
This paper presents a pressure perturbation equation for the ultra-thin gas film lubrication of magnetic head-disk based on a generalized gas lubrication equation applicable to arbitrary Knudsen number. The gas film p...This paper presents a pressure perturbation equation for the ultra-thin gas film lubrication of magnetic head-disk based on a generalized gas lubrication equation applicable to arbitrary Knudsen number. The gas film pressure of Air Bearing Slider (ABS) was obtained by using the operator-splitting and finite element method. The pressure perturbation equation was solved by the finite element method with unstructured triangle grids to calculate the stiffness and damping coefficients of the gas film. Modal analysis of coupled system of magnetic head and gas film was carried out to obtain natural frequencies, damping rates and mode shapes of the magnetic head vibrations. Vibration stability of Ω-type magnetic head was predicted in this work. Numerical results indicate that the natural frequencies of the coupled system increases as the gas film thickness decreases, and the natural frequencies and damping rate of the coupled vibration modes of heave and pitch motions are much lower than those of uncoupled modes. And it is concluded that the stability of magnetic head is slightly worsened when the disk rotation speed increases.展开更多
文摘The molecular dynamics simulation of ultra-thin films under confined shear was performed to investigate the relation between dynamic properties of ultra-thin films and their microstructure. The solid walls were modelled using an Au crystal and the fluid molecules were modeled using decane. The simulation results indicate that the microstructure of ultra-thin films is a kind of solid-like layering structure. The density and velocity profiles of the fluid molecules are symmetric. The slip and shear thinning behavior was founded and interpreted.A mathematic model was set up according to the results of the simulation and experiments.
基金Supported by the Project of the State Key Basic Research and Development of China (Grant No. 2003CB716205)
文摘The modified Reynolds equation for ultra-thin gas films between magnetic head and disk assembly is difficult to solve with conventional numerical methods, since the bearing number is very large and there exist boundary layers where pressure changes rapidly. An iterative finite difference algorithm is introduced to solve the nonlinear modified Reynolds equation, with special treatment for the abrupt change in the thickness of the gas film. The numerical results for two types of magnetic heads demonstrate that the scheme is effective.
基金the National Natural Science Foundation of China (Grant No: 10072022)
文摘This paper presents a pressure perturbation equation for the ultra-thin gas film lubrication of magnetic head-disk based on a generalized gas lubrication equation applicable to arbitrary Knudsen number. The gas film pressure of Air Bearing Slider (ABS) was obtained by using the operator-splitting and finite element method. The pressure perturbation equation was solved by the finite element method with unstructured triangle grids to calculate the stiffness and damping coefficients of the gas film. Modal analysis of coupled system of magnetic head and gas film was carried out to obtain natural frequencies, damping rates and mode shapes of the magnetic head vibrations. Vibration stability of Ω-type magnetic head was predicted in this work. Numerical results indicate that the natural frequencies of the coupled system increases as the gas film thickness decreases, and the natural frequencies and damping rate of the coupled vibration modes of heave and pitch motions are much lower than those of uncoupled modes. And it is concluded that the stability of magnetic head is slightly worsened when the disk rotation speed increases.
