Stiffness and Damping of Compressible Lubricating Films Between Computer Flying Heads and Textured Media: Perturbation Analysis Using the Finite Element Method

1991 ◽  
Vol 113 (4) ◽  
pp. 819-827 ◽  
Author(s):  
Y. Mitsuya ◽  
H. Ota
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Film Thickness ◽  
Damping Coefficient ◽  
The Finite Element Method ◽  
Damping Force ◽  
Spacing Variation ◽  
Transverse Roughness ◽  
Stiffness And Damping ◽  
Element Method

Averaged static and dynamic lubrication equations are derived in the general form containing anisotropic film thicknesses dependent on roughness orientation. Solving these equations lead to a presentation of the dynamic characteristics of lubricating films existing between computer flying heads and textured media. Squeeze effects owing to moving roughness accompanying high-frequency spacing variation are found to be given as a function of arithmetically averaged film thickness minus harmonically averaged film thickness. The calculation procedure using the finite element method is then presented for the averaged static and dynamic lubrication equations. Stiffness and damping coefficient are demonstrated indicating the effects of roughness orientation and roughness movement. Under the fixed static film conditions, the roughness decreases the stiffness. In contrast to this, the roughness only slightly affects the damping coefficient. Under fixed load and loading point conditions, these relationships are inversed. It is interesting to note that damping coefficients are decreased by longitudinal roughness and are increased by moving transverse roughness. The reason for this tendency is considered to be that the moving transverse roughness serves to generate the squeeze damping force.

Study on Dynamics Characteristics of SINS Damping System in Shock Environment

2013 ◽  
Vol 397-400 ◽  
pp. 355-358
Author(s):  
Xia Qing Tang ◽  
Jun Qiang Gao ◽  
Li Bin Guo ◽  
Huan Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Optimal Design ◽  
Vibration Isolation ◽  
Damping Coefficient ◽  
Shock Environment ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Element Method

Dynamics characteristics of SINS damping system in shock environment were analyzed by finite element method, as the deformation of dampers may leads to the accuracy loss of SINS. In addition, the influence of absorber stiffness and damping coefficient on dynamics characteristics were studied. The results indicate that the decoupling of vibrations is significant for the accuracy of SINS. However, considering the almost impossible of completely decoupled vibrations, its necessary to carry out an optimal design of the absorber stiffness and damping coefficient to maintain the accuracy of SINS while meeting the requirement of vibration isolation.

Modelling of the Behaviour of Dynamical Gas Seals: Calculation with a Finite Element Method Implicitly Assuring the Continuity of Flow

1995 ◽  
Vol 209 (3) ◽  
pp. 195-201 ◽  
Author(s):  
P Hernandez ◽  
R Boudet
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Results ◽  
The Body ◽  
Dynamical Model ◽  
The Finite Element Method ◽  
Flow Through ◽  
Gas Seals ◽  
Stiffness And Damping ◽  
Element Method

The objective of this paper is to present a model of the behaviour of dynamical seals and the corresponding numerical results. These seals are used in the mechanism to realize partial sealing when the relative rotating speeds are too high for usual solutions. The studied seals mainly include two discs: one is attached to the shaft and the other to the body, the last one being pushed and the first being attached by springs. During operation, a gaseous film is created between the discs, preventing any contact. The control of the film thickness allows the leakage flow to be controlled. For the behaviour of such mechanisms, an analytical formulation of the problem is firstly presented. Then a geometrical and kinematical model having one degree of freedom is proposed to model the mechanism having two discs in relative rotation, one of which is spirally grooved. A dynamical model associated with the motion of the disc attached to the body has been developed and the mechanics of thin viscous films is used to study the behaviour of the gaseous film at the interface. Utilization of the finite element method in the mechanics of thin viscous films is introduced and a description of the elements used is presented. The influence of the groove's angle and the groove's depth is shown through numerical results concerning leakage mass flow through the mechanism and the loading capacity of the fluid film, as well as the coefficients of stiffness and damping associated with the dynamical model.

Numerical investigation on the static performance of aerostatic journal bearings with different pocket shapes by the finite-element method

2020 ◽  
pp. 135065012097911
Author(s):  
Xinglong Chen ◽  
James K Mills ◽  
Kai Shi ◽  
Gang Bao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Film Thickness ◽  
Journal Bearings ◽  
Orifice Diameter ◽  
Eccentricity Ratio ◽  
The Finite Element Method ◽  
Area Formula ◽  
Static Performance ◽  
Element Method

In this work, to improve the static behavior of aerostatic journal bearings, we examine the effect of pockets with different shapes, including the square, rectangular 1, rectangular 2, and circular, manufactured on the surface of the aerostatic journal bearing. The effects of the pocket shapes, pocket area [Formula: see text], eccentricity ratio ɛ, orifice diameter df, average gas film thickness h0, and misalignment angles [Formula: see text] and [Formula: see text] on the static performance are investigated using simulations. The Reynolds equation is solved by the finite-element method in this work. Simulations reveal that the pocket area [Formula: see text], eccentricity ratio ɛ, gas film thickness h0, orifice diameter df, and misalignment angles [Formula: see text] and [Formula: see text] have a significant influence on the load force F and the stiffness K. In general, rectangular 2 pocket bearings are found to perform somewhat better than bearings with other pocket shapes, with the pocket depth set to one-half of h0, when the pocket area [Formula: see text] varies from one-twelfth to one. The pocket area [Formula: see text] should be set according to the average gas film thickness h0 and the orifice diameter df to achieve a better static performance for the bearings. For bearings operated with misalignment angles [Formula: see text] and [Formula: see text], different pocket areas [Formula: see text] should be set according to the pocket shapes for the optimal design.

scholarly journals NUMERICAL CALCULATION OF THE STIFFNESS OF THE ELASTIC BLOCK OF THE HYDRAULIC SUPPORT SHELL BY THE FINITE ELEMENT METHOD

2021 ◽  
pp. 22-35
Author(s):  
B.A. Gordeev ◽  
S.N. Ohulkov ◽  
A.N. Osmekhin ◽  
A.S. Plekhov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Shell ◽  
Safety Margin ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Hydraulic Support ◽  
Subsequent Determination ◽  
Stiffness And Damping ◽  
Element Method

The article presents the calculation of the stiffness of the elastic shell of hydraulic supports by the finite element method. This calculation is necessary to know the safety margin of the rubber shell, since with an increase in the resulting vibration, the service life of the MR-hydraulic support decreases, leading to its destruction [1, 2]. The purpose of this study is to calculate and evaluate the maximum shear deformations of the rubber shell of the hydraulic support necessary for the subsequent determination of the stiffness and damping of the hydraulic support at resonant frequencies. The finite element method is used to estimate the maximum shear deformations of the rubber shell of the hydraulic support caused by variable loads.

On the Choice of Element for Solving Lubrication Problems

1998 ◽  
Vol 120 (3) ◽  
pp. 636-639
Author(s):  
Ram Turaga ◽  
A. S. Sekhar ◽  
B. C. Majumdar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
High Eccentricity ◽  
Damping Coefficients ◽  
Significant Difference ◽  
The Stability ◽  
Stiffness And Damping ◽  
Element Method

This study deals with the stability characteristics of journal bearings using the finite element method. Two different elements, a 3-node linear triangle and a 6-node quadratic triangle, have been used. The results show a significant difference in (1) stiffness and damping coefficients and (2) stability characteristics at high eccentricity ratios due to the use of the two different elements.

Simulation of tuning graphene plasmonic behaviors by ferroelectric domains for self-driven infrared photodetector applications

Nanoscale ◽  
2019 ◽  
Vol 11 (43) ◽  
pp. 20868-20875 ◽  
Author(s):  
Junxiong Guo ◽  
Yu Liu ◽  
Yuan Lin ◽  
Yu Tian ◽  
Jinxing Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Interfacial Effect ◽  
Infrared Photodetector ◽  
The Finite Element Method ◽  
Ferroelectric Domains ◽  
Element Method

We propose a graphene plasmonic infrared photodetector tuned by ferroelectric domains and investigate the interfacial effect using the finite element method.

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