scholarly journals A study on the running accuracy of an externally pressurized gas thrust bearing. 2nd report. Bearing stiffness and damping coefficient.

1989 ◽  
Vol 55 (510) ◽  
pp. 443-450
Author(s):  
Hiroshi YABE ◽  
Minoru YAMAMOTO
Keyword(s):  
Thrust Bearing ◽  
Damping Coefficient ◽  
Bearing Stiffness ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

A novel technique to compute static and dynamic performance characteristics of aerostatic thrust bearing

2018 ◽  
Vol 70 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Saurabh Kumar Yadav ◽  
Arvind Kumar Rajput ◽  
Nathi Ram ◽  
Satish Chandra Sharma
Keyword(s):  
Finite Element ◽  
Thrust Bearing ◽  
Dynamic Performance ◽  
Finite Element Formulation ◽  
Damping Coefficient ◽  
Element Formulation ◽  
Content Type ◽  
Novel Technique ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

Purpose This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e. circular, elliptical, rectangular and annular, have been considered in analysis. The work also analyzes the influence of tilt angle on the performance of thrust bearing. To compute the unknown pressure field, the Reynolds equation governing the flow of compressible lubricant (air) has been solved using finite element formulation. Further, separate finite element formulations have been carried out to compute fluid film stiffness and damping coefficients directly. This method provides quick computation of stiffness and damping coefficients of aerostatic thrust bearing than the usual approach. Design/methodology/approach As the Reynolds equation governing the flow of compressible lubricant is nonlinear partial differential equation, the computation of the stiffness and damping coefficient follows an iterative procedure. It requires a lot of computational energy. Therefore, in the present work, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing. Findings A novel technique based on finite element formulation is illustrated to simulate the performance of tilted pad aerostatic thrust bearing. On the basis of simulated results, following key conclusions may be drawn. The static and dynamic performance of a circular aerostatic tilted thrust pad bearing is significantly affected with a change in the value of tilt parameter and the shape of the recess. Research limitations/implications Implications are as follows: direct computation of air film damping coefficient is performed without perturbation method in finite element method (FEM); influence of tilt on aerostatic thrust bearing is studied; influence of recess shape on aerostatic thrust bearing is observed; and finite element formulation of aerostatic thrust bearing is performed. Originality/value The present work will be quite useful for bearing designer and academicians.

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.

Dynamic Analysis of High-Speed Hybrid Thrust Bearings

2013 ◽  
Vol 365-366 ◽  
pp. 304-308
Author(s):  
Lei Wang
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Dynamic Performance ◽  
Orifice Diameter ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Bearing Stiffness ◽  
Stiffness And Damping

An analysis is conducted and solutions are provided for the dynamic performance of high speed hybrid thrust bearing. By adopting bulk flow theory, the turbulent Reynolds equation is solved numerically with the different orifice diameter and supply pressure. The results show that increasing supply pressure can significantly improve the bearing stiffness and damping, while the orifice diameters make a different effect on the bearing stiffness and damping.

Rotor Vibration under the Coupled Effects of Mass Unbalance and Asymmetric Bearings

2016 ◽  
Vol 846 ◽  
pp. 199-204 ◽  
Author(s):  
Joseph Patrick Spagnol ◽  
Helen Wu
Keyword(s):  
Critical Speed ◽  
High Energy ◽  
Damping Matrix ◽  
Mass Unbalance ◽  
Rotor Bearing ◽  
Bearing Stiffness ◽  
Stiffness And Damping Coefficient ◽  
Early Fault Detection ◽  
Stiffness And Damping ◽  
Rotor Dynamic

Large unbalance in rotor-dynamic systems is typically responsible for high energy vibrations and the consequent decrease in machine life. This paper presents an analytical model developed using Lagrangian mechanics and partial differential equations (PDEs) for the purpose of early fault-detection in rotor-bearing systems. The model was validated through a Fortran based program, RDA99 developed by Adams (2010), by successfully quantifying the single-peak unbalance response of the simple 8 DOF and 12 DOF rotor-bearing mass stations over two cases. Case I uses bearings with symmetric stiffness and damping matrix. The critical speed for Case I occurred at 1690 rpm and orbital shapes of each mass station was found to be circular with forward-whirl orbits. In Case II asymmetrical bearing stiffness and damping coefficient matrices demonstrate an anisotropic system. Critical speed occurred at 1655 rpm and rotor, bearing and pedestal orbits were seen to be elliptical and changing with shaft speed. Both cases demonstrated a significant shaft bending contribution to the disk displacement.

scholarly journals Active Control Method Based on Equivalent Stiffness and Damping Coefficient for an Electromagnetic Isolation System

2020 ◽  
Vol 10 (22) ◽  
pp. 7953
Author(s):  
Lei Zhang ◽  
Xiangtao Zhuan
Keyword(s):  
Control Method ◽  
Dynamic Performance ◽  
Damping Coefficient ◽  
Stiffness Coefficient ◽  
Equivalent Stiffness ◽  
Isolation System ◽  
Performance Indexes ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Active Control Method

For improving the performance of an electromagnetic isolation system with reasonable parameters and avoid the parameter tuning problem of a PID controller, an active control method is put forward based on equivalent stiffness and damping coefficient. In this paper, the range of equivalent stiffness coefficient and damping coefficient of the electromagnetic force are calculated based on the required range of dynamic performance indexes. According to the nonlinear expression between electromagnetic force and coil current and gap, the relationships between the coil current and equivalent stiffness coefficient and damping coefficient are established. Then, the equivalent stiffness coefficient and damping coefficient can be satisfied by the controlled current in different gaps for meeting the required dynamic performance indexes. For reducing the maximum overshoot and the number of oscillations of the system, the active control method with the piecewise equivalent stiffness and damping coefficient is proposed based on the piecewise control strategy to realize the variable control parameters of the isolation system. Simulation and experimental results verify that the control method based on the equivalent stiffness and damping coefficient can obtain the desired dynamic performance indexes and the proposed control method with the piecewise strategy can not only reduce the setting time of the system, but also ensure the stability of the system.

Vibration of Elevator Cables With Small Bending Stiffness

2002 ◽  
Author(s):  
W. D. Zhu ◽  
G. Y. Xu
Keyword(s):  
Boundary Conditions ◽  
Bending Stiffness ◽  
Damping Coefficient ◽  
Lateral Vibration ◽  
Approximate Methods ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
Optimal Stiffness

The effects of bending stiffness and boundary conditions on the lateral vibration of the stationary and moving hoist cables are investigated. The role of the trial functions in the approximate methods is examined. The optimal stiffness and damping coefficient of the suspension of the car against its guide rails are identified for the moving cable.

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