scholarly journals Investigations of the static and dynamic characteristics of the precision hydrostatic spindle with mid-thrust bearing under different loads

2021 ◽  
pp. 135065012110236
Author(s):  
Chenggang Fang ◽  
Wucheng You ◽  
Dehong Huo
Keyword(s):  
Working Conditions ◽  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Thrust Bearing ◽  
Finite Difference Methods ◽  
Distribution Functions ◽  
Transient Pressure ◽  
Static And Dynamic Characteristics ◽  
Damping Characteristics ◽  
Stiffness And Damping

This paper investigates the static and dynamic characteristics of the precision hydrostatic spindle with a mid-thrust bearing under different working conditions. Firstly, the paper establishes the fluid governing equations of the coupled journal and thrust bearings based on orifice restrictors; and the dynamic and static Reynolds equations are solved using the perturbation and finite difference methods to obtain the steady and transient pressure distribution functions. Then the stiffness and damping characteristics of matrixes of the spindle are obtained by integrating the steady and transient pressure. Furthermore, by establishing the motion equation for the spindle rotor with five degrees of freedom, the quasi-static equilibrium position and stability criterion of the rotor under different working conditions are determined. Finally, the relationships between the dynamic and static characteristics of the spindle and cutting force, rotational speed, and cutting distance are simulated and analyzed. The simulation results show the patterns of variation in performance indices such as stiffness, damping, quasi-static position, and stability of the spindle under different working conditions, which provides important design information to be taken into consideration concerning the precision hydrostatic spindle.

Static and Dynamic Characteristics of Air Foil Thrust Bearing Considering Tilting Pad Condition

2007 ◽  
Author(s):  
Dong-Jin Park ◽  
Yong-Bok Lee ◽  
Chang-Ho Kim ◽  
Gun-Hee Jang
Keyword(s):  
Dynamic Characteristics ◽  
Carrying Capacity ◽  
Gas Turbines ◽  
Thrust Bearing ◽  
Load Carrying Capacity ◽  
Static And Dynamic Characteristics ◽  
Load Carrying ◽  
Foil Thrust Bearing ◽  
Thrust Pad ◽  
Stiffness And Damping

The thrust pad of the rotor is used to sustain the axial force generated due to the pressure difference between the compressor and turbine sides of turbomachinery such as the gas turbines and turbochargers. Furthermore, this thrust pad has a role to maintain and determines the attitude of the rotor. In a real system, it also helps reinforce the stiffness and damping of the journal bearing. This study was performed for the purpose of analyzing the characteristics of the air foil thrust bearing. The model for the air foil thrust bearing used in this study is composed of two parts: one is an inclined plane, which plays a role to increase the load carrying capacity using the physical wedge effect, and the other is a flat plane. This study mainly consists of three parts. First, the static characteristics were obtained over the region of the thin air film using the finite difference method (FDM) and the bump foil characteristics using the finite element method (FEM). Second, the analysis of the dynamic characteristics was conducted by perturbation method. For more exact calculation, the rarefaction gas coefficients perturbed about the pressure and film thickness were taken into consideration. At last, the static and dynamic characteristics of the tilting condition of the thrust pad were obtained. Furthermore, the load carrying capacity and torque were calculated for both tilting and not-tilting conditions. From this study, several results were presented: 1) the stiffness and damping of the bump foil under the condition of the various bump parameters, 2) the load carrying capacity and bearing torque at the tilting state, 3) the bearing performance under various bearing parameters, 4) the effects considering the rarefaction gas coefficients.

Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)

2000 ◽  
Vol 123 (3) ◽  
pp. 501-508 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kohno
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Bearing Surface ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Porous Bearing ◽  
Air Supply ◽  
Bearing Design

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.

An Efficient Technique for Design of Hydraulic Engine Mount via Design Variable-Embedded Damping Modeling

2005 ◽  
Vol 127 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Jun-Hwa Lee ◽  
Kwang-Joon Kim
Keyword(s):  
Dynamic Characteristics ◽  
Low Frequency ◽  
High Amplitude ◽  
Nonlinear Damping ◽  
Efficient Design ◽  
Equivalent Viscous Damping ◽  
Damping Characteristics ◽  
Design Variables ◽  
Engine Mount ◽  
Stiffness And Damping

For an efficient design of hydraulic mounts, it is most important to have a good mathematical model available, which must be simple yet capable of representing dynamic characteristics of the hydraulic mounts accurately. Under high amplitude excitations in the low-frequency range, the hydraulic mounts show strongly frequency-dependent stiffness and damping characteristics, which are related with so-called inertia track dynamics. Since nonlinear damping models based on fluid mechanics are typically used to predict the dynamic characteristics of the hydraulic mounts, relations between various design variables, such as geometry of the inertia track, and resultant stiffness and damping characteristics are understood only by tedious numerical computations. In this paper, the use of an equivalent viscous damping model—derived from a nonlinear model and represented in terms of design variables in an explicit manner—is proposed and, based on the equivalent linear model, are presented simple as well as very useful formulas for an efficient design of the hydraulic mounts.

Dynamic Characteristics of Spiral-Grooved Opposed-Hemisphere Gas Bearings

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Guangwei Yang ◽  
Jianjun Du ◽  
Weiping Ge ◽  
Tun Liu ◽  
Xiaowei Yang
Keyword(s):  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Translational Motion ◽  
Coupling Coefficients ◽  
Dynamic Coefficients ◽  
Large Eccentricity ◽  
The Stability ◽  
Stiffness And Damping ◽  
Gas Bearing

The traditional eight-coefficient bearing model only considers the translational motion of the bearings and neglects the tilting motion and coupling effects between them. In this paper, the dynamic characteristics of the spiral-grooved opposed-hemisphere gas bearing considering five degrees-of-freedom are studied, and 50 dynamic coefficients including the translational, tilting, and coupling components are completely calculated. The Reynolds equations and their perturbed equations are solved by the finite element method to obtain the dynamic stiffness and damping coefficients. The effects of the tilting motion on the dynamic coefficients and response are analyzed, respectively. The results show that the coupling coefficients between the translational and tilting motions, which have been neglected in most previous studies, are significant at large eccentricity ratio. But these coupling coefficients have little effect on the dynamic response. On the other hand, the influences of the tilting motion on the synchronous response and natural frequency are remarkable and will decrease the stability of the rotor bearing system.

Study on Static and Dynamic Characteristics of Load-Sensing and Pressure-Compensated Directional Control Valve

2013 ◽  
Vol 753-755 ◽  
pp. 2693-2699 ◽  
Author(s):  
Rui Lin Feng ◽  
Jian Hua Wei ◽  
Jin Hui Fang
Keyword(s):  
Transfer Function ◽  
Working Conditions ◽  
Dynamic Characteristics ◽  
Pressure Coefficient ◽  
Control Valve ◽  
Parameters Optimization ◽  
Static And Dynamic Characteristics ◽  
Load Sensing ◽  
Directional Control ◽  
Directional Control Valve

This study presents the static and dynamic characteristics of load-sensing and pressure-compensated directional control valve under the working conditions. A mathematical model is developed, two types of working conditions are presented through the static work point calculation. The static characteristic is analyzed by simulation, and the conclusion is validated by experiments. Solution procedure of the flow gain transfer function and flow-pressure coefficient transfer function is detailed introduced based on the above static computation, and their dynamic characteristic is analyzed by using Bode diagram. Finally, three types of compensatory modes are proposed, which provides very useful value and significance for the hydraulic component or system design and parameters optimization.

Stiffness and Damping Characteristics of a Wide Parabolic Film Slider Bearing Operating with Ferrofluids

2014 ◽  
Vol 1052 ◽  
pp. 132-136
Author(s):  
Jaw Ren Lin
Keyword(s):  
Magnetic Fields ◽  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Slider Bearing ◽  
Inclined Plane ◽  
Damping Characteristics ◽  
Plane Film ◽  
Stiffness And Damping

This paper investigates the dynamic characteristics of parabolic film slider bearing operating with ferrofluids. Comparing with the slider bearing of an inclined plane film, the parabolic film slider bearing operating with ferrofluids in the presence of external magnetic fields provide higher better dynamic stiffness and damping performances.

scholarly journals Effect of groove texture on the dynamic characteristics of water-lubricated thrust bearing

2018 ◽  
Vol 213 ◽  
pp. 01003
Author(s):  
Huihui Feng ◽  
Liping Peng
Keyword(s):  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Water Film ◽  
Geometrical Parameters ◽  
Damping Coefficients ◽  
Rotary Speed ◽  
Stiffness And Damping ◽  
Groove Texture ◽  
Film Lubrication

In this study, the effects of groove texture on the dynamic characteristics of water-lubricated thrust bearing are theoretically investigated. The turbulent Reynolds equation and its perturbation equations for water-film lubrication are derived and solved by using finite difference method. Dynamic characteristics including the stiffness and damping coefficients of the bearing are calculated. The effects of rotary speed, film clearance and geometrical parameters including groove texture depth and circumferential angle on the dynamic characteristics of the bearing have been investigated.

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