scholarly journals Influence of Temperature Effect on the Static and Dynamic Performance of Gas-Lubricated Microbearings

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 716
Author(s):  
Liangliang Li ◽  
Zhufeng Liu ◽  
Chongyu Wang ◽  
Yonghui Xie
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Operating Environment ◽  
Low Friction ◽  
Operating Stability ◽  
Comprehensive Performance ◽  
Different Temperatures ◽  
Dynamic Performances ◽  
The Difference

Gas-lubricated microbearings are widely applied in multiple fields due to their advantages of high-speed, low friction level and other features. The operating environment of microbearings is complex, and the difference of temperature has an important influence on their comprehensive performance. In this investigation, FEM (finite element method) is employed to investigate the static, dynamic and limit characteristics of microbearings lubricated by different kinds of gas at different temperatures. The results show that the rise of temperature leads to the decline of equivalent viscosity of gas, which weakens the load capacity of microbearings, and furthermore, affects the operating stability of microbearings. The dynamic performances of microbearings at different temperatures are very different, and the two dynamic limit characteristics are more sensitive to temperature when it changes.

Study on Dynamic Performance of the Non-Circular Bearings Using Fourier Analysis

2018 ◽  
Author(s):  
Jiale Tian ◽  
Baisong Yang ◽  
Lie Yu ◽  
Jian Zhou
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Fourier Method ◽  
Oil Film ◽  
Dynamic Performances ◽  
Recent Trends ◽  
Harmonic Components ◽  
Stiffness And Damping

Journal bearing is one of the most important components for supporting high speed rotating machinery such as compressors and turbo machines. In recent trends, non-circular journal bearings (lemon bearing, three-lobe bearing, four-lobe bearing, etc.), for their greater load capacity and better stability, have become a superior choice and found wide spread application. In this paper, the nonlinear oil film force is expressed using the dynamic stiffness and damping of 1st-3rd order. And the film thickness and pressure are analyzed using Fourier method, so that the corresponding harmonic components and their deeper connection can be further explored. The paper shows that the nonlinear dynamic performances are connected closely with the bearings’ profile, and lays the foundation for expressing the precise nonlinear oil film force.

scholarly journals A Novel Stick-Slip Nanopositioning Stage Integrated with a Flexure Hinge-Based Friction Force Adjusting Structure

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 765
Author(s):  
Junhui Zhu ◽  
Peng Pan ◽  
Yong Wang ◽  
Sen Gu ◽  
Rongan Zhai ◽  
...  
Keyword(s):  
Friction Force ◽  
High Speed ◽  
Simulation Analysis ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Vertical Direction ◽  
Flexure Hinge ◽  
Stick Slip ◽  
Static Performance

The piezoelectrically-actuated stick-slip nanopositioning stage (PASSNS) has been applied extensively, and many designs of PASSNSs have been developed. The friction force between the stick-slip surfaces plays a critical role in successful movement of the stage, which influences the load capacity, dynamic performance, and positioning accuracy of the PASSNS. Toward solving the influence problems of friction force, this paper presents a novel stick-slip nanopositioning stage where the flexure hinge-based friction force adjusting unit was employed. Numerical analysis was conducted to estimate the static performance of the stage, a dynamic model was established, and simulation analysis was performed to study the dynamic performance of the stage. Further, a prototype was manufactured and a series of experiments were carried out to test the performance of the stage. The results show that the maximum forward and backward movement speeds of the stage are 1 and 0.7 mm/s, respectively, and the minimum forward and backward step displacements are approximately 11 and 12 nm, respectively. Compared to the step displacement under no working load, the forward and backward step displacements only increase by 6% and 8% with a working load of 20 g, respectively. And the load capacity of the PASSNS in the vertical direction is about 72 g. The experimental results confirm the feasibility of the proposed stage, and high accuracy, high speed, and good robustness to varying loads were achieved. These results demonstrate the great potential of the developed stage in many nanopositioning applications.

scholarly journals Dynamic Modelling and Analysis of the Microsegment Gear

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Yangshou Xiong ◽  
Kang Huang ◽  
Tao Wang ◽  
Qi Chen ◽  
Rui Xu
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Dynamic Modelling ◽  
Weight Ratio ◽  
Load Condition ◽  
Main Idea ◽  
Heavy Load ◽  
Rotating Speed ◽  
Involute Gear

The development of technology requires higher load capacity, rotating speed, power-weight ratio, lower vibration, and noise with respect to the gear transmission. The new type microsegment gear’s tooth profile curve is composed of many microsegments. Previous researches indicate that the microsegment gear has a good static performance, while the dynamic behavior of the microsegment gear has never been investigated. This paper will focus on the dynamic performance of the gear. The profile deviation between microsegment gear and involute gear is regarded as a displacement excitation in the proposed dynamic model. The numerical analysis for three cases is conducted and the results shows that, in low-speed and heavy-load, medium-speed and medium-load conditions, microsegment gear and involute gear both exhibit a good performance, while, in high-speed and heavy-load condition, microsegment gear has a better performance than that of involute gear. The influence of backlash on the dynamic performance is also studied. It is found that the variation of backlash does not change the type of motion, but the vibration amplitude and the stability of the motion are much affected. The main idea in this paper is supposed to provide a novel method for the precision grinding of the microsegment gear.

Dynamics modeling and analysis of a four-wheel independent motor-drive virtual-track train

2020 ◽  
pp. 146441932096401
Author(s):  
Zhonghui Yin ◽  
Jiye Zhang ◽  
Haiying Lu ◽  
Weihua Zhang
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Spatial Dynamics ◽  
Dynamic Responses ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Coupling Effects ◽  
Dynamic Interactions ◽  
Modeling And Analysis

Due to urbanisation and the economic challenges of traffic, it is urgently necessary to develop an environmentally friendly virtual-track train with suitable speed, high load capacity and low construction cost in China. To guide the design and evaluate this train’s dynamic behaviour, a spatial-dynamics model has been developed based on the dynamics theory and tyre-road interaction. The proposed dynamics model comprises mechanical vehicle systems, traction and braking characteristics and tyre-road dynamic interactions. The coupling effects amongst those systems of virtual track train are derived theoretically for the first time. The nonlinear characteristics of the tyre are modelled by the transit tyre-magic formula with consideration of road irregularities. Based on a designed PID controller and the comprehensive dynamics model, the dynamic performance of the system can be revealed considering motion coupling effects and complicated excitations, especially under traction and braking conditions. The dynamic responses of whole virtual track train can be obtained by numerical integration under different conditions. The vibration characteristics of such train are assessed under running at a constant speed and during the traction/braking process. The results show that the vibrations of the vehicle system are significantly influenced by road irregularities, especially at high speed ranges. The motions and vibrations of different components are intensive coupled, which should not to be neglected in the dynamics assessment of the virtual track train. Besides, the dynamics model can also be applied to dynamics-related assessment (fatigue, strength and some damage conditions, et al.) and parameter optimisation of the virtual-track train.

Effect of misalignment and rarefaction effect on the comprehensive characteristic of MEMS gas bearing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liangliang Li ◽  
Yonghui Xie
Keyword(s):  
Peer Review ◽  
High Speed ◽  
Rarefied Gas ◽  
Load Capacity ◽  
Content Type ◽  
Rarefaction Effect ◽  
Comprehensive Performance ◽  
Static Performance ◽  
The Stability ◽  
Gas Bearing

Purpose Owing to the development of the smaller-sized rotational machinery, the demand for the high-speed and low-resistance gas bearing increases rapidly. The research of micro gas bearing in the condition of rarefied gas state is still not satisfied. Therefore, the purpose of this paper is to present a numerical investigation of the effect of misalignment and rarefaction effect on the comprehensive performance of micro-electrical-mechanical system (MEMS) gas bearing. Design/methodology/approach The Fukui and Kaneko model is expanded to 2D solution domain to describe the flow field parameters. The finite element method is used to discretize the equation. Newton–Raphson method is used to solve the nonlinear equations for the static performance of gas bearing, and partial deviation method is adopted for the solution of dynamic equations. Findings The static and dynamic characteristics of MEMS gas bearing are calculated, and the comparison is made to study the influence of rarefaction effect and misalignment. The results show that the rarefaction effect will decrease bearing load capacity compared with traditional solution of Reynolds equation, and the misalignment will reduce the stability of bearing. The influence of misalignment on gas film thickness is also analyzed in this paper. Originality/value The investigation of this paper emerges the change regularity of comprehensive performance of MEMS gas bearing considering rarefaction effect and misalignment, which provides a reference for the actual manufacturing of MEMS gas bearing and for the safety operation of micro dynamic machinery. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0023/

scholarly journals Mathematical Model and Analysis of the Water-Lubricated Hydrostatic Journal Bearings considering the Translational and Tilting Motions

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Hui-Hui Feng ◽  
Chun-Dong Xu ◽  
Jie Wan
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Journal Bearings ◽  
Linear Perturbation ◽  
Eccentricity Ratio ◽  
Dynamic Coefficients ◽  
Pressure Fields ◽  
Dynamic Performances ◽  
Rotary Speed

The water-lubricated bearings have been paid attention for their advantages to reduce the power loss and temperature rise and increase load capacity at high speed. To fully study the complete dynamic coefficients of two water-lubricated, hydrostatic journal bearings used to support a rigid rotor, a four-degree-of-freedom model considering the translational and tilting motion is presented. The effects of tilting ratio, rotary speed, and eccentricity ratio on the static and dynamic performances of the bearings are investigated. The bulk turbulent Reynolds equation is adopted. The finite difference method and a linear perturbation method are used to calculate the zeroth- and first-order pressure fields to obtain the static and dynamic coefficients. The results suggest that when the tilting ratio is smaller than 0.4 or the eccentricity ratio is smaller than 0.1, the static and dynamic characteristics are relatively insensitive to the tilting and eccentricity ratios; however, for larger tilting or eccentricity ratios, the tilting and eccentric effects should be fully considered. Meanwhile, the rotary speed significantly affects the performance of the hydrostatic, water-lubricated bearings.

Analysis on Dynamic Performance of Hydrodynamic Tilting-Pad Gas Bearings Using Partial Derivative Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Yang Lihua ◽  
Qi Shemiao ◽  
Yu Lie
Keyword(s):  
Analytical Method ◽  
Gas Turbines ◽  
High Speed ◽  
Dynamic Performance ◽  
Gas Bearings ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Dynamic Performances ◽  
Perturbation Frequency ◽  
San Andres

Tilting-pad gas bearings are widely used in high-speed rotating machines due to their inherent stability characteristics. This paper advances the analytical method for prediction of the dynamic performances of tilting-pad gas bearings. The main advantage of the analytical method is that the complete set of dynamic coefficients of tilting-pad gas bearings can be obtained. The predictions show that the perturbation frequency has the strong effects on the dynamic coefficients of gas bearings. In general, at lower perturbation frequency, the equivalent direct stiffness coefficients increase with frequency, whereas equivalent direct damping coefficients dramatically reduce. For higher perturbation frequency, the dynamic coefficients are nearly independent of the frequency. Moreover, the equivalent dynamic coefficients of four-pad tilting-pad gas bearing obtained by the method in this paper are in good agreement with those obtained by Zhu and San Andres [(2007), “Rotordynamic Performance of Flexure Pivot Hydrostatic Gas Bearings for Oil-Free Turbomachinery,” ASME J. Eng. Gas Turbines Power, 129(4), pp. 1020–1027] in the published paper. The results validate the feasibility of the method presented in this paper in calculating the dynamic coefficients of gas-lubricated tilting-pad bearings.

On the characteristics of gas foil conical bearings considering misalignment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Friction Torque ◽  
Misalignment Angle ◽  
Content Type ◽  
Stiffness Model ◽  
Dynamic Performances

Purpose The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied. Design/methodology/approach A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness. Findings The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance. Originality/value The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117

A high-speed rolling bearing test rig supported by sliding bearing

2020 ◽  
Vol 72 (7) ◽  
pp. 955-959
Author(s):  
Hui Li ◽  
Heng Liu ◽  
Shemiao Qi ◽  
Yi Liu
Keyword(s):  
Service Life ◽  
Peer Review ◽  
High Speed ◽  
Load Capacity ◽  
Rolling Bearing ◽  
Test Rig ◽  
Sliding Bearing ◽  
Content Type ◽  
Rotating Speed ◽  
Operating Stability

Purpose The purpose of this paper is to introduce a high-speed rolling bearing test rig supported by sliding bearing and its first experimental results. Design/methodology/approach Through analyzing the disadvantages of using rolling bearing as supporting bearing, the bottlenecks that need to be resolved urgently in the development of rolling bearing experimental technology, and the advantages of the sliding bearing, this study used the sliding bearing as the supporting bearing for the high-speed rolling bearing test rig for the purpose of prolonging the service life, increasing the load capacity and promoting the operating stability. Findings The experimental results show that the high-speed rolling bearing test rig supported by sliding bearing could stably rotate at 70,800 rpm without installing the test bearing; the temperature of the sliding bearing is increasing with the rotating speed and the maximum is less than 95°C. Moreover, the new test rig, installing an angular contact ball bearing as test bearing, could also stably rotate at 54,000 rpm with 2 kN axial load and 1 kN radial load; the temperature of the sliding bearing is increasing with the rotating speed and the maximum temperature is less than 97°C. Practical implications Rolling test rig has been established. Originality/value This paper proposes a high-speed rolling bearing test rig supported by sliding bearing, which greatly prolongs the service life, increases the load capacity and promotes the operating stability, moreover, reduces the risk of supporting bearing failure before the test bearing. This paper can also provide a new idea and reference for the design of similar bearing test rig. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0085/

scholarly journals Influence of Aerodynamic Preloads and Clearance on the Dynamic Performance and Stability Characteristic of the Bump-Type Foil Air Bearing

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 178
Author(s):  
Fabian Walter ◽  
Michael Sinapius
Keyword(s):  
High Speed ◽  
Transient Stability ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Stability Characteristic ◽  
Air Bearing ◽  
Operational Parameters ◽  
Positive Effects ◽  
Lift Off ◽  
The Stability

The dry lubricated bump-type foil air bearing enables a carrying load capacity due to a pressure build up in a convergent air film. Since the air bearing provides low power dissipation above the lift-off speed and the flexible foil provides an adaptivity against high temperatures, manufacturing errors or rotor growth, the bump-type foil air bearing is in particular suitable for high speed rotating machineries. The corresponding dynamic behavior depends on the operational parameters, the behavior of the flexible foil structure, and in particular on the circumferential clearance. In order to avoid or suppress the critical subsynchronous motion at high rotational speeds, many researchers recommend adding an aerodynamic preload to the bore shape, representing a transition from a circular to a lobed bearing bore shape. In addition to positive effects on the stability, preliminary studies demonstrated degrading effects on the stiffness and damping due to increasing preload values. This observation leads to the assumption, that the preload value meets an optimum with respect to stability, load-capacity, and lift-off speed. With the aim of deriving an appropriate lobe configuration for the design of the bump-type foil air bearing, this work performs comprehensive numerical investigations on the dynamic performance and the stability characteristic as a function of preload and minimum clearance. To this end, this work uses steady-state and transient stability analysis methods to recommend optimal aeroydnamic preload values with respect to the corresponding minimum clearance.

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