Research

15 pages, 13301 KiB

Open AccessArticle

Pivot Stiffness Effect on Transient Dynamic Characteristic of Tilting Pad Journal Bearing-Rotor System Passing through Critical Speed

by Yingze Jin, Qiuli Niu, Yuanpeng Qu and Xiaoyang Yuan

Lubricants 2023, 11(3), 125; https://doi.org/10.3390/lubricants11030125 - 10 Mar 2023

Cited by 2 | Viewed by 1306

Abstract

Tilting pad journal bearings (TPJBs) are widely applied in the high-speed rotor system whose working speed is higher than its critical speed due to excellent hydrodynamic lubrication and stability. Pivot stiffness is one of the key design parameters of TPJBs compared to other [...] Read more.

Tilting pad journal bearings (TPJBs) are widely applied in the high-speed rotor system whose working speed is higher than its critical speed due to excellent hydrodynamic lubrication and stability. Pivot stiffness is one of the key design parameters of TPJBs compared to other journal bearings and has become particularly important for optimizing the performance of TPJB-rotor systems. In order to improve the vibration and critical characteristics of rotor systems, the transient dynamic characteristic of a TPJB-rotor system passing through the critical speed is investigated considering different pivot stiffness ratios. A time-varying dynamics model of a symmetrical single-disc rotor supported by four-pad TPJBs is established considering constant acceleration conditions and nonlinear hydrodynamic bearing force. The disc vibration characteristic, journal vibration characteristic, pad vibration characteristic, and hydrodynamic bearing force are analyzed by using Bode plot, shaft center orbit, pad phase orbit, waterfall plot, and time history. The results show that the pivot stiffness plays a major role in the suppression of resonance amplitude and working amplitude of a TPJB-rotor system, without changing the frequency characteristic of the system. This study provides a theoretical basis for the pivot stiffness design of TPJBs and the vibration suppression of rotor systems. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

17 pages, 10116 KiB

Open AccessArticle

Study on the Friction Characteristics and Fatigue Life of Manganese Phosphate Coating Bearings

by Lijie Hao, Yong Chen, Guangxin Li, Min Zhang, Yimin Wu, Rui Liu and Guang Chen

Lubricants 2023, 11(3), 99; https://doi.org/10.3390/lubricants11030099 - 26 Feb 2023

Cited by 1 | Viewed by 1337

Abstract

In this study, the tapered roller bearing was adopted to explore the effect of the manganese phosphate coating on the friction, wear, and lifespan of bearings. Line friction samples with and without a manganese phosphate coating were prepared. The White Light Interferometry was [...] Read more.

In this study, the tapered roller bearing was adopted to explore the effect of the manganese phosphate coating on the friction, wear, and lifespan of bearings. Line friction samples with and without a manganese phosphate coating were prepared. The White Light Interferometry was used to analyze the three-dimensional morphology and roughness, and the Optimal Schwing–Reib–Verschleiss-5 multifunctional friction and wear tester was applied to obtain the tribological parameters before and after the application of the manganese phosphate coating. A scanning electron microscopy and energy dispersive spectrometry were used to characterize the microstructure and element composition of the worn surfaces of the manganese phosphate coating. The influence of the manganese phosphate coating on the contact stress was contrasted and examined by establishing a finite element model of the tapered roller bearing. Finally, a life test of the tapered roller bearings was performed before and after the application of the manganese phosphate coating. The results demonstrate that manganese phosphate coating enhances wear resistance, lowers bearing contact stress, and reduces the coefficient of friction. The fatigue life of the tapered roller bearing can be significantly extended with a manganese phosphate coating. This is a new method that can be used to improve the service life of bearings. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

11 pages, 4701 KiB

Open AccessArticle

High-Precision Flow Field Simulation of Aerostatic Bearings Based on the Interior Penalty Discontinuous Galerkin Method

by Weijie Hou, Qiushi Ding, Yongbo Hao, Jingshuo Cao, Shixi Hao, Kai Feng and Ming Zhao

Lubricants 2022, 10(12), 360; https://doi.org/10.3390/lubricants10120360 - 13 Dec 2022

Cited by 1 | Viewed by 1162

Abstract

All the static performance, dynamic characteristics, and stability are strongly associated with the flow field inside the aerostatic bearings. Therefore, a high-precision numerical method is beneficial for the detailed description of the bearing flow field. To this end, a modified interior penalty discontinuous [...] Read more.

All the static performance, dynamic characteristics, and stability are strongly associated with the flow field inside the aerostatic bearings. Therefore, a high-precision numerical method is beneficial for the detailed description of the bearing flow field. To this end, a modified interior penalty discontinuous Galerkin method was introduced here. Actually, a lift operator was included to eliminate the so-called homogeneity tensor connecting the viscous term and variable gradient, which could improve the numerical feasibility. The accuracy of the above numerical method has been comprehensively validated through viscous cases, including Couette flow and shear-driven cavity flow. Then, the flow fields of three aerostatic bearings were simulated with different orifice geometries. As a result, the Mach number distributions and static pressure could be estimated together with the integration of the pressure acting upon the thrust surface. The acceleration within the orifice and air film could be detected, and the influence of the orifice geometry has been systematically discussed. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

19 pages, 7365 KiB

Open AccessArticle

Dry Sliding Wear Features of an Al-20Sn-5Zn Alloy Affected by Microstructural Length Scales

by André Barros, Clarissa Cruz, Tamires Botelho, Adrina Silva, Luiz Casteletti, Amauri Garcia and Noé Cheung

Lubricants 2022, 10(12), 352; https://doi.org/10.3390/lubricants10120352 - 05 Dec 2022

Cited by 2 | Viewed by 1201

Abstract

Al-Sn-Zn alloys are attractive options for use as wear-resistant materials. While Sn promotes self-lubricating characteristics, Zn strengthens the Al-rich matrix. Conventionally, the manufacturing of these alloys involves casting. However, there is still a paucity of studies that associate the solidification microstructure with the [...] Read more.

Al-Sn-Zn alloys are attractive options for use as wear-resistant materials. While Sn promotes self-lubricating characteristics, Zn strengthens the Al-rich matrix. Conventionally, the manufacturing of these alloys involves casting. However, there is still a paucity of studies that associate the solidification microstructure with the wear resistance of these alloys. Inspired by such considerations, this work aims at investigating the wear behavior of an Al-20Sn-5Zn [wt.%] alloy produced by a directional solidification technique. A set of samples with different microstructure length scales was subjected to ball cratering tests using a normal contact load of 0.25 N and six test times. The results show that the dependence of the wear behavior on the microstructure length scale becomes more expressive for longer sliding distances. It was found that coarser microstructures provide an improved wear resistance. In view of that, a possible spectrum of specific wear rates was determined as a function of the sliding distance, considering different microstructure length scales. Finally, experimental equations are proposed to represent a possible range of wear volume and wear coefficient according to the dendrite arm spacings. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Graphical abstract

25 pages, 14593 KiB

Open AccessArticle

Influence of Structural and Operating Parameters on Lubrication Performance of Water-Lubricated Polymer Bearing with Journal Misalignment

by Fangrui Lv, Chunxiao Jiao, Qian Jia and Kang Xia

Lubricants 2022, 10(12), 336; https://doi.org/10.3390/lubricants10120336 - 28 Nov 2022

Cited by 4 | Viewed by 1516

Abstract

Marine water-lubricated polymer bearings support the propeller shaft that stretches out of the ship. The bending deformation of propeller shaft often leads to journal misalignment, significantly impacting the bearing performance. In this paper, a mixed lubrication model for water-lubricated polymer bearing is established [...] Read more.

Marine water-lubricated polymer bearings support the propeller shaft that stretches out of the ship. The bending deformation of propeller shaft often leads to journal misalignment, significantly impacting the bearing performance. In this paper, a mixed lubrication model for water-lubricated polymer bearing is established considering the effect of journal misalignment, liner elastic deformation, and local turbulence. The influence of key structural and operating parameters on the performance of water-lubricated bearing with journal misalignment is investigated. The results show that the journal misalignment significantly reduces the load-carrying capacity, deteriorates the bearing tribological characteristics, and may cause different axial sections of the bearing to be in different lubrication regimes. Compared with aligned bearings, increasing the length–diameter ratio to improve the load-carrying capacity is significantly weakened for misaligned bearings. Increasing the liner thickness and the load improves axial uniformity of pressure distribution of misaligned bearings. A relatively large clearance ratio decreases the load-carrying capacity and increases the friction coefficient of bearings in the mixed lubrication regime. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

17 pages, 5890 KiB

Open AccessArticle

Evaluation and Application of an Engineering Calculation Method of the Static Performance of an Aerostatic Journal Bearing with Multiple Orifice-Type Restrictors

by Yangong Wu, Zheng Qiao, Wentao Chen, Jiadai Xue and Bo Wang

Lubricants 2022, 10(12), 332; https://doi.org/10.3390/lubricants10120332 - 24 Nov 2022

Cited by 1 | Viewed by 1427

Abstract

A simplified calculation method is evaluated to calculate the static performance of an aerostatic journal bearing with multiple orifice-type restrictors. This method adopts a one-dimension flow assumption and is a fast calculation method to design journal bearings in engineering by directly linking the [...] Read more.

A simplified calculation method is evaluated to calculate the static performance of an aerostatic journal bearing with multiple orifice-type restrictors. This method adopts a one-dimension flow assumption and is a fast calculation method to design journal bearings in engineering by directly linking the structural parameters and performance parameters affecting radial bearings with nonlinear equations. In addition, this method is verified with computational fluid dynamics by two actual case studies, and it is found that the LCC difference between those two methods is less than 5% for a 200 mm diameter spindle, and less than 10% for a 100 mm diameter spindle. Subsequently, the influence of a key parameter

ζ_{i}

on the static performance of journal bearings is explained theoretically. This method is much easier and more intuitive compared with numerical computational methods. Furthermore, it promotes the application of aerostatic journal bearings. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

21 pages, 16190 KiB

Open AccessArticle

A New Approach for the Load Calculation of the Most-Loaded Rolling Element of the Rolling Bearing with Internal Radial Clearance—A Case Study

by Radoslav Tomović

Lubricants 2022, 10(11), 306; https://doi.org/10.3390/lubricants10110306 - 12 Nov 2022

Cited by 1 | Viewed by 1157

Abstract

One of the most important factors influencing the study of the tribological behaviour of a rolling bearing is the calculation of the loads transmitted by individual rolling elements of the bearing. However, the calculation of the internal load distribution of rolling bearings is [...] Read more.

One of the most important factors influencing the study of the tribological behaviour of a rolling bearing is the calculation of the loads transmitted by individual rolling elements of the bearing. However, the calculation of the internal load distribution of rolling bearings is quite complicated. It is a nonlinear, statically indeterminate problem, which can only be solved numerically, through a number of iterations. This is often a problem in analysis because it complicates the mathematical model. This paper is presenting a case study with the goal to show the benefits of the application of a new approach for the calculation of the load of the most-loaded rolling element in the rolling bearing with the internal radial clearance. The calculation is based on the so-called load factors. By multiplying the load factors with the value of the external radial load, the load that is transferred by the most-loaded rolling element of the bearing is obtained. The accuracy of the results largely depends on the correct choice of the load factor. The case study aims to define guidelines for the correct choice of load factors. The case study is made for two types of bearings: the ball bearing and the roller bearing. Obtained results were compared with the results obtained based on the calculation using some of the most commonly used methods so far. The analysis showed greater precision of the considered model with the same or much simpler use. For this reason, the proposed model is considered very suitable for practical application. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

19 pages, 5341 KiB

Open AccessArticle

Static and Dynamic Characteristics of Rough Porous Rayleigh Step Bearing Lubricated with Couple Stress Fluid

by Neminath Naduvinamani and Ashwini Angadi

Lubricants 2022, 10(10), 257; https://doi.org/10.3390/lubricants10100257 - 13 Oct 2022

Cited by 4 | Viewed by 1273

Abstract

In tribology, the Rayleigh step bearing has the maximum load capacity of any feasible bearing geometry. Traditional tribology resources have demonstrated that the Rayleigh step has an ideal geometry which maximizes load capacity. Both in nature and technology, rough and textured surfaces are [...] Read more.

In tribology, the Rayleigh step bearing has the maximum load capacity of any feasible bearing geometry. Traditional tribology resources have demonstrated that the Rayleigh step has an ideal geometry which maximizes load capacity. Both in nature and technology, rough and textured surfaces are essential for lubrication. While surface roughness enhances the performance of the bearings as an efficiency measure, it still has a significant impact on the load-carrying capacity of the bearing. In the present study, we investigate the dynamic characteristics of the Rayleigh step bearing with the impact of surface roughness and a porous medium by considering a squeezing action. Couple stress fluid is considered a lubricant with additives in both the film as well as the porous region. Based on Stokes constitutive equations for couple stress fluids, Darcy’s law for porous medium, and stochastic theory for rough surfaces, the averaged Reynolds-type equation is derived. Expressions are obtained for the volume flow rate, steady-state characteristics, and dynamic characteristics. The influence of surface roughness and the porous medium on the Rayleigh step bearing is analyzed. We investigated the static and dynamic characteristics of the Rayleigh step bearing. As a result, the couple stress fluid increases (decreases) the steady load-carrying capacity, dynamic stiffness, and dynamic damping coefficients, and decreases (increases) the volume flow rate negatively (positively) skewed roughness in comparison with that of the Newtonian case. The results are compared with those of the smooth case. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

16 pages, 7358 KiB

Open AccessArticle

Simulation and Experimental Verification of Dynamic Characteristics on Gas Foil Thrust Bearings Based on Multi-Physics Three-Dimensional Computer Aided Engineering Methods

by Tai-Yuan Yu and Pei-Jen Wang

Lubricants 2022, 10(9), 222; https://doi.org/10.3390/lubricants10090222 - 14 Sep 2022

Cited by 4 | Viewed by 2022

Abstract

This paper presents a method to simulate the dynamic operating characteristics of a gas foil thrust bearing based on linear elastic support and constant ambient temperature to mimic the transient structure–fluid interactions. In the physical model, the top and bump foils are simply [...] Read more.

This paper presents a method to simulate the dynamic operating characteristics of a gas foil thrust bearing based on linear elastic support and constant ambient temperature to mimic the transient structure–fluid interactions. In the physical model, the top and bump foils are simply represented by an infinite number of Hookean springs attached to a solid wall with a small amount of deformation, whereas the gas film in the bearing is under quasi-steady lubrication flow conditions with hydrodynamic pressure distributed on the little-deformed top foil. A three-dimensional multi-physics model in a cylindrical coordinate system is established via a commercial computer-aided engineering software package to predict the nominal dynamic characteristics of the gas foil thrust bearing. To verify the multi-physics model, an experimental bench was built in-house to measure the thrust force on the support of the bearing. With the pertinent bearing parameters being entered into the package, the simulations agree well with the experimental thrust forces. As a further step, a simulation model of a clamped-rotor gas foil thrust bearing design was thoroughly investigated under nominal operating conditions, resulting in predictions of underdamped oscillations in rotor motions. The phenomenon could be described using a linear mass–spring–damper model that is dependent on the gas film thickness. The stiffness and damping coefficients could serve as a base reference for rotor dynamics analysis. This concludes the potential development of a digital twin for gas foil thrust bearing systems. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Graphical abstract

39 pages, 12268 KiB

Open AccessArticle

Influence of Counter Surface Roughness and Lay on the Tribological Behaviour of Self-Lubricating Bearing Materials in Dry Sliding Conditions at High Contact Pressures

by Maria Rodiouchkina, Kim Berglund, Fredrik Forsberg, Ilia Rodushkin and Jens Hardell

Lubricants 2022, 10(8), 167; https://doi.org/10.3390/lubricants10080167 - 22 Jul 2022

Cited by 1 | Viewed by 2038

Abstract

In Kaplan turbines, the most critical components are the self-lubricating polymer composite bearings used to control the guide vanes and the turbine blades. Reducing the sliding wear and friction of these bearings can benefit both the economy and the environment, including longer useful [...] Read more.

In Kaplan turbines, the most critical components are the self-lubricating polymer composite bearings used to control the guide vanes and the turbine blades. Reducing the sliding wear and friction of these bearings can benefit both the economy and the environment, including longer useful life, lower operational costs, and higher efficiency. In this study, the influence of stainless-steel counter surface roughness and lay on the tribological behaviour of three bearing materials used in hydropower applications were investigated using a linear reciprocating flat-on-flat configuration under high contact pressure and low sliding speed. The surface roughness was measured using white light interferometry. SEM and EDS analysis were used to investigate the worn surfaces. Results from this study show that overly smooth surfaces result in higher friction and wear of the counter surface, while rougher surfaces have a negative effect on the wear of the polymers. Highest surface coverage using protective transfer layers is found on the steel surfaces with the perpendicular lay and is accompanied with a lower coefficient of friction compared to the parallel lay. The dominant wear mechanism of the bearing materials changes from delamination wear to abrasive wear between the lowest and the intermediate roughness for steel surfaces with the parallel lay. It can be concluded that counter surface topography has a significant influence on the tribological behaviour of these bearing materials and that the effect differs between the self-lubricating polymer composites. Full article

(This article belongs to the Special Issue Tribological Characteristics of Bearing System)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Tribological Characteristics of Bearing System

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Related Special Issue

Published Papers (10 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI