Search results

1 – 10 of 21
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 6 August 2019

Guo Xiang Guo Xiang, Yanfeng Han, Renxiang Chen, Jiaxu Wang Jiaxu Wang and Ni Xiaokang

This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings).

236

Abstract

Purpose

This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings).

Design/methodology/approach

The coupled hydrodynamic effect (or coupled effect) between the journal and the thrust bearing is considered by ensuring the continuity of the hydrodynamic pressure and the flow field at the common boundary. The mixed lubrication performances of the coupled bearing are comparatively studied for the cases of considering and not considering coupled effect.

Findings

The simulated results show that the hydrodynamic pressure distributions for both the journal and thrust bearing are modified due to the coupled effect. The decreased load capacity of the journal bearing and the increased load capacity of the thrust bearing can be observed when the coupled effect is considered. And the coupled effect can facilitate in reducing the asperity contact load for both the journal and thrust bearing. Additionally, the interaction between the mixed lubrication behaviors, especially for the friction coefficient, of the journal and the thrust bearing is significant in the elastohydrodynamic lubrication regime, while it becomes weak in the mixed lubrication regime.

Originality/value

The developed model can reveal the mutual effects of the mixed lubrication behavior between the journal and the thrust bearing.

Details

Industrial Lubrication and Tribology, vol. 71 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 27 July 2021

Xiaohuan Liu, Degan Zhang, Ting Zhang, Jie Zhang and Jiaxu Wang

To solve the path planning problem of the intelligent driving vehicular, this paper designs a hybrid path planning algorithm based on optimized reinforcement learning (RL) and…

807

Abstract

Purpose

To solve the path planning problem of the intelligent driving vehicular, this paper designs a hybrid path planning algorithm based on optimized reinforcement learning (RL) and improved particle swarm optimization (PSO).

Design/methodology/approach

First, the authors optimized the hyper-parameters of RL to make it converge quickly and learn more efficiently. Then the authors designed a pre-set operation for PSO to reduce the calculation of invalid particles. Finally, the authors proposed a correction variable that can be obtained from the cumulative reward of RL; this revises the fitness of the individual optimal particle and global optimal position of PSO to achieve an efficient path planning result. The authors also designed a selection parameter system to help to select the optimal path.

Findings

Simulation analysis and experimental test results proved that the proposed algorithm has advantages in terms of practicability and efficiency. This research also foreshadows the research prospects of RL in path planning, which is also the authors’ next research direction.

Originality/value

The authors designed a pre-set operation to reduce the participation of invalid particles in the calculation in PSO. And then, the authors designed a method to optimize hyper-parameters to improve learning efficiency of RL. And then they used RL trained PSO to plan path. The authors also proposed an optimal path evaluation system. This research also foreshadows the research prospects of RL in path planning, which is also the authors’ next research direction.

Details

Engineering Computations, vol. 39 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Access Restricted. View access options
Article
Publication date: 9 February 2022

Haiming Dai, Guo Xiang, Jiaxu Wang, Juan Guo, Cheng Wang and Hang Jia

The purpose of this study is to numerically investigate the time-varying mixed lubrication performance of microgroove journal-thrust coupled bearing (MJTCB) under nonlinear…

190

Abstract

Purpose

The purpose of this study is to numerically investigate the time-varying mixed lubrication performance of microgroove journal-thrust coupled bearing (MJTCB) under nonlinear excitation.

Design/methodology/approach

A three degree of freedom (3-DOF) dynamic model of the rotor coupling with the transient mixed lubrication behavior is established. Based on numerical predictions, the role of the microgroove on the time-varying mixed lubrication performance of MJTCB is identified. The effects of the microgroove depth, microgroove shape and external load on the time-varying mixed lubrication performance of MJTCB are also studied.

Findings

Numerical results show that the effect of the coupling hydrodynamic on the time-varying mixed lubrication performance of the coupled bearing is strengthen with the increasing of microgroove depth. Furthermore, it is found that the optimal microgroove shape for the thrust bearing, arc or rectangle, highly depends on the microgroove depth. Finally, the contact performance of the thrust bearing is slightly affected by the radial external load.

Originality/value

This study is expected to achieve a better understanding of the time-varying mixed lubrication performance of MJTCB under nonlinear excitations.

Details

Industrial Lubrication and Tribology, vol. 74 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 12 March 2018

Wei Pu, Jiaxu Wang, Guangwu Zhou, Ke Xiao and Junyang Li

The purpose of this study is to describe and observe the effect of surface topography associated with arbitrary directions of rolling and sliding velocities on the performance of…

264

Abstract

Purpose

The purpose of this study is to describe and observe the effect of surface topography associated with arbitrary directions of rolling and sliding velocities on the performance of lubricating films in elliptical contacts.

Design/methodology/approach

The most recently published mixed elastohydrodynamic (EHL) model by Pu and Zhu is used. Three different machined rough surfaces are discussed and the correlated inclined angle of surface velocity varies from 0° to 90° in the analyzed cases. These cases are carried out in a wide range of speeds (five orders of magnitude) while the simulated lubrication condition covers full-film and mixed EHL down to the boundary lubrication.

Findings

The results indicate that the variation of the average film thickness corresponding to different entrainment angles is distinct from those without considering surface roughness. In addition, the surface topography appears to have an immense effect on the lubrication film thickness in the exceptive situation.

Originality/value

This paper has not been published previously. Surface roughness has attracted much attention for many years owing to the significant influence on lubricating property. However, previous studies mainly focus on the counterformal contact with the same direction between surface velocity and principal axis of the contact zone. Little attention has been paid to the specific condition with the arbitrary direction of rolling and sliding velocities found in hypoid gears and worm, and some other components. The purpose of this study is to describe and observe the effect of surface topography associated with arbitrary directions of rolling and sliding velocities on the performance of lubricating films in elliptical contacts based on the most recently published mixed EHL model by Pu and Zhu.

Details

Industrial Lubrication and Tribology, vol. 70 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 13 August 2018

Guangwu Zhou, Xiongwei Mi, Jiaxu Wang and Rukang Hu

The research purpose of this paper is to obtain a transition process of lubrication condition of water-lubricated rubber bearing (WLRB) by investigating Stribeck curve of WLRB…

271

Abstract

Purpose

The research purpose of this paper is to obtain a transition process of lubrication condition of water-lubricated rubber bearing (WLRB) by investigating Stribeck curve of WLRB with either straight grooves or spiral grooves using a comparison experiment and providing guidance for structure optimization and application extension of WLRB.

Design/methodology/approach

This study tested the Stribeck curve of WLRB with either straight or spiral grooves using a comparison experiment; the variables used are rotary speed and external load.

Findings

Stribeck curves of WLRB with straight or spiral grooves under varied load are obtained with the experiments, and the speed turning points when the lubrication condition of WLRB transit are acquired. Research results indicate that the transition of the speed turning point for lubrication condition of WLRB with spiral grooves is smaller than that of WLRB with straight grooves. Besides, it was found that within the whole speed range, the friction coefficient of WLRB with straight grooves decreases with the increase in load under the same speed. However, Stribeck curves of WLRB with spiral grooves show that the coefficient increases first and then decreases with the increase in load and finally comes to a steady value. Under the same rotary speed and external load, the friction coefficient of WLRB with spiral grooves is smaller than that of WLRB with straight grooves, claiming that the WLRB with spiral grooves has better lubrication properties.

Originality/value

By testing the Stribeck curve of WLRB with straight grooves or spiral grooves using the comparison experiment, lubrication properties of the WLRB are obtained. The transition mechanism of the lubrication condition for WLRB is acquired, revealing the effects of speed and load on the lubrication property. The research offers a scientific basis for the structure optimization of WLRB.

Details

Industrial Lubrication and Tribology, vol. 70 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 13 November 2017

Wei Cao, Jiaxu Wang, Wei Pu, Ying Zhang, Jiqiang Wu, Si Ren and Jianbing Long

Previous studies were mainly focused on profile designation of bearing rollers and lubrication performance without considering roller-races skidding. However, the width of round…

265

Abstract

Purpose

Previous studies were mainly focused on profile designation of bearing rollers and lubrication performance without considering roller-races skidding. However, the width of round corner, load, rotational speed and some other parameters have significant effects on the roller-races sliding speed. This paper aims to investigate the effect of round corner on lubricating characteristics between the heavily loaded roller and inner race considering skidding and roughness.

Design/methodology/approach

A mixed elastohydrodynamic lubrication (EHL) model which is capable of handling practical cases with 3D machined roughness is combined with the skidding model to investigate the effect of round corner on lubricating characteristics between the heavily loaded roller and inner race.

Findings

The width of round corner and round corner radius have a desirable range under certain operating condition, within which the maximum pressure, stress and maximum flash temperature remain low. The optimized range is sensitive to the operating condition. Roughness and skidding narrow the optimized range of round corner radius. Roughness increases the pressure peak, Mises stress and friction coefficient. At the same time, skidding and roughness have obvious effects on film thickness at the contact center area if the round radius is small.

Research limitations/implications

This paper uses the Harris skidding model that has a relatively bigger error, which is not accurate if the bearing load is less.

Practical implications

This paper unifies the skidding model and mixed EHL model which can be used as a tool for optimization design and lubricating performance analysis of cylindrical roller bearing.

Originality/value

Lubrication analyses for roller bearing are assumed to be pure rolling contact between roller and races in a previous study, which could not reflect the real contact characteristics. The skidding model is merged into a mixed EHL model which can be used as a dynamic tool to analyze the lubricating performance considering the round corner, skidding and roughness.

Details

Industrial Lubrication and Tribology, vol. 69 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 8 January 2018

Zhenhua Zhang, Jiaxu Wang, Guangwu Zhou and Xin Pei

This paper aims to solve the lubrication failures in the turning arm bearing of RV reducer, give some help in perfecting the bearing structure design and provide theoretical basis…

447

Abstract

Purpose

This paper aims to solve the lubrication failures in the turning arm bearing of RV reducer, give some help in perfecting the bearing structure design and provide theoretical basis for the reducer’s performance improvement.

Design/methodology/approach

The paper establishes a mixed lubrication analysis model to study performance parameters. According to the discretization of parameters and iteration of equations, numerical simulation and theoretical analysis are achieved in computational process.

Findings

Considering influences of contact load, real rough surface and realistic geometry of RV reducer turning arm roller bearing, the mixed lubrication analysis model is established to study the ratio of oil film thickness, pressure distribution and maximum von Mises stress in different speeds, temperatures and fillets. The results of mixed lubrication show that reasonable round corner modification, increase in temperature and speed, decrease of surface roughness and lubricant types can improve the lubrication performance.

Originality/value

The mixed lubrication analysis model is established to study the influences of contact load, real rough surface and realistic geometry of RV reducer turning arm roller bearing. Different speed, temperature, lubricant and fillet modification are also considered in the research to analyze oil film thickness, pressure distribution and maximum von Mises stress. These studies can optimize structural design of bearing and direct engineer operations.

Details

Industrial Lubrication and Tribology, vol. 70 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 21 November 2018

Yong Yang, Wenguang Li, Jiaxu Wang and Qinghua Zhou

The purpose of this study is to investigate the tribological performance of helical gear pairs with consideration of the properties of non-Newtonian lubricant and the real…

451

Abstract

Purpose

The purpose of this study is to investigate the tribological performance of helical gear pairs with consideration of the properties of non-Newtonian lubricant and the real three-dimensional (3D) topography of tooth flanks.

Design/methodology/approach

Based on the mixed elastohydrodynamic lubrication (EHL) theory for infinite line contact, this paper proposes a complete model for involute helical gear pairs considering the real 3D topography of tooth flanks and the properties of non-Newtonian lubricant. Film thickness, contact load and contact area ratios at the mid-point of contact line are studied for each angular displacement of pinion. Both the total friction coefficient and surface flash temperature are calculated after obtaining the values of pressure and subsurface stress. Then, the influences of input parameters including rotational speed and power are investigated.

Findings

During the meshing process, contact load ratio and area ratio of the two rough surface cases first increase and then decrease; the maximum flash temperature rise (MFTR) on the gear is lower than that on the pinion first, but later the situation converses. For cylindrical gears, on the plane of action, there is a point or a line where the instantaneous friction reduces to a minimum value in a sudden, as the sliding–rolling ratio becomes zero. When rotational speed increases, film thickness becomes larger, and meanwhile, contact load ratio, coefficient of friction and MFTR gradually reduce.

Originality/value

A comprehensive analysis is conducted and a computer program is developed for meshing geometry, kinematics, tooth contact, mixed EHL characteristics, friction, FTR and subsurface stress of involute helical gear pairs. Besides, a numerical simulation model is developed, which can be used to analyze mixed lubrication with 3D machined roughness under a wide range of operating conditions.

Details

Industrial Lubrication and Tribology, vol. 71 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 6 August 2020

Wei Feng, Lei Yin, Yanfeng Han, Jiaxu Wang, Ke Xiao and Junyang Li

This paper aims to explore the possibility of converting the nitrile butadiene rubber (NBR) water-lubricated bearing material into a self-lubricating bearing material by the…

296

Abstract

Purpose

This paper aims to explore the possibility of converting the nitrile butadiene rubber (NBR) water-lubricated bearing material into a self-lubricating bearing material by the action of polytetrafluoroethylene (PTFE) particles and water lubrication.

Design/methodology/approach

A group of experimental studies was carried out on a ring-on-block friction test. The physical properties, tribological properties and interface structure of PTFE-NBR self-lubricating composites filled with different percentages of PTFE particles were investigated.

Findings

The experimental results indicated that the reduction in friction and wear is a result of the formation of the lubricating film on the surface of the composites. The lubricating film was formed of a large amount of PTFE particles continuously supplied under water lubrication conditions and the PTFE particles here can greatly enhance the load capacity and lubrication performance.

Originality/value

In this study, the tribological properties of PTFE particles added to the NBR water-lubricated bearing materials under water lubrication were investigated experimentally, and the research was carried out by a ring-on-block friction test. It is believed that this study can provide some guidance for the application of PTFE-NBR self-lubricating.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0187/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 13 August 2024

Xiaohui Xiong, Jiaxu Geng, Kaiwen Wang and Xinran Wang

This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method…

86

Abstract

Purpose

This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof.

Design/methodology/approach

The improved delayed detached eddy simulation method based on shear stress transport k-ω turbulence model has been used to conduct computational fluid dynamics simulation on the train with three different wing height layouts, at a Reynolds number of 2.8 × 106. The accuracy of the numerical method has been validated by wind tunnel experiments.

Findings

The wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights.

Originality/value

This paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 10
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of 21
Per page
102050