Search results

1 – 10 of 651
Article
Publication date: 25 June 2020

Wujiu Pan, Xiaopeng Li and Xue Wang

The purpose of this paper is to provide a static friction coefficient prediction model of rough contact surfaces based on the contact mechanics analysis of elastic-plastic fractal…

Abstract

Purpose

The purpose of this paper is to provide a static friction coefficient prediction model of rough contact surfaces based on the contact mechanics analysis of elastic-plastic fractal surfaces.

Design/methodology/approach

In this paper, the continuous deformation stage of the multi-scale asperity is considered, i.e. asperities on joint surfaces go through three deformation stages in succession, the elastic deformation, the elastic-plastic deformation (the first elastic-plastic region and the second elastic-plastic region) and the plastic deformation, rather than the direct transition from the elastic deformation to the plastic deformation. In addition, the contact between rough metal surfaces should be the contact of three-dimensional topography, which corresponds to the fractal dimension D (2 < D < 3), not two-dimensional curves. So, in consideration of the elastic-plastic deformation mechanism of asperities and the three-dimensional topography, the contact mechanics of the elastic-plastic fractal surface is analyzed, and the static friction coefficient nonlinear prediction model of the surface is further established.

Findings

There is a boundary value between the normal load and the fractal dimension. In the range smaller than the boundary value, the normal load decreases with fractal dimension; in the range larger than the boundary value, the normal load increases with fractal dimension. Considering the elastic-plastic deformation of the asperity on the contact surface, the total normal contact load is larger than that of ignoring the elastic-plastic deformation of the asperity. There is a proper fractal dimension, which can make the static friction of the contact surface maximum; there is a negative correlation between the static friction coefficient and the fractal scale coefficient.

Originality/value

In the mechanical structure, the research and prediction of the static friction coefficient characteristics of the interface will lay a foundation for the understanding of the mechanism of friction and wear and the interaction relationship between contact surfaces from the micro asperity-scale level, which has an important engineering application value.

Details

Engineering Computations, vol. 38 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 4 July 2018

Yunlong Jiao, Xiaojun Liu and Kun Liu

Dynamic spreading and wetting on the rough surfaces is complicated, which directly affects the fluxion and phrase transition properties of the fluid. This paper aims to enhance…

Abstract

Purpose

Dynamic spreading and wetting on the rough surfaces is complicated, which directly affects the fluxion and phrase transition properties of the fluid. This paper aims to enhance our knowledge of the mechanism of micro-texture lubrication from interface wettability and provide some guidance for the practical manufacturing of the surfaces with special wettability and better lubrication characteristics.

Design/methodology/approach

The effect of surface topography on the wetting behavior of both smooth and rough hydrophilic surfaces was investigated using a combination of experimental and simulation approaches. Four types of patterns with different topographies were designed and fabricated through laser surface texturing. The samples were measured with a non-contact three-Dimensional (3D) optical profiler and were parameterized based on ISO 25178. Quantitative research on the relevancy between the topography characteristic and wettability was conducted with several 3D topography parameters.

Findings

Results show that for the surfaces with isotropic textures, topography with a small skewness (Ssk) and a large kurtosis (Sku) exhibits better wettability and spreading behavior. For the surfaces with anisotropic textures (smaller texture aspect ratio, Str), dominant textures (such as long groove, rectangle) play a significant guiding role in promoting spreading. In addition, the moving mechanism of the triple contact line and anisotropic spreading were also studied using a computational fluid dynamics simulation. The simulation results have a good adherence with the experimental results.

Originality/value

Most of the surface characterization methods at present remain at a level that is related to geometric description, and the topography parameters are limited to 2D roughness parameters. So in present study, the relevancy between wettability and 3D surface topography parameters is explored. The authors believe that the current work provides a new viewpoint to the relevancy between surface topography and wettability.

Details

Industrial Lubrication and Tribology, vol. 70 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 14 October 2019

Ligang Zhao, Guofeng Xia, Yuhu Shi and Aisheng Wu

The purpose of this paper is to study the influence of the processing parameters of diamond wire sawing on surface morphology and roughness.

Abstract

Purpose

The purpose of this paper is to study the influence of the processing parameters of diamond wire sawing on surface morphology and roughness.

Design/methodology/approach

First, a wire saw cutting model is established to determine the positional relationship between a wire saw and the machined surface of the workpiece, and the abrasive grain cutting trajectory is generated. Through the data processing of the cutting trajectory, the simulation of the three-dimensional surface topography of the slice and the calculation of the surface roughness are realized by using the GUI programming of MATLAB. Finally, different surface roughness values are obtained by changing the machining parameters (saw wire speed and workpiece feed speed).

Findings

The conclusion is that the surface roughness of the slice is larger when the feed speed is higher and smaller when the linear speed is higher.

Originality/value

Diamond wire saw cutting is the first process of chip processing, and its efficiency and quality have an important impact on subsequent processing. This paper will focus on the influence of the sawing wire cutting processing parameters (sawing wire speed and workpiece feed speed) on the surface roughness to optimize the processing parameters and obtain smaller surface roughness values. Through MATLAB three-dimensional simulation, the surface morphology can be observed more intuitively, which provides a theoretical basis for improving the processing quality.

Details

Industrial Lubrication and Tribology, vol. 72 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 January 2024

Shi Chen, Zhiyong Han, Qiang Zeng, Bing Wang, Liming Wang, Liuyang Guo and Yimin Shao

Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance…

73

Abstract

Purpose

Hydro-viscous drive (HVD) clutches are widely used in equipment requiring soft start, such as fans and pumps, to transmit torque and adjust speed by changing the gap distance between friction pairs. This paper aims to propose a novel two-parameter evaluation method for HVD during the mixed lubrication stage. The objective is to develop an effective model that establishes the relationship between these parameters and the actual surface topography.

Design/methodology/approach

In the presented methods, the fractal features of the real manufacturing surface are calculated based on the power spectrum function by the ultra-depth three-dimensional microscope. After that, the hybrid friction model of the friction plate is established based on mixed elasto-hydrodynamic lubrication theory, boundary friction model and fractal theory. Then the torque and load bearing characteristics of the clutch are obtained, and the influences of the surface fractal features are investigated and discussed. Finally, the Weierstrass–Mandelbrot function is adopted for the surface topography characterization and evaluation.

Findings

The results indicate that the proposed method exhibits good accuracy, while the speed difference between the friction pair exceeds 2,500 rpm. It is concluded that this paper proposed a way to evaluate the torque and loading capacity of HVD considering the real manufacturing surface topography and is helpful for surface optimization.

Originality/value

The originality and value of this study lie in its development of a novel torque and load bearing capacity evaluation method for HVD in mixed lubrication stage, considering manufacturing surface topography and describing the real manufacturing surface.

Details

Industrial Lubrication and Tribology, vol. 76 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 4 February 2014

Chen Wengang, Ge Shirong, Pang Lianyun and Zhang Yonghai

Three types of pattern on the monocrystalline silicon surface were prepared by using laser surface processing equipment. The DLC film and Si-DLC film on the patterning surface…

Abstract

Purpose

Three types of pattern on the monocrystalline silicon surface were prepared by using laser surface processing equipment. The DLC film and Si-DLC film on the patterning surface were deposited by using PECVD-2D plasma chemical vapor deposition sets. The paper aims to discuss these issues.

Design/methodology/approach

The tribological properties of the films were investigated by using the UMT-2 micro friction and wear tester. The surface topography, composition, hardness and elastic modular of the films were determined by Raman spectrum, nano mechanics tester and three-dimensional topography instrument. The worn surface topographies of the surface patterning films were tested by scanning electron microscopy.

Findings

The results show that the patterning monocrystalline silicon substrate surface has good anti-friction property under low load. The patterning DLC film and Si-DLC film surface have very good anti-friction property under all the test loads. The reason of these results is that the surface patterning film not only reduces the real contact area of the friction pairs but also has low surface bonding force.

Originality/value

This paper prepared three kinds of microscopic patterns on the monocrystalline silicon surface by using laser surface processing equipment. And then deposited DLC film and Si-DLC film on the patterning surface. All kinds of surface patterning monocrystalline silicon had very good anti-friction property under low load. And all kinds of surface patterning nano-hard film had perfect anti-friction property under all test loads.

Details

Industrial Lubrication and Tribology, vol. 66 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 17 January 2020

Qingchao Sun, Xin Liu, Xiaokai Mu and Yichao Gao

This paper aims to study the relationship between normal contact stiffness and contact load. It purpose a new calculation model of the normal contact stiffness of joint surfaces…

Abstract

Purpose

This paper aims to study the relationship between normal contact stiffness and contact load. It purpose a new calculation model of the normal contact stiffness of joint surfaces by considering the elastic–plastic critical deformation change of asperities contact.

Design/methodology/approach

The paper described the surface topography of joint surfaces based on fractal geometry, and fractal parameters and of fractal function derived from measurement data. According to the plastic–elastic contact theory, the contact deformation characteristic of asperities was analyzed; the critical deformation estimation model was presented, which expressed critical deformation as the function of fractal parameters and contact deformation; the contact stiffness calculation model of single asperity was brought forward by considering critical deformation change.

Findings

The paper combined the surface topography description function, analyzed the asperity contact states by considering the critical deformation change, and calculated normal contact stiffness based on fractal theory and contact deformation analysis. The comparison between theoretical contact stiffness and experimental data indicated that the theoretical normal contact stiffness agreed with the experimental data, and the estimation model for normal contact stiffness was appropriate.

Research limitations/implications

Owing to the possibility of plastic deformation during the loading process, the experimental curve between the contact stiffness and the contact load is nonlinear, resulting in an error between the experimental results and the theoretical calculation results.

Originality/value

The paper established the relationship between critical deformation and fractal surface topography by constructing asperity distribution function. The paper proposed a new normal contact stiffness calculation model of joint surfaces by considering the variation of critical deformation in contact process.

Details

Assembly Automation, vol. 40 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

Article
Publication date: 8 March 2011

Sudipto Ray and S.K. Roy Chowdhury

Although dependence of contact surface temperatures between rough sliding bodies on surface topography is more explicitly described in terms of three‐dimensional (3D) topographic…

Abstract

Purpose

Although dependence of contact surface temperatures between rough sliding bodies on surface topography is more explicitly described in terms of three‐dimensional (3D) topographic parameters, no work has yet been reported on this aspect. The paper seeks to carry out experiments to systematically correlate the 3D surface parameters to the contact temperature rise.

Design/methodology/approach

The surface temperatures at the contact between a relatively smooth zinc sulphide pin held against a rotating mild steel disc of varying surface topography were measured using an infrared thermal imaging system under different load and sliding velocity conditions. The main objective was to study the effect of 3D surface roughness parameters on the contact temperature rise.

Findings

The results indicate a rise in maximum contact temperature with the increase in a number of 3D parameters, such as, average surface roughness Sa, ten‐point height parameter Sz, skewness of the surface height distribution Ssk, mean summit curvature Ssc, and developed interfacial area ratio parameter Sdr while temperature was found to decrease with increasing values of another set of parameters, such as, kurtosis of the 3D surface texture Sku, summit density of the surface Sds, surface bearing index Sbi, core fluid retention index Sci, valley fluid retention index Svi, and root mean square slope of the surface Sdq.

Practical implications

In any sliding system, with mixed or boundary lubricated conditions, it can be attempted to find the optimum value of the roughness parameters so that on suitable processing of the surfaces a lower contact temperature rise can be achieved.

Originality/value

No work has yet been reported on the effect of 3D roughness parameters on contact temperature.

Details

Industrial Lubrication and Tribology, vol. 63 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 8 January 2024

Zhicai Du, Qiang He, Hengcheng Wan, Lei Zhang, Zehua Xu, Yuan Xu and Guotao Li

This paper aims to improve the tribological properties of lithium complex greases using nanoparticles to investigate the tribological behavior of single additives (nano-TiO2 or…

Abstract

Purpose

This paper aims to improve the tribological properties of lithium complex greases using nanoparticles to investigate the tribological behavior of single additives (nano-TiO2 or nano-CeO2) and composite additives (nano-TiO2–CeO2) in lithium complex greases and to analyze the mechanism of their influence using a variety of characterization tools.

Design/methodology/approach

The morphology and microstructure of the nanoparticles were characterized by scanning electron microscopy and an X-ray diffractometer. The tribological properties of different nanoparticles, as well as compounded nanoparticles as greases, were evaluated. Average friction coefficients and wear diameters were analyzed. Scanning electron microscopy and three-dimensional topography were used to analyze the surface topography of worn steel balls. The elements present on the worn steel balls’ surface were analyzed using energy-dispersive spectroscopy and X-ray photoelectron spectroscopy.

Findings

The results showed that the coefficient of friction (COF) of grease with all three nanoparticles added was low. The grease-containing composite nanoparticles exhibited a lower COF and superior anti-wear properties. The sample displayed its optimal tribological performance when the ratio of TiO2 to CeO2 was 6:4, resulting in a 30.5% reduction in the COF and a 29.2% decrease in wear spot diameter compared to the original grease. Additionally, the roughness of the worn spot surface and the maximum depth of the wear mark were significantly reduced.

Originality/value

The main innovation of this study is the first mixing of nano-TiO2 and nano-CeO2 with different sizes and properties as compound lithium grease additives to significantly enhance the anti-wear and friction reduction properties of this grease. The results of friction experiments with a single additive are used as a basis to explore the synergistic lubrication mechanism of the compounded nanoparticles. This innovative approach provides a new reference and direction for future research and development of grease additives.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2023-0291/

Details

Industrial Lubrication and Tribology, vol. 76 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 10 August 2018

Jun Wu and Zhangcan Huang

As the internal defects (pore defect) of materials formed during the preparation of the composite material have important effects on wear process, the model has been improved to…

Abstract

Purpose

As the internal defects (pore defect) of materials formed during the preparation of the composite material have important effects on wear process, the model has been improved to simulate it.

Design/methodology/approach

Materials with defects were simulated by an improved cellular automaton model which show changes in three-dimensional topography, temperature of surface and coefficient of friction (COF) during wear process.

Findings

It is found that defects increase temperature of material surface. Besides, the materials with little defects have a smaller COF than base materials, as the large block defects make the COF larger than base materials.

Originality/value

Except for effects of defects were simulated in model, how to initialize the surface temperature status that many reports do not take into account can be preferred. And the model is convenient to simulate complex composite materials by setting different properties of cells.

Details

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

Keywords

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…

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

1 – 10 of 651