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Article
Publication date: 8 April 2014

Jun Sun, Xinlong Zhu, Liang Zhang, Xianyi Wang, Chunmei Wang, Hu Wang and Xiaoyong Zhao

Current lubrication analyses of misaligned journal bearings were generally performed under some given preconditions. To make the lubrication analysis closer to the actual…

Abstract

Purpose

Current lubrication analyses of misaligned journal bearings were generally performed under some given preconditions. To make the lubrication analysis closer to the actual situation and usable to the journal bearing design, the purpose of this paper was to calculate the lubrication characteristics of misaligned journal bearings considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time.

Design/methodology/approach

The lubrication of bearings was analyzed using the average Reynolds equation. The deformation of the bearing surface under oil film pressure was calculated by a compliance matrix method. The compliance matrix was established by finite element analysis of the bearing housing. The viscosity-pressure and viscosity–temperature equations were used in the analysis.

Findings

The oil viscosity-pressure relationship has a significant effect on the lubrication of misaligned journal bearings. The surface roughness will affect the lubrication of misaligned journal bearings when the eccentricity ratio and angle of journal misalignment are all large. The directional parameter of the surface has an obvious effect on the lubrication of misaligned journal bearings. The deformation of the bearing surface has a remarkable effect on the lubrication of misaligned journal bearings.

Originality/value

The lubrication characteristics of misaligned journal bearings were calculated considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time. The results of this paper are helpful to the design of the bearing.

Details

Industrial Lubrication and Tribology, vol. 66 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 13 November 2017

Rahul Kumar, Mohammad Sikandar Azam, Subrata Kumar Ghosh and Hasim Khan

The aim of this paper is to study the effect of deterministic roughness and small elastic deformation of surface on flow rates, load capacity and coefficient of friction…

Abstract

Purpose

The aim of this paper is to study the effect of deterministic roughness and small elastic deformation of surface on flow rates, load capacity and coefficient of friction in Rayleigh step bearing under thin film lubrication.

Design/methodology/approach

Reynolds equation, pressure-density relationship, pressure-viscosity relationship and film thickness equation are discretized using finite difference method. Progressive mesh densification (PMD) method is applied to solve the related equations iteratively.

Findings

The nature and shape of roughness play a significant role in pressure generation. It has been observed that square roughness dominates the pressure generation for all values of minimum film thickness. Deformation more than 100 nm in bounding surfaces influences the film formation and pressure distribution greatly. Divergent shapes of film thickness in step zone causes a delay of pressure growth and reduces the load capacity with decreasing film thickness. The optimum value of film thickness ratio and step ratios have been found out for the maximum load capacity and minimum coefficient of friction, which are notably influenced by elastic deformation of the surface.

Practical implications

It is expected that these findings will help in analysing the performance parameters of a Rayleigh step bearing under thin film lubrication more accurately. It will also help the designers, researchers and manufacturers of bearings.

Originality/value

Most of the previous studies have been limited to sinusoidal roughness and thick film lubrication in Rayleigh step bearing. Effect of small surface deformation due to generated pressure in thin film lubrication is significant, as it influences the performance parameters of the bearing. Different wave forms such as triangular, sawtooth, sinusoidal and square formed during finishing operations behaves differently in pressure generation. The analysis of combined effect of roughness and small surface deformation has been performed under thin film lubrication for Rayleigh step bearing using PMD as improved methods for direct iterative approach.

Details

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

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Article
Publication date: 15 August 2008

Mumin Sahin

The purpose of this paper is to examine the effects of the welding deformation and surface roughness in cold pressure welding on the tensile strength and the fatigue…

Abstract

Purpose

The purpose of this paper is to examine the effects of the welding deformation and surface roughness in cold pressure welding on the tensile strength and the fatigue strength of joined sheets. Additionally, the paper seeks to analyse the hardness variations and microstructures at the welding interface.

Design/methodology/approach

Cold pressure welding is a method of joining similar or dissimilar ductile metals. It can be applied by bringing into close contact the surfaces of virgin metal specimens that appear due to the breakdown of the surface layers caused by bulk plastic deformation. Cold pressure welding is applied to test parts without too long a delay after the preparation of surfaces. The application of welding in 10 min affects importantly the weld strength. As this time is increased, the weld strength of the joints is decreased. The determination of deformation amount is found by determination of the reduction (R) at the total thickness of the two parts after the welding process.

Findings

The weld strength increases as the surface roughness and weld deformation of the joined sheets increase. The length of bond zones increases with increasing deformation. Therefore, the weld strength of parts depends on the length of bond zones. Then, there is an effect of surface roughness on the welding strength. Joined sheets show resistance to little fluctuating tensile stress. It is observed that the parts rupture from the welding‐interface hardness values are about the same at interfaces of sheets having different surface roughness and equal deformation (60 per cent). But, if it is considered that hardness of aluminium material purchased is about 53 HV, it can be said that the hardness increases in joined parts because of local hardening during deformation in cold pressure welding method as lap welding. Bond formation at interfaces of joined sheets having Ra=5 μm surface roughness and deformation ratio 60 per cent is shown to be successful in the microstructure photo.

Research limitations/implications

Surface roughness and deformation values can be increased in further studies.

Originality/value

The paper offers insight into the effects of surface roughness on weldability.

Details

Industrial Lubrication and Tribology, vol. 60 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 March 2013

Xiaoyong Zhao, Jun Sun, Chunmei Wang, Hu Wang and Mei Deng

Current lubrication analyses of misaligned journal bearings are generally performed under some given preconditions. The purpose of this paper is to calculate the…

Abstract

Purpose

Current lubrication analyses of misaligned journal bearings are generally performed under some given preconditions. The purpose of this paper is to calculate the lubrication characteristics of a journal bearing with journal misalignment caused by shaft deformation under load, considering the surface roughness, thermal effect and (thermal and elastic) deformation of bearing surface simultaneously.

Design/methodology/approach

The lubrication of bearing was analyzed by average flow model based generalized Reynolds equation. The deformation of bearing surface under pressure or heat of oil film was calculated by compliance matrix method. The compliance matrix was established by finite element analysis. The temperature distributions of oil film and bearing were calculated by energy equation and heat conduction equation.

Findings

When the thermal deformation of bearing and journal surface is considered, the radius clearance affects not only the value of the maximum oil film pressure and minimum oil film thickness, but also the distribution of oil film pressure and thickness of misaligned bearing. The effect of thermal deformation of bearing on the performance of misaligned bearing is larger than that of elastic deformation of bearing. Whether or not the surface roughness affects the performance of misaligned bearing and the affecting level depends greatly on the condition of deformation of bearing surface.

Originality/value

The surface roughness, thermal effect and (thermal and elastic) deformation of bearing surface were considered simultaneously in the thermoelastohydrodynamic lubrication analysis of bearing with journal misalignment caused by shaft deformation under load. The results of this paper are helpful to the design of the bearing.

Details

Industrial Lubrication and Tribology, vol. 65 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 4 October 2019

Binbin Su, Wei Huang and Xiaolei Wang

This paper aims to experimentally investigate the elastic deformation behavior of surface texture in soft contacts under lubricated condition.

Abstract

Purpose

This paper aims to experimentally investigate the elastic deformation behavior of surface texture in soft contacts under lubricated condition.

Design/methodology/approach

Dimples with two typical distribution patterns are fabricated on the contacting surface by Quasi-LIGA technique. In situ observation on the elastic deformation of contacting surface is performed through optical interferometry. Comparisons of the elastic deformation around the dimples in different distribution patterns are conducted.

Findings

The results show that the effect of dimple distribution patterns on elastic deformation becomes increasingly serious with the growth of applied load. Dimples in square distribution present a stronger interaction with each other and lead to a more alleviative deformation under heavier load condition. The action range of dimple, especially in square distribution, is seriously compressed by surrounding dimples.

Originality/value

Square distribution is preferentially suggested for surface texture with respect to minimum elastic deformation in soft contacts under elastohydrodynamic lubrication condition.

Details

Industrial Lubrication and Tribology, vol. 71 no. 10
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 February 2012

Jun Sun, Xiaoxia Cai and Liping Liu

The elastic deformation of crankshaft bearing surface will be caused when acted by oil film pressure, which will affect the lubrication performance of crankshaft bearing…

Abstract

Purpose

The elastic deformation of crankshaft bearing surface will be caused when acted by oil film pressure, which will affect the lubrication performance of crankshaft bearing. The model of the single bearing housing was usually used in the calculation of the elastic deformation of bearing surface. In actual internal combustion engine, the main bearing housing is combined together with engine block; deformation of the main bearing surface will be affected by deformation of the engine block. The purpose of this paper is to investigate the effect of deformation of the whole engine block on the hydrodynamic lubrication performance of main bearings.

Design/methodology/approach

The loads of main bearings were calculated by the whole crankshaft beam‐element finite element method. The lubrication of crankshaft bearings was analyzed by dynamic method. The elastic deformations of bearing surface under oil film pressure were calculated by compliance matrix method. The compliance matrix was established by finite element analysis.

Findings

It may be not necessary to consider the effect of elastic deformation of bearing surface under film pressure in the lubrication analyses of main bearings for internal combustion engine when the very high calculating accuracy is not required.

Originality/value

The elastohydrodynamic lubrications of crankshaft bearings considering the deformation of engine block were analyzed for the main bearings of an engine. Till now, whether or not the complicated model of the whole cylinder block should be considered to calculate the elastic deformation of main bearing surface in the lubrication analyses of crankshaft main bearings has not been done.

Details

Industrial Lubrication and Tribology, vol. 64 no. 1
Type: Research Article
ISSN: 0036-8792

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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…

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

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Article
Publication date: 12 March 2018

Yuqin Wen and Jin Yuan Tang

This paper aims to study the contact between rough cylindrical surfaces considering the elastic-plastic deformation of asperities.

Abstract

Purpose

This paper aims to study the contact between rough cylindrical surfaces considering the elastic-plastic deformation of asperities.

Design/methodology/approach

The elastic deformation of the nominal surface of the curved surface is considered, the contact area is discretized by the calculus thought and then the nominal distance between two surfaces is obtained by iteration after the pressure distribution is assumed. On the basis of the Zhao, Maietta and Chang elastic-plastic model, the contact area and the contact pressure of the rough cylindrical surfaces are calculated by the integral method, and then the solution for the contact between rough cylindrical surfaces is obtained.

Findings

The contact characteristic parameters of smooth surface Hertz contact, elastic contact and elastic-plastic contact between rough cylindrical surfaces are calculated under different plastic indexes and loads, and the calculation results are compared and analyzed. The analysis shows that the solution considering the elastic-plastic deformation of asperities for the contact between rough cylindrical surfaces is scientific and rational.

Originality/value

This paper provides a new effective method for the calculation of the contact between rough cylindrical surfaces.

Details

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

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Article
Publication date: 17 October 2018

Xiaokai Mu, Qingchao Sun, Wei Sun, Yunlong Wang, Chuanhua Wang and Xiaobang Wang

The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper…

Abstract

Purpose

The traditional precision design only takes the influence of geometric tolerance of the parts and does not involve the load deformation in the assembly process. This paper aims to analyze the influence mechanism of flexible parts deformation on the geometric precision, and then to ensure the reliability and stability of the mechanical system.

Design/methodology/approach

Firstly, this paper adopts the N-GPS to analyze the influence mechanism of flexible parts deformation on the geometric precision and constructs a coupling 3D tolerance mathematical model of the geometric tolerance and the load deformation deviation based on the SDT theory, homogeneous coordinate transformation theory and surface authentication idea. Secondly, the least square method is used to fit the deformation surface of the mating surface under load so as to complete the conversion from the non-ideal element to the ideal element.

Findings

This paper takes the horizontal machining center as a case to obtain the deformation information of the mating surface under the self-weight load. The results show that the deformation deviation of the parts has the trend of transmission and accumulation under the load. The terminal deformation cumulative amount of the system is up to –0.0249 mm, which indicated that the influence of parts deformation on the mechanical system precision cannot be ignored.

Originality/value

This paper establishes a comprehensive 3D tolerance mathematical model, which comprehensively considers the effect of the dimensional tolerance, geometric tolerance and load deformation deviation. By this way, the assembly precision of mechanical system can be accurately predicted.

Details

Engineering Computations, vol. 35 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 August 1996

Jacqueline R. Postle and Ron Postle

Aims to analyse unique deformation properties of textile materials in terms of basic mechanical properties. Models fabric deformation as a nonlinear dynamical system so…

Abstract

Aims to analyse unique deformation properties of textile materials in terms of basic mechanical properties. Models fabric deformation as a nonlinear dynamical system so that a fabric can be completely specified in terms of its mechanical behaviour under general boundary conditions. Fabric deformation is dynamically analogous to waves travelling in a fluid. A localized two‐dimensional deformation evolves through the fabric to form a three‐dimensional drape or fold configuration. The nonlinear differential equations arising in the analysis of fabric deformation belong to the Klein‐Gordon family of equations which becomes the sine‐Gordon equation in three dimensions. The sine‐Gordon equation has its origins in the study of Bäcklund Transformations in differential geometry. Describes fabric deformation as a series of transformations of surfaces, defined in terms of curvature parameters using Gaussian representation of surfaces. By considering a deformed fabric as a two‐dimensional surface, algebraically constructs analytical solutions of fabric deformation by solving the sine‐Gordon Equation. The theory of Bäcklund Transformations is used to transform a trivial solution into a series of solitary wave solutions. These analytical expressions describing the curvature parameters of a surface represent actual solutions of fabric dynamical systems.

Details

International Journal of Clothing Science and Technology, vol. 8 no. 3
Type: Research Article
ISSN: 0955-6222

Keywords

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