Multiple Inhomogeneous Inclusions and Cracks in a Half Space Under Elastohydrodynamic Lubrication Contact

2015 ◽  
Vol 07 (01) ◽  
pp. 1550003 ◽  
Author(s):  
Qingbing Dong ◽  
Kun Zhou
Keyword(s):  
Half Space ◽  
Analytic Solution ◽  
Fluid Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Governing Equations ◽  
Equivalent Inclusion Method ◽  
Surface Displacements ◽  
Equivalent Inclusion ◽  
Lubricated Contact ◽  
Modified Conjugate Gradient Method

A semi-analytic solution is presented for multiple inhomogeneous inclusions and cracks in a half-space under elastohydrodynamic lubrication contact. In formulating the governing equations, each inhomogeneous inclusion embedded under the contacting surfaces is modeled as a homogeneous inclusion with initial eigenstrains plus unknown equivalent eigenstrains by employing Eshelby's equivalent inclusion method, while each crack of mixed modes I and II is treated as a distribution of climb and glide dislocations with unknown densities according to the dislocation distribution technique. Such a treatment converts the problem into a homogeneous lubricated contact with disturbed deformation due to the inclusions and cracks. The unknowns in the governing equations are integrated by a numerical algorithm and determined iteratively by utilizing a modified conjugate gradient method. The iterative process is performed until the convergence of the half-space surface displacements, which involve the displacements due to the inhomogeneous inclusions and cracks as well as the fluid pressure. Samples are presented to demonstrate the generality of the solution.

Elastohydrodynamic Lubrication of Inhomogeneous Materials Using the Equivalent Inclusion Method

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Zhanjiang Wang ◽  
Dong Zhu ◽  
Qian Wang
Keyword(s):  
Film Thickness ◽  
Surface Deformation ◽  
Fluid Pressure ◽  
Surface Displacement ◽  
Elastohydrodynamic Lubrication ◽  
Functionally Graded ◽  
Inhomogeneous Materials ◽  
Equivalent Inclusion Method ◽  
Inclusion Method ◽  
Equivalent Inclusion

Solid materials forming the boundaries of a lubrication interface may be elastoplastic, heat treated, coated with multilayers, or functionally graded. They may also be composites reinforced by particles or have impurities and defects. Presented in this paper is a model for elastohydrodynamic lubrication interfaces formed with these realistic materials. This model considers the surface deformation and subsurface stresses influenced by material inhomogeneities, where the inhomogeneities are replaced by inclusions with properly determined eigenstrains by means of the equivalent inclusion method. The surface displacement or deformation caused by inhomogeneities is introduced to the film thickness equation. The stresses are the sum of those caused by the fluid pressure and the eigenstrains. The lubrication of a material with a single inhomogeneity, multiple inhomogeneities, and functionally graded coatings are analyzed to reveal the influence of inhomogeneities on film thickness, pressure distribution, and subsurface stresses.

scholarly journals Analysis of Line Contact Elastohydrodynamic Lubrication with the Particles under Rough Contact Surface

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Keying Chen ◽  
Liangcai Zeng ◽  
Juan Chen ◽  
Xianzhong Ding
Keyword(s):  
Film Thickness ◽  
Rough Surface ◽  
Thickness Distribution ◽  
Traction Force ◽  
Elastohydrodynamic Lubrication ◽  
Equation System ◽  
Line Contact ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
The Matrix

A numerical solution for line contact elastohydrodynamic lubrication (EHL) occurring on the rough surface of heterogeneous materials with a group of particles is presented in this study. The film thickness disturbance caused by particles and roughness is considered into the solution system, and the film pressure between the contact gap generated by the particles and the surface roughness is obtained through a unified Reynold equation system. The inclusions buried in the matrix are made equivalent to areas with the same material as that of the matrix through Eshelby’s equivalent inclusion method and the roughness is characterized by related functions. The results present the effects of different rough topographies combined with the related parameters of the particles on the EHL performance, and the minimum film thickness distribution under different loads, running speeds, and initial viscosities are also investigated. The results show that the roughness morphology and the particles can affect the behavior of the EHL, the traction force on a square rough surface is smaller, and the soft particles have more advantages for improving the EHL performance.

Semi-Analytic Solution of Multiple Inhomogeneous Inclusions and Cracks in an Infinite Space

2015 ◽  
Vol 12 (01) ◽  
pp. 1550002 ◽  
Author(s):  
Kun Zhou ◽  
Rongbing Wei ◽  
Guijun Bi ◽  
Xu Wang ◽  
Bin Song ◽  
...  
Keyword(s):  
Analytic Solution ◽  
The Finite Element Method ◽  
Infinite Space ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Dislocation Densities ◽  
Distributed Dislocation ◽  
Potential Applications ◽  
Novel Method ◽  
Dislocation Technique

This work develops a semi-analytic solution for multiple inhomogeneous inclusions of arbitrary shape and cracks in an isotropic infinite space. The solution is capable of fully taking into account the interactions among any number of inhomogeneous inclusions and cracks which no reported analytic or semi-analytic solution can handle. In the solution development, a novel method combining the equivalent inclusion method (EIM) and the distributed dislocation technique (DDT) is proposed. Each inhomogeneous inclusion is modeled as a homogenous inclusion with initial eigenstrain plus unknown equivalent eigenstrain using the EIM, and each crack of mixed modes I and II is modeled as a distribution of edge climb and glide dislocations with unknown densities. All the unknown equivalent eigenstrains and dislocation densities are solved simultaneously by means of iteration using the conjugate gradient method (CGM). The fast Fourier transform algorithm is also employed to greatly improve computational efficiency. The solution is verified by the finite element method (FEM) and its capability and generality are demonstrated through the study of a few sample cases. This work has potential applications in reliability analysis of heterogeneous materials.

A Three-Dimensional Model of Line-Contact Elastohydrodynamic Lubrication for Heterogeneous Materials with Inclusions

2016 ◽  
Vol 08 (02) ◽  
pp. 1650014 ◽  
Author(s):  
Kun Zhou ◽  
Qingbing Dong
Keyword(s):  
Film Thickness ◽  
Half Space ◽  
Surface Deformation ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Line Contact ◽  
Lubricant Film Thickness ◽  
Equivalent Inclusion Method ◽  
Surface Contact

This paper develops a three-dimensional (3D) model for a heterogeneous half-space with inclusions distributed periodically beneath its surface subject to elastohydrodynamic lubrication (EHL) line-contact applied by a cylindrical loading body. The model takes into account the interactions between the loading body, the fluid lubricant and the heterogeneous half-space. In the absence of subsurface inclusions, the surface contact pressure distribution, the half-space surface deformation and the lubricant film thickness profile are obtained through solving a unified Reynolds equation system. The inclusions are homogenized according to Eshelby’s equivalent inclusion method (EIM) with unknown eigenstrains to be determined. The disturbed half-space surface deformations induced by the subsurface inclusions or eigenstrains are iteratively introduced into the lubricant film thickness until the surface deformation finally converges. Both time-independent smooth surface contact and time-dependent rough surface contact are considered for the lubricated contact problem.

Novel Model for Partial-Slip Contact Involving a Material With Inhomogeneity

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Zhanjiang Wang ◽  
Xiaoqing Jin ◽  
Leon M. Keer ◽  
Qian Wang
Keyword(s):  
Half Space ◽  
Three Dimensional ◽  
Elastic Half Space ◽  
Partial Slip ◽  
Fast Method ◽  
Contact Center ◽  
Displacement Fields ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Parametric Studies

Contacts involving partial slip are commonly found at the interfaces formed by mechanical components. However, most theoretical investigations of partial slip are limited to homogeneous materials. This work proposes a novel and fast method for partial-slip contact involving a material with an inhomogeneity based on the equivalent inclusion method, where the inhomogeneity is replaced by an inclusion with properly chosen eigenstrains. The stress and displacement fields due to eigenstrains are formulated based on the half-space inclusion solutions recently derived by the authors and solved with a three-dimensional fast Fourier transform algorithm. The effectiveness and accuracy of the proposed method is demonstrated by comparing its solutions with those from the finite element method. The partial slip contact between an elastic ball and an elastic half space containing a cuboidal inhomogeneity is further investigated. A number of in-depth parametric studies are performed for the cuboidal inhomogeneity with different sizes and at different locations. The results reveal that the contact behavior of the inhomogeneous material is more strongly influenced by the inhomogeneity when it is closer to the contact center and when its size is larger.

Elastohydrodynamic Lubrication Analysis of Point Contacts With Consideration of Material Inhomogeneity

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Zhang Shengguang ◽  
Wang Wenzhong ◽  
Zhao Ziqiang
Keyword(s):  
Film Thickness ◽  
Numerical Algorithms ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Bearing ◽  
Inclusion Problem ◽  
Material Inhomogeneity ◽  
Equivalent Inclusion Method ◽  
Lubrication Performance ◽  
The Matrix ◽  
Lubricated Contact

Inhomogeneities in matrix may significantly affect the performance of mechanical elements, such as possible fatigue life reduction for rolling bearing due to stress concentration induced by inhomogeneities; on the other hand, most components operate under lubrication environment. So far the numerical algorithms to solve lubrication problems without the consideration of inhomogeneities or inclusions are well developed. In this paper, the combination of elastohydrodynamic lubrication (EHL) and inclusion problem is realized to consider the effect of material inhomogeneity on the lubrication performance and subsurface stress distribution, etc. The matrix inhomogeneity will induce disturbed displacement, which will modify the film thickness and consequently result in the change of lubricated contact pressure distribution, etc. The matrix inhomogeneity is treated as the homogeneous inclusion with equivalent eigenstrain according to equivalent inclusion method (EIM), and the disturbed displacement is calculated by semi-analytical method (SAM). While the pressure and film thickness distributions are obtained by solving Reynolds equation. The iterative process is realized to consider the interaction between lubrication behavior and material response. The results show the inhomogeneity in contacting body will greatly influence the lubricated contact performance. The influences are different between compliant and stiff inhomogeneity. It is also found that different sizes and positions of inhomogeneity can significantly affect the contact characteristic parameters.

An Efficient Numerical Model of Elastohydrodynamic Lubrication for Transversely Isotropic Materials

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Zhanjiang Wang ◽  
Yinxian Zhang
Keyword(s):  
Film Thickness ◽  
Half Space ◽  
Fluid Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Transversely Isotropic ◽  
Vertical Displacement ◽  
Constant Load ◽  
Von Mises Stress ◽  
Isotropic Materials ◽  
Transversely Isotropic Materials

An elastohydrodynamic lubrication model for a rigid ball in contact with a transversely isotropic half-space is constructed. Reynolds equation, film thickness equation, and load balance equation are solved using the finite difference method, where the surface vertical displacement or deformation of transversely isotropic half-space is considered through the film thickness equation. The numerical methods are verified by comparing the displacements and stresses with those from Hertzian analytical solutions. Furthermore, the effects of elastic moduli, entertainment velocities, and lubricants on fluid pressure, film thickness, and von Mises stress are analyzed and discussed under a constant load. Finally, the modified Hamrock–Dowson equations for transversely isotropic materials to calculate central film thickness and minimum film thickness are proposed and validated.

Numerical Modeling of Partial Slip Contact Involving Inhomogeneous Materials

2012 ◽  
Author(s):  
Zhanjiang Wang ◽  
Xiaoqing Jin ◽  
Leon M. Keer ◽  
Qian Wang
Keyword(s):  
Half Space ◽  
Three Dimensional ◽  
Elastic Half Space ◽  
Partial Slip ◽  
Inhomogeneous Materials ◽  
Displacement Fields ◽  
Homogeneous Solutions ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Stress And Displacement Fields

When solving the problems involving inhomogeneous materials, the influence of the inhomogeneity upon contact behavior should be properly considered. This research proposes a fast and novel method, based on the equivalent inclusion method where inhomogeneity is replaced by an inclusion with properly chosen eigenstrains, to simulate contact partial slip of the interface involving inhomogeneous materials. The total stress and displacement fields represent the superposition of homogeneous solutions and perturbed solutions due to the chosen eigenstrains. In the present numerical simulation, the half space is meshed into a number of cuboids of the same size, where each cuboid is has a uniform eigenstrain. The stress and displacement fields due to eigenstrains are formulated by employing the recent half-space inclusion solutions derived by the authors and solved using a three-dimensional fast Fourier transform algorithm. The partial slip contact between an elastic ball and an elastic half space containing a cuboidal inhomogeneity was investigated.

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