A solution considering elastic-plastic deformation of asperities for contact between rough cylindrical surfaces

2018 ◽  
Vol 70 (2) ◽  
pp. 353-362 ◽  
Author(s):  
Yuqin Wen ◽  
Jin Yuan Tang
Keyword(s):  
Plastic Deformation ◽  
Contact Area ◽  
Design Methodology ◽  
Hertz Contact ◽  
Characteristic Parameters ◽  
Content Type ◽  
Elastic Plastic ◽  
Calculation Results ◽  
Contact Characteristic ◽  
Nominal Surface

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.

Virtual Material Model of Joint Interfaces Considering Elastic-Plastic Deformation of Asperities

2013 ◽  
Vol 457-458 ◽  
pp. 257-261
Author(s):  
Li Gang Cai ◽  
Teng Yun Xu ◽  
Yong Sheng Zhao
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Fractal Theory ◽  
Material Model ◽  
Contact Theory ◽  
Hertz Contact ◽  
Calculation Methods ◽  
Elastic Plastic ◽  
Element Simulation ◽  
Simulation Results

A virtual material model of joint interfaces was established based on the Hertz contact theory and fractal theory, this model was improved by considering the influence of the elastic-plastic deformation of asperities and ameliorating the calculation methods of the elastic modulus. The simulation results of elastic-plastic considered and elastic-plastic unconsidered were compared, moreover, the finite element simulation results and experimental results were compared to fully explain the necessity of considering the influence of the elastic-plastic deformation and the the correctness of the method to calculate the elastic modulus. The research suggested that under a same load the elastic modulus of the model considering the influence of the elastic-plastic deformation was slightly larger than the un considering one, which means it could describe the characteristics of joint interfaces more accurately.

Friction analysis of anisotropic surface for viscoelastic material

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yang Zhao ◽  
Heng Liu ◽  
Nanshan Wang ◽  
Bowen Fan ◽  
Meng Li
Keyword(s):  
Elastic Modulus ◽  
Contact Area ◽  
Design Methodology ◽  
Sliding Friction ◽  
Vertical Direction ◽  
Content Type ◽  
Partial Contact ◽  
Anisotropic Surface ◽  
The Coefficient Of Friction ◽  
Friction Analysis

Purpose The anisotropic surfaces of viscoelastic materials play a role in sliding friction; the purpose of this paper is to study the effect of the anisotropic surfaces on contact area and the friction coefficient. Design/methodology/approach A complex elastic modulus and an anisotropic power spectrum are used to compute the coefficient of friction based on the extension Persson theory which considers the partial contact and the variation in the roughness slopes. Findings The ratios of the relative contact area that varies with velocity are obtained with different angles and eccentricities, and the effect of the elastic modulus needs to be considered. The coefficients of the friction parallel to the direction of motion decrease as the angle increases, or as the eccentricity decreases. The friction coefficients in the vertical direction change irregularly when the angles or eccentricities increase. Originality/value An extension of Persson’s work considering the partial contact and the effective mean square slope of the roughness is applied to study sliding friction, and the effect of the elastic modulus on contact area is considered.

Contact mechanics of elastic-plastic fractal surfaces and static friction analysis of asperity scale

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wujiu Pan ◽  
Xiaopeng Li ◽  
Xue Wang
Keyword(s):  
Plastic Deformation ◽  
Fractal Dimension ◽  
Friction Coefficient ◽  
Contact Mechanics ◽  
Normal Load ◽  
Boundary Value ◽  
Static Friction ◽  
Content Type ◽  
Elastic Plastic ◽  
Static Friction Coefficient

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.

An Elliptical Elastic-Plastic Microcontact Model Developed for an Ellipsoid in Contact With a Smooth Rigid Flat

2007 ◽  
Vol 129 (4) ◽  
pp. 772-782 ◽  
Author(s):  
Li Po Lin ◽  
Jen Fin Lin
Keyword(s):  
Plastic Deformation ◽  
Contact Pressure ◽  
Contact Area ◽  
Elastoplastic Deformation ◽  
Major Axis ◽  
Contact Load ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Deformation Regime ◽  
Von Mises

The determination of the elastoplastic deformation regime arising at the microcontact of a deformable ellipsoid and a rigid smooth flat was the main purpose of this study. One-eighth of an ellipsoid and a flat plate were taken as the contact bodies in the finite element analysis, and a mesh scheme of multisize elements was applied. Two observed phenomena regarding the contact pressures and the equivalent von Mises stresses formed at the contact area are given in order to identify the inception of the fully plastic deformation regime of an ellipsoid with an ellipticity ke. If the ellipticity (k) of an elliptical contact area is defined as the length ratio of the minor axis to the major axis, it is asymptotic to the ke value when the interference is sufficiently increased, irrespective of the ke value. The dimensionless interference regime associated with the elastoplastic deformation regime is narrowed by increasing the ellipticity of the ellipsoid (ke). Significant differences in the microcontact parameters such as the contact pressure, the contact area, and the contact load were found to be a function of the interference and the ke parameter of an ellipsoid. The interferences corresponding to the inceptions of the elastoplastic and fully plastic deformation regimes are both increased if the ke value is lowered. The interference, the contact area, and the contact load predicted by the present model for the behavior demonstrated at the inception of the elastoplastic deformation regime are lower than those obtained from the Horng model (Horng, J. H., 1998, “An Elliptical Elastic-Plastic Asperity Microcontact Model for Rough Surfaces,” ASME J. Tribol., 120, pp. 82–88) and the Jeng-Wang model (Jeng, Y. R., and Wang, P. Y., 2003, “An Elliptical Microcontact Model Considering Elastic, Elastoplastic, and Plastic Deformation,” ASME J. Tribol., 125, pp. 232–240). Big differences in the results of the average contact pressure, the contact area, and the contact load among the above microcontact models are discussed. The discrepancies are also explained from the developments of these models and boundary conditions set for the elastoplastic deformation regime.

Elastic-Plastic Contact Analysis of a Deformable Sphere and a Rigid Flat with Friction Effect

2013 ◽  
Vol 644 ◽  
pp. 151-156 ◽  
Author(s):  
Li Wang ◽  
Yang Xiang
Keyword(s):  
Plastic Deformation ◽  
Contact Area ◽  
Contact Load ◽  
Deformation Analysis ◽  
Elastic Plastic ◽  
Friction Effect ◽  
Finite Element Software ◽  
Plastic Deformation Process ◽  
Rigid Plane ◽  
The Impact

Elastic-plastic deformation analysis of the deformable sphere and the rigid plane was studied using the finite element software,this paper was focused on the impact of the friction effects on the deformation of the elastic-plastic deformation under considering the material strain stiffening properties,studies have shown that，the strain stiffening feature increases the contact load while reducing the contact area，the friction effect reduce both the contact load and contact area during elastic-plastic deformation process of the deformable sphere with increasing contact interference.

scholarly journals Vulnerable adults in police custody

2019 ◽  
Vol 22 (1) ◽  
pp. 5-8
Author(s):  
Ian Cummins
Keyword(s):  
Design Methodology ◽  
Research Literature ◽  
Police Custody ◽  
England And Wales ◽  
Content Type ◽  
Increased Risk ◽  
Vulnerable Adults

Purpose The purpose of this paper is to discuss the recent National Appropriate Adult Network (NAAN) report on the role of the appropriate adult. Design/methodology/approach This paper is based on the NAAN report and a review of relevant policy and research literature. Findings There to Help 2 highlights that there are still significant gaps in the provision of appropriate adult schemes across England and Wales. These gaps potentially place vulnerable adults at increased risk. Originality/value This paper is a review of recent research.

Co-workers’ perceptions of and reactions to employee’s involuntary demotion

2019 ◽  
Vol 41 (4) ◽  
pp. 740-757 ◽  
Author(s):  
Sophie Hennekam ◽  
Subramaniam Ananthram ◽  
Steve McKenna
Keyword(s):  
Design Methodology ◽  
Emotional Responses ◽  
Emotional Reaction ◽  
Content Type ◽  
Informational Justice ◽  
Behavioural Responses ◽  
Behavioural Reaction ◽  
Three Stages ◽  
Depth Interviews ◽  
The Way

Purpose The purpose of this paper is to investigate how individuals perceive and react to the involuntary demotion of a co-worker in their organisation. Design/methodology/approach The authors draw on 46 semi-structured in-depth interviews (23 dyads) with co-workers of demoted individuals. Findings The findings suggest that an individual’s observation of the demotion of a co-worker has three stages: their perception of fairness, their emotional reaction and their behavioural reaction. The perception of fairness concerned issues of distributive, procedural, interpersonal and informational justice. The emotional responses identified were feelings of disappointment/disillusion, uncertainty, vulnerability and anger. Finally, the behavioural reactions triggered by their emotional responses included expressions of voice, loyalty, exit and adaptation. Originality/value Perceptions of (in)justice perpetrated on others stimulate emotional and behavioural responses, which impacts organisational functioning. Managers should therefore pay attention to the way a demotion is perceived, not only by those directly concerned, but also by co-workers as observers.

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