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 Microcontact Analysis of a Sphere and a Flat Plate

2007 ◽  
Vol 23 (4) ◽  
pp. 341-352 ◽  
Author(s):  
J. L. Liou ◽  
J. F. Lin
Keyword(s):  
Surface Roughness ◽  
Flat Plate ◽  
Contact Pressure ◽  
Contact Area ◽  
Normal Load ◽  
Contact Load ◽  
Asperity Contact ◽  
Elastic Plastic ◽  
Deformation Regime ◽  
Maximum Contact

ABSTRACTThe elastic-plastic microcontact model of a sphere in contact with a flat plate is developed in the present study to investigate the effect of surface roughness on the total contact area and contact load. From the study done by the finite element method, the dimensionless asperity contact area, average contact pressure, and contact load in the elastoplastic regime are assumed to be a power form as a function of dimensionless interference (δ/δec). The coefficients and exponents of the power form expressions can be determined by the boundary conditions set at the two ends of the elastoplastic deformation regime. The contact pressures evaluated by the present model are compared with those predicted by the Hertz theory, without considering the surface roughness and the reported model, including the roughness effect, but only manipulating in the elastic regime. The area of non-zero contact pressure is enlarged if the surface roughness is considered in the microcontact behavior. The maximum contact pressure is lowered by the presence of surface roughness if the contact load is fixed. Under a normal load, both the contact pressure and the contact area are elevated by raising the plasticity index for the surface of the same surface roughness.

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.

Finite Element Analysis of Contact and Structural Phenomena of a Lab-Scale Electromagnetic Accelerator

2007 ◽  
Author(s):  
Bummo Chung ◽  
Itzhak Green ◽  
Richard S. Cowan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Pressure ◽  
Contact Area ◽  
Von Mises Stress ◽  
Mode Shapes ◽  
Element Analysis ◽  
Vibrational Characteristics ◽  
Von Mises ◽  
Electromagnetic Accelerator

This work presents a finite element analysis (FEA) of the initial armature-to-rail contact of a lab-scale electromagnetic accelerator (12.5 mm rail height) and a modal analysis of the armature. Structural results of the von Mises stress, the contact pressure, and the contact area are presented with the vibrational characteristics (frequencies and mode shapes) of the un-stressed and the pre-stressed armature.

Spherical Elastic–Plastic Contact Model for Power-Law Hardening Materials Under Combined Normal and Tangential Loads

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Bin Zhao ◽  
Song Zhang ◽  
Leon M. Keer
Keyword(s):  
Contact Pressure ◽  
Power Law ◽  
Contact Area ◽  
Normal Force ◽  
Tangential Force ◽  
Tangential Displacement ◽  
Tangential Load ◽  
Elastic Plastic ◽  
Normal And Tangential Loads ◽  
Von Mises

The contact between a power-law hardening elastic–plastic sphere and a rigid flat under combined normal and tangential loads in full stick is studied in this work. The displacement-driven loading is used since the frictional contact problems under the displacement-driven loading are widespread in the fields of metal forming and orthogonal cutting. The loading process is as follows: First, a normal displacement-driven loading is imposed on the rigid flat and kept constant; then, an additional tangential displacement-driven loading is applied to the rigid flat. The elastic–plastic contact behavior in presliding is investigated with a proposed finite element (FE) model, including the tangential force, the von Mises stress, the normal force, the contact pressure, and the contact area. The effect of the strain-hardening exponent on contact behavior is considered. It is seen that the tangential force increases nonlinearly with the increase of the tangential displacement, exhibiting gradual stiffness reduction which implies that the junction becomes more plastic. The von Mises stresses moves along the direction of the tangential load, while the maximum stress moves to the contact surface from the below. The normal force diminishes as the tangential load increases, and more obviously for the lower hardening exponent cases. The contact pressure also decreases more significantly for the lower hardening exponent cases. In addition, smaller exponents result in a greater increase of the contact area. The empirical expressions of the tangential force and the contact area in the tangential loading process are also proposed by fitting to the FE results.

Experimental and Theoretical Study of the Contact Mechanics of Five Total Knee Joint Replacements

1995 ◽  
Vol 209 (4) ◽  
pp. 225-231 ◽  
Author(s):  
T Stewart ◽  
Z M Jin ◽  
D Shaw ◽  
D D Auger ◽  
M Stone ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Knee Joint ◽  
Contact Pressure ◽  
Contact Stress ◽  
Linear Elasticity ◽  
Contact Area ◽  
Elasticity Analysis ◽  
Joint Replacements ◽  
Total Knee ◽  
Maximum Contact

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component particularly at flexion angles near 90°. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

scholarly journals Elasto-plastic analysis of the contact region between a rigid ellipsoid and a semi-flat surface

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879739 ◽  
Author(s):  
Pengyang Li ◽  
Lingxia Zhou ◽  
Fangyuan Cui ◽  
Quandai Wang ◽  
Meiling Guo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Plastic Strain ◽  
Contact Pressure ◽  
Contact Region ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Effective Plastic Strain ◽  
Normal Forces ◽  
Von Mises

When the load acting on a mechanical structure is greater than the yield strength of the material, the contact surface will undergo plastic deformation. Cumulative plastic deformation has an important influence on the lifespan of mechanical parts. This article presents a three-dimensional semi-analytical model based on the conjugate gradient method and fast Fourier transform algorithm, with the aim of studying the characteristic parameters of the contact region between a rigid ellipsoid and elasto-plastic half-space. Moreover, normal forces and tangential traction were considered, as well as the contact pressure resulting from various sliding speeds and friction coefficients. The contact pressure, effective plastic strain, von Mises stress, and residual stress were measured and shown to increase with increasing sliding velocity. Finally, when the friction coefficient, contact pressure, and effective plastic strain are increased, the von Mises stress is also shown to increase, whereas the residual stress decreases.

scholarly journals Experimental Investigation of Fully Plastic Contact of a Sphere Against a Hard Flat

2005 ◽  
Vol 128 (2) ◽  
pp. 230-235 ◽  
Author(s):  
J. Jamari ◽  
D. J. Schipper
Keyword(s):  
Experimental Investigation ◽  
Contact Pressure ◽  
Contact Area ◽  
Measurement Method ◽  
Contact Load ◽  
Model Predictions ◽  
The Mean

In this paper we report the experimental investigation to evaluate the published models for the contact of a deformable sphere against a hard flat in the fully plastic contact regime. A new measurement method has been used to measure the contact area. The behavior of the mean contact pressure and the contact area as a function of the contact load are presented. Substantial differences are found between the measurements and the model predictions. A constant value of the mean contact pressure as the load increases is observed, however, the value is lower than the hardness, as often reported. The contact area is found to be a simple truncation of the sphere by a hard flat.

Elastic-Plastic Finite Element Analysis of Indented Layered Media

1989 ◽  
Vol 111 (3) ◽  
pp. 430-439 ◽  
Author(s):  
K. Komvopoulos
Keyword(s):  
Finite Element ◽  
Plastic Zone ◽  
Contact Pressure ◽  
Critical Parameters ◽  
The Finite Element Method ◽  
Contact Pressure Distribution ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Substrate Properties ◽  
Layered Half Space

The elastic-plastic contact problem of a layered half-space indented by a rigid surface is solved with the finite element method. The case of a layer stiffer and harder than the substrate is analyzed and solutions for the contact pressure, subsurface stresses and strains, and location, shape, and growth of the plastic zone are presented for various layer thicknesses and indentation depths. Finite element results for a halfspace having the substrate properties are also given for comparison purposes. Differences between the elastic and elastic-plastic solutions are discussed and the significance of critical parameters such as the layer thickness, mechanical properties of layer and substrate materials, indentation depth, and interfacial friction on the threshold of plasticity, contact pressure distribution, and growth of the plastic zone are examined. Additionally, the mechanisms of layer decohesion and subsurface crack initiation are interpreted in light of the results obtained in this study.

Elastic-Plastic Contact Analysis of a Sphere and a Rigid Flat

2002 ◽  
Vol 69 (5) ◽  
pp. 657-662 ◽  
Author(s):  
L. Kogut ◽  
I. Etsion
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Contact Pressure ◽  
Contact Zone ◽  
Contact Area ◽  
Large Range ◽  
Element Model ◽  
Contact Interface ◽  
Frictionless Contact ◽  
Elastic Plastic

An elastic-plastic finite element model for the frictionless contact of a deformable sphere pressed by a rigid flat is presented. The evolution of the elastic-plastic contact with increasing interference is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. The model provides dimensionless expressions for the contact load, contact area, and mean contact pressure, covering a large range of interference values from yielding inception to fully plastic regime of the spherical contact zone. Comparison with previous elastic-plastic models that were based on some arbitrary assumptions is made showing large differences.

Validation on the Relationship Between J Integral and CTOD for Offshore Structural Steel Weldments by Experimental and Numerical Analyses

2014 ◽  
Author(s):  
Dong Hyun Moon ◽  
Jeong Soo Lee ◽  
Jae Myung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Plastic Deformation ◽  
Crack Tip ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Constraint Factor ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Constraint ◽  
The Relationship

Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis which considers extensive plastic deformation at crack tip prior to fracture. J integral and crack tip opening displacement (CTOD) have been commonly used as parameters for EPFM analysis. The relationship between these parameters has been extensively studied by industry and academia. The plastic constraint factor can serve as a parameter to characterize constraint effects in fracture involving plastic deformation. Therefore, the characteristics of plastic constraint factor are important in EPFM analysis. In this study, the relationship between J Integral and CTOD was investigated by conducting fracture toughness tests using single edge notched bend (SENB) specimens. Also, plastic constraint factor was investigated by using finite element analysis. Numerical analysis was carried out using ABAQUS elastic-plastic analysis mode.

Sign in / Sign up

Export Citation Format

Share Document