Loading-Unloading of an Elastic-Plastic Adhesive Spherical Contact

2008 ◽  
Author(s):  
Yuri Kadin ◽  
Yuri Kligerman ◽  
Izhak Etsion
Keyword(s):  
Kinematic Hardening ◽  
Adhesive Contact ◽  
Isotropic Hardening ◽  
Jones Potential ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Linear Spring ◽  
Two Parameters ◽  
Plasticity Parameter ◽  
Force Displacement

A numerical solution is presented for a single load-unload cycle of an adhesive contact between an elastic-plastic sphere and a rigid flat. The interacting forces between the sphere and the flat are obtained through connecting non-linear spring elements having force-displacement behavior that obeys the Lennard-Jones potential. Linear kinematic hardening (with tangent modulus of 2% and 5% of the Young’s modulus) rather than isotropic hardening is assumed for the sphere material to account for possible secondary plastification during the unloading. The well known Tabor parameter and a plasticity parameter are shown to be the two main dimensionless parameters governing the problem. The effects of these two parameters on the load-approach curves, on the plastically deformed sphere profiles and on the plastic strain fields inside the sphere are presented, showing different modes of separation during the unloading.

3-D Elastic-Plastic Constitutive Relationship of Mixed Hardening

2012 ◽  
Vol 249-250 ◽  
pp. 927-930
Author(s):  
Ze Yu Wu ◽  
Xin Li Bai ◽  
Bing Ma
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Kinematic Hardening ◽  
Constitutive Relationship ◽  
Isotropic Hardening ◽  
Element Analysis ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Mixed Hardening ◽  
Advantages And Disadvantages

In finite element calculation of plastic mechanics, isotropic hardening model, kinematic hardening model and mixed hardening model have their advantages and disadvantages as well as applicability area. In this paper, by use of the tensor analysis method and mixed hardening theory in plastic mechanics, the constitutive relation of 3-D mixed hardening problem is derived in detail based on the plane mixed hardening. Numerical results show that, the proposed 3-D mixed hardening constitutive relation agrees well with the test results in existing references, and can be used in the 3-D elastic-plastic finite element analysis.

scholarly journals Effect of Strain Hardening on Elastic-Plastic Contact of a Deformable Sphere against a Rigid Flat under Full Stick Contact Condition

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Biplab Chatterjee ◽  
Prasanta Sahoo
Keyword(s):  
Strain Hardening ◽  
Kinematic Hardening ◽  
Contact Condition ◽  
Isotropic Hardening ◽  
Contact Conditions ◽  
Elastic Plastic ◽  
Finite Element Software ◽  
Hardening Models ◽  
Load Carrying ◽  
Contact Parameters

The present study considers the effect of strain hardening on elastic-plastic contact of a deformable sphere with a rigid flat under full stick contact condition using commercial finite element software ANSYS. Different values of tangent modulus are considered to study the effect of strain hardening. It is found that under a full stick contact condition, strain hardening greatly influences the contact parameters. Comparison has also been made between perfect slip and full stick contact conditions. It is observed that the contact conditions have negligible effect on contact parameters. Studies on isotropic and kinematic hardening models reveal that the material with isotropic hardening has the higher load carrying capacity than that of kinematic hardening particularly for higher strain hardening.

Contact and Adhesion of Elastic-Plastic Layered Microsphere

2010 ◽  
Author(s):  
H. Eid ◽  
L. Chen ◽  
N. Joshi ◽  
N. E. McGruer ◽  
G. G. Adams
Keyword(s):  
Layer Thickness ◽  
Plastic Material ◽  
Adhesive Contact ◽  
Contact Radius ◽  
Jones Potential ◽  
Elastic Plastic ◽  
High Durability ◽  
Loading And Unloading ◽  
Elastic Plastic Material ◽  
Maximum Contact

A finite element contact model of a layered hemisphere with a rigid flat, which includes the effect of adhesion, is developed. This configuration has been suggested as a design for a microswitch contact because it has the potential to achieve low adhesion, low contact resistance, and high durability. Elastic-plastic material properties were used for each of the materials comprising the layered hemisphere. Adhesion was modeled based on the Lennard-Jones potential. The effect of the layer thickness on the adhesive contact was investigated. In particular the influence of layer thickness on the pull-off force and maximum contact radius was studied. The results are presented as load vs. interference and contact radius vs. interference for loading and unloading from different values of the maximum interference.

Cyclic Loading of an Elastic-Plastic Adhesive Contact

2008 ◽  
Author(s):  
Y. Kadin ◽  
Y. Kligerman ◽  
I. Etsion
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Cyclic Loading ◽  
Contact Interaction ◽  
Adhesive Contact ◽  
Cyclic Plasticity ◽  
Electric Contact ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Mems Device

A numerical simulation is presented for several loading-unloading cycles of an adhesive contact between an elastic-plastic sphere and a rigid flat. The main goal of the simulation is to study the plastic deformation evolution in a contact bump material — the microscopic electrode found in a MEMS micro-switch for providing a good electric contact. This bump is subjected to a cyclic contact interaction with a harder substrate and cyclic plasticity of the bump material can lead to its wear and as result to a failure of the whole MEMS device.

Adhesive Contact of Elastic-Plastic Layered Media: Effective Tabor Parameter and Mode of Surface Separation

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Z. Song ◽  
K. Komvopoulos
Keyword(s):  
Layer Thickness ◽  
Material Properties ◽  
Layered Medium ◽  
Adhesive Contact ◽  
Rigid Sphere ◽  
Maximum Surface ◽  
Elastic Plastic ◽  
Surface Separation ◽  
Plasticity Parameter ◽  
Tabor Parameter

Adhesive contact of a rigid sphere with a layered medium consisting of a stiff elastic layer perfectly bonded to an elastic-plastic substrate is examined in the context of finite element simulations. Surface adhesion is modeled by nonlinear spring elements obeying a force-displacement relation governed by the Lennard–Jones potential. Adhesive contact is interpreted in terms of the layer thickness, effective Tabor parameter (a function of the layer thickness and Tabor parameters corresponding to layer and substrate material properties), maximum surface separation, layer-to-substrate elastic modulus ratio, and plasticity parameter (a characteristic adhesive stress expressed as the ratio of the work of adhesion to the surface equilibrium distance, divided by the yield strength of the substrate). It is shown that surface separation (detachment) during unloading is not encountered at the instant of maximum adhesion (pull-off) force, but as the layered medium is stretched by the rigid sphere, when abrupt surface separation (jump-out) occurs under a smaller force (surface separation force). Ductile- and brittle-like modes of surface detachment, characterized by the formation of a neck between the rigid sphere and the layered medium and a residual impression on the unloaded layered medium, respectively, are interpreted for a wide range of plasticity parameter and maximum surface separation. Numerical results illustrate the effects of layer thickness, bulk and surface material properties, and maximum surface separation (interaction distance) on the pull-off and surface separation forces, jump-in and jump-out contact instabilities, and evolution of substrate plasticity during loading and unloading. Simulations of cyclic adhesive contact demonstrate that incremental plasticity (ratcheting) in the substrate is the most likely steady-state deformation mechanism under repetitive adhesive contact conditions.

Elastic-plastic finite element analysis of hollow tubes with axially loaded axisymmetric internal projections

1993 ◽  
Vol 28 (3) ◽  
pp. 187-196 ◽  
Author(s):  
S J Hardy ◽  
A R Gowhari-Anaraki
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Elastic Stress ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Published Data ◽  
Elastic Plastic ◽  
Concentration Factors ◽  
Stress Concentration Factors

The finite element method is used to study the monotonic and cyclic elastic-plastic stress and strain characteristics of hollow tubes with axisymmetric internal projections subjected to monotonic and repeated axial loading. Two geometries having low and high elastic stress concentration factors are considered in this investigation, and the results are complementary to previously published data. For cyclic loading, three simple material behaviour models, e.g., elastic-perfectly-plastic, isotropic hardening, and kinematic hardening are assumed. All results have been normalized with respect to material properties so that they can be applied to all geometrically similar components from other materials which may be represented by the same material models. Finally, normalized maximum monotonic strain and steady state strain range, predicted in the present investigation and from previously published data, are plotted as a function of the nominal load for different material hardening assumptions and different elastic stress concentration factors. These plots can be used in the low cycle fatigue design of such geometrically similar components.

Elastic-Plastic Modeling of Hardening Materials Using a Corotational Rate Based on the Plastic Spin Tensor

2007 ◽  
Author(s):  
Kamyar Ghavam ◽  
Reza Naghdabadi
Keyword(s):  
Kinematic Hardening ◽  
Deformation Gradient ◽  
Isotropic Hardening ◽  
Strain Rate Tensor ◽  
Spin Tensor ◽  
Plastic Spin ◽  
Elastic Plastic ◽  
Proposed Model ◽  
Corotational Rate ◽  
Shear Problem

In this paper based on the multiplicative decomposition of the deformation gradient, the plastic spin tensor and the plastic spin corotational rate are introduced. Using this rate (and also log-rate), an elastic-plastic constitutive model for hardening materials are proposed. In this model, the Armstrong-Frederick kinematic hardening and the isotropic hardening equations are used. The proposed model is solved for the simple shear problem with the material properties of the stainless steel SUS 304. The results are compared with those obtained experimentally by Ishikawa [1]. This comparison shows a good agreement between the results of proposed theoretical model and the experimental data. As another example, the Prager kinematic hardening equation is used. In this case, the stress results are compared with those obtained by Bruhns et al. [2], in which they used the additive decomposition of the strain rate tensor.

Theoretical and Experimental Investigation of Plastic Hysteresis in Spherical Contact Under Combined Normal and Tangential Loading

2008 ◽  
Author(s):  
Yuri Kligerman ◽  
Andrey Ovcharenko ◽  
Izhak Etsion ◽  
Gregory Halperin
Keyword(s):  
Experimental Investigation ◽  
Theoretical Model ◽  
Stress State ◽  
Contact Area ◽  
Kinematic Hardening ◽  
Contact Condition ◽  
Tangential Displacement ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Good Agreement

The behavior of an elastic-plastic contact between a deformable sphere and a rigid flat under combined constant normal and reciprocating tangential loading is investigated theoretically and experimentally. The theoretical model is based on the assumptions of full stick contact condition and elastic–linear kinematic hardening of the sphere material. Hysteretic change of friction force versus tangential displacement during reciprocating tangential loading is investigated along with the study of the change of the contact area and stress state in the elastic-plastic sphere. Good agreement between theoretical and experimental results is obtained.

scholarly journals Configurational forces in cyclic metal plasticity

2019 ◽  
Vol 300 ◽  
pp. 08009
Author(s):  
Aris Tsakmakis ◽  
Michael Vormwald
Keyword(s):  
Driving Force ◽  
Plastic Material ◽  
Kinematic Hardening ◽  
Yield Function ◽  
Configurational Forces ◽  
Isotropic Hardening ◽  
Crack Driving Force ◽  
Metal Plasticity ◽  
Elastic Plastic ◽  
Von Mises

The configurational force concept is known to describe adequately the crack driving force in linear fracture mechanics. It seems to represent the crack driving force also for the case of elastic-plastic material properties. The latter has been recognized on the basis of thermodynamical considerations. In metal plasticity, real materials exhibit hardening effects when sufficiently large loads are applied. Von Mises yield function with isotropic and kinematic hardening is a common assumption in many models. Kinematic and isotropic hardening turn out to be very important whenever cyclic loading histories are applied. This holds equally regardless of whether the induced deformations are homogeneous or non-homogeneous. The aim of the present paper is to discuss the effect of nonlinear isotropic and kinematic hardening on the response of the configurational forces and related parameters in elastic-plastic fracture problems.

Descriptions of reversed yielding of a solid circular bar in torsion

2008 ◽  
Vol 223 (3) ◽  
pp. 557-571 ◽  
Author(s):  
D W A Rees
Keyword(s):  
Flow Stress ◽  
Kinematic Hardening ◽  
Outer Radius ◽  
The Other ◽  
Isotropic Hardening ◽  
Stress Distributions ◽  
Initial Yield Stress ◽  
Elastic Plastic ◽  
Special Cases ◽  
Core Conditions

Two plastic penetrations are possible from applying torque to a solid, circular-section bar: one from applying an elastic—plastic torque and the other from releasing it. The first penetration occurs from the outer radius inwards towards the centre when the deformation becomes increasingly plastic as the flow stress increases beyond the initial yield stress. The second plastic penetration occurs in a similar manner but is a manifestation of the Bauschinger effect, which refers to that reduction in the flow stress required to initiate reversed plasticity. The latter can occur upon the release of the elastic—plastic torque responsible for an initial plastic penetration, usually deeper than the mean radius. A theory of secondary penetration is given for both linear and parabolic hardening materials. By varying the plastic tangent modulus special cases of linear hardening are studied, including ideal materials with perfect (forward) plasticity and those that obey kinematic hardening. Within the chosen hardening law the elastic and plastic strains are developed from the bar's angular twist within its elastic core. Conditions, for which a torque-release is either purely elastic or elastic—plastic, appear to be within the section parameters and the material's flow curve, these providing the depth of a secondary penetration. Two stress distributions, one for the application of torque and the other for torque release, are sufficient to show that residual stress distributions differ from non-hardening theory. Experimental results given suggest that residuals arising from parabolic hardening are more realistic where a second penetration occurs. Experiment also reveals where kinematic and isotropic hardening models apply.

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