scholarly journals Гистерезис в адгезионном контакте при изменении направления сдвига: эксперимент и феноменологическая модель

2021 ◽  
Vol 91 (4) ◽  
pp. 689
Author(s):  
Я.А. Ляшенко ◽  
В.Л. Попов
Keyword(s):  
Adhesive Strength ◽  
Contact Time ◽  
Indentation Depth ◽  
Adhesive Contact ◽  
Hysteretic Behavior ◽  
Contact Radius ◽  
Contact Strength ◽  
Rubber Sheet ◽  
Theoretical Results ◽  
Soft Elastomer

A phenomenological model is proposed that describes hysteretic behavior of an adhesive contact between a soft elastomer and a rigid indenter when the direction of the indenter shear is changed. The model takes into account the increase of contact strength with contact time. The dependences of the elastic force and contact radius on the indentation depth were obtained. It is shown that the adhesive strength of the contact increases with an increase in the indentation depth. An experiment on the indentation of a steel spherical indenter into a rubber sheet of a fixed thickness was carried out. A qualitative agreement between the experimental and theoretical results is shown.

scholarly journals Влияние продолжительности контакта и глубины индентирования на адгезионную прочность: эксперимент и численное моделирование

2020 ◽  
Vol 90 (10) ◽  
pp. 1769
Author(s):  
Я.А. Ляшенко ◽  
В.Л. Попов
Keyword(s):  
Numerical Simulation ◽  
Satisfactory Agreement ◽  
Adhesive Strength ◽  
Glass Substrate ◽  
Indentation Depth ◽  
Adhesive Contact ◽  
Spherical Indenter ◽  
Experimental Results ◽  
Fixed Load ◽  
Soft Rubber

The adhesive contact between a steel spherical indenter and a layer of transparent soft rubber fixed on a glass substrate is experimentally investigated. Obtained experimental results are compared with theory and numerical simulation, which demonstrates satisfactory agreement between these three approaches. The influence of the indenter time in the contact and the indentation depth on the value of the adhesive strength of the contact is studied. The features of experiments conducted under conditions of controlled displacement (fixed grips) and controlled force (fixed load) are discussed.

Thermodynamic aspects of epitaxial self-assembly and magnetoelectric response in multiferroic nanostructures

2007 ◽  
Vol 22 (8) ◽  
pp. 2087-2095 ◽  
Author(s):  
Julia Slutsker ◽  
Zhuopeng Tan ◽  
Alexander L. Roytburd ◽  
Igor Levin
Keyword(s):  
Electric Fields ◽  
Self Assembly ◽  
Electromagnetic Coupling ◽  
Hysteretic Behavior ◽  
Microscopic Mechanism ◽  
Magnetic Nanorods ◽  
External Electric Fields ◽  
Multiferroic Films ◽  
Magnetoelectric Response ◽  
Theoretical Results

A thermodynamic approach was used to describe the formation and magnetoelectric response of composite multiferroic films. Experimental and theoretical results that address the origins of different phase morphologies in epitaxial spinel-perovskite nanostructures grown on differently oriented substrates are presented. A theoretical model of magnetoelectric coupling in multiferroic nanostructures that considers a microscopic mechanism of magnetization in single-domain magnetic nanorods is described. This model explains a discontinuous electromagnetic coupling, as observed experimentally, and predicts a hysteretic behavior of magnetization under external electric fields.

AN APPROXIMATE FORMULATION OF THE EFFECTIVE INDENTATION MODULUS OF ELASTICALLY ANISOTROPIC FILM-ON-SUBSTRATE SYSTEMS

2009 ◽  
Vol 01 (03) ◽  
pp. 515-525 ◽  
Author(s):  
T. L. LI ◽  
J. H. LEE ◽  
Y. F. GAO
Keyword(s):  
Applied Load ◽  
Indentation Depth ◽  
Surface Displacement ◽  
Contact Radius ◽  
Radial Coordinate ◽  
Indentation Modulus ◽  
Approximate Formulation ◽  
Punch Contact ◽  
Indenter Shape ◽  
Circular Contact

Frictionless contact between an arbitrarily-shaped rigid indenter and an elastically anisotropic film-on-substrate system can be regarded as being superposed incrementally by a flat-ended punch contact, the shape and size of which are determined by the indenter shape, indentation depth (or applied load) and elastic properties of film and substrate. For typical nanoindentation applications, the indentation modulus can thus be approximated from the response of a circular contact with pressure of the form of [1 - (r/a)2]-1/2, where r is the radial coordinate and a is the contact radius. The surface-displacement Green's function for elastically anisotropic film-on-substrate system is derived in closed-form by using the Stroh formalism and the two-dimensional Fourier transform. The predicted dependence of the effective modulus on the ratio of film thickness to contact radius agrees well with detailed finite element simulations. Implications in evaluating film modulus by nanoindentation technique are also discussed.

Nanoindentation Method for Determining the Initial Contact and Adhesion Characteristics of Soft Polydimethylsiloxane

2005 ◽  
Vol 20 (8) ◽  
pp. 2004-2011 ◽  
Author(s):  
Yifang Cao ◽  
Dehua Yang ◽  
Wole Soboyejoy
Keyword(s):  
Indentation Depth ◽  
Contact Point ◽  
Nonlinear Least Squares ◽  
Soft Materials ◽  
Work Of Adhesion ◽  
Contact Radius ◽  
Initial Contact ◽  
Combined Use ◽  
Fitting In ◽  
Load Indentation

In this paper, we present a method for determining the initial contact point and nanoindentation load–indentation depth characteristics for soft materials. The method is applied to the prediction of the load–indentation depth characteristics of polydimethylsiloxane. It involves the combined use of Johnson–Kendall–Roberts and Maugis–Dugdale adhesion theories and nonlinear least squares fitting in the determination of the initial contact point, the transition parameter, and the contact radius at zero contact load. The elastic modulus and the work of adhesion are also extracted from the load–indentation depth curves.

An Extension to a Cohesive Zone Solution for Adhesive Cylinders

2004 ◽  
Author(s):  
Clint A. Morrow ◽  
Michael R. Lovell
Keyword(s):  
Cohesive Zone ◽  
Normal Load ◽  
Adhesive Contact ◽  
Physical Contact ◽  
Contact Radius ◽  
Intimate Contact ◽  
Contact Behavior ◽  
Micro Scale ◽  
Applied Normal Load ◽  
Adhesive Forces

When adhesive forces are taken into consideration, contacting asperities can still interact after intimate contact is broken. Current theories that predict the contact behavior of adhesive cylindrical asperities fail to capture the forces in this regime. In the present investigation, prior solutions for adhesive cylindrical asperities will be extended to include the condition where the asperities are not in physical contact but are still interacting through adhesive forces. In the extended results, relationships between the adhesive contact radius and the applied normal load will be developed and discussed with respect to the design of micro-scale components.

A Unified Treatment of Axisymmetric Adhesive Contact on a Power-Law Graded Elastic Half-Space

2013 ◽  
Vol 80 (6) ◽  
Author(s):  
Fan Jin ◽  
Xu Guo ◽  
Wei Zhang
Keyword(s):  
Half Space ◽  
Power Law ◽  
Contact Region ◽  
Adhesive Contact ◽  
Elastic Half Space ◽  
Hertzian Contact ◽  
Contact Radius ◽  
Abel Transformation ◽  
Numerical Solution Methods ◽  
Special Cases

In the present paper, axisymmetric frictionless adhesive contact between a rigid punch and a power-law graded elastic half-space is analytically investigated with use of Betti's reciprocity theorem and the generalized Abel transformation, a set of general closed-form solutions are derived to the Hertzian contact and Johnson–Kendall–Roberts (JKR)-type adhesive contact problems for an arbitrary punch profile within a circular contact region. These solutions provide analytical expressions of the surface stress, deformation fields, and equilibrium relations among the applied load, indentation depth, and contact radius. Based on these results, we then examine the combined effects of material inhomogeneities and punch surface morphologies on the adhesion behaviors of the considered contact system. The analytical results obtained in this paper include the corresponding solutions for homogeneous isotropic materials and the Gibson soil as special cases and, therefore, can also serve as the benchmarks for checking the validity of the numerical solution methods.

Adhesive Contact of Bodies Having an Elliptical Contact Area

2005 ◽  
Author(s):  
K. L. Johnson ◽  
J. A. Greenwood
Keyword(s):  
Closed Form ◽  
Contact Area ◽  
Adhesive Contact ◽  
Contact Radius ◽  
General Shape ◽  
Elliptical Contact ◽  
Jkr Theory ◽  
Two Bodies

The so-called JKR theory of adhesion between elastic spheres in contact (Johnson, Kendall & Roberts 1971, Sperling 1964) has been widely used in micro-tribology. In this paper the theory is extended to solids of general shape and curvature. It is assumed that the area of contact is elliptical which turns out to be approximately true, though the eccentricity is different from that for non-adhesive contact. Closed form expressions are found for the variation with load of contact radius and displacement, as a function of the ratio of principal relative curvatures of the two bodies in contact. The pull-off force is found to decrease with increasing eccentricity from its value of 3πΔγR/2 in the case of contact of spheres of radius R.

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.

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