Adhesive impact of micromechanical surface contact (original) (raw)
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Adhesional friction law and adhesive wear law of micromechanical surface contact
The paper describes the investigation on adhesional friction law and adhesive wear law of micromechanical surface contact. Adhesion theory of loading force and friction force is incorporated in multiasperity contact to find out static coefficient of friction which supports Amontons's law of friction. New adhesive wear law is developed from almost linear relationship of dimensionless real area of contact and dimensionless adhesive wear volume, and it is compared with existing Archard's adhesive wear law.
Adhesive wear theory of micromechanical surface contact
Microscopically, when two surfaces come in contact, strong adhesive bond is formed at the tip of the asperities and consequently, adhesive wear particle is formed by shearing the interface caused by sliding. On the basis of JKR adhesion theory, dimensionless real area of contact and wear volume are computed numerically for multiasperity contact and It is found, their ratio is almost constant for different pair of MEMS surfaces. From which adhesive wear law is derived and accordingly, adhesive wear volume is the multiplication of real area of contact and rms roughness (sigma).
Adhesive Contact Deformation of a Single Microelastomeric Sphere
Journal of Colloid and Interface Science, 1998
The current work reports primarily on an experimental This paper reports on an experimental study of the adhesive study, with associated theoretical analyses, of the comprescontact of a single microscopic (about 300 mm) elastomer sphere sive deformation behavior of microscopic elastic polymer compressed between two smooth parallel glass platens at small spheres at a small range-imposed strain in ambient air. For imposed deformations. An experimental arrangement that allows a nonadhesive elastic sphere compressed between two paralthe simultaneous measurement of the compressive displacements lel flat platens, the force resisting this deformation depends and the reaction forces is described. A number of interesting pheupon the approach (half of the compressive displacement at nomena, including the pull-off separation and the ''jump'' contact the pole of the deformed sphere) to the 3/2 power for small phenomena of the microsphere and the moving platen supported by a cantilever, are shown in the experimental force-displacement deformations. The theoretical nature of this relationship was curve of a loading and unloading cycle. The pull-off forces are originally described in detail by Hertz and allows the demonstrated to not depend upon the applied dimensionless apdeformation of the sphere in the region of the contacting proach (compressive displacement/initial particle diameter), platens to be fully described, subject to a number of imwhile they increase with the increasing rate at which the interfaces portant assumptions. The principal assumptions are that a are separated. The predictions of an established contact mechaninormally loaded contact exists between the bodies, that the cal adhesive theory, Johnson-Kendall-Roberts (JKR) theory, in material behaves as a linear elastic body, that the radius of which the influence of the surface energy on the contact has been contact area is small compared with the radius of the sphere, taken into account, are in good agreement with these experimental and that there is frictionless contact between the surfaces results. An application of the JKR analysis to the pull-off force resulting in the transfer of only normal stresses between the provides a reasonable estimate of the interfacial free energy of the contact. ᭧ 1998 Academic Press contacting surfaces.
Normal impact of rough surfaces in presence of adhesion
Tribology International, 2004
The paper describes a theoretical study of normal impact between solids with small-scale surface asperities. An elastic-plastic impact model is used to study the normal impact between rough surfaces in presence of surface forces. The well-established elastic and plastic adhesion indices are used to consider the different conditions arising out of varying impact velocity and material parameters. The study shows that the coefficient of restitution is affected by material-properties, surface-topography and impact velocity. Results clearly indicate that high impact velocity is desirable in order to achieve low coefficient of restitution. However, there are certain combinations of material properties and surface conditions, given by the choice of adhesion indices, where coefficient of restitution falls to a very low value. #
Adhesional friction theory of micromechanical surface contact
When two rough surfaces come in contact, tip of asperities would adhere and produces resistance as friction during sliding. First Bowden and Tabor has developed adhesional friction theory based on concept of cold welding of asperity tip through plastic deformation and flow. But this simple theory could not explain for adhesional friction of lightly loaded, clean and smooth hard metallic surface contact (Like MEMS) where asperities deform elastically. In this regard, an alternative adhesional friction theory is developed based on concept of cold welding of asperity through intermolecular adhesion at the area of contact considering JKR and SB adhesion theory of elastic solid sphere.
Numerical simulations of the normal impact of adhesive microparticles with a rigid substrate
Powder Technology, 2009
The rebound behavior of elastic and elastoplastic microspheres impacting normally with a rigid wall is studied using the finite element method. The interfacial adhesion forces are introduced by adding piecewiselinear spring elements with a particular constitutive relation characterizing the adhesion property. The effect of adhesion hysteresis is taken into account by assuming that the adhesion work during the incident stage is smaller than that during rebounding. The influences of the interfacial adhesion parameters, the constitutive relations, size, and incident velocity of the particle on the coefficient of restitution (COR) are all examined. We also analyze the changing tendency of the kinetic energy, elastic strain energy, adhesion work, and their interchange during impact. It is found that besides interfacial adhesion and plastic dissipation, the residual stress field caused by incompatible plastic deformation has a considerable influence on the impact behavior of the sphere as well. For smaller impact velocities, interfacial adhesion plays a dominant role in the impact process, while for higher incident velocities, the COR depends mainly on plastic deformation. In addition, the COR shows a distinct dependence on the particle size. Finally, our numerical results are compared with the relevant experimental results.
Langmuir, 1997
Adhesion measurements based on the fracture mechanics analysis of Johnson, Kendall, and Roberts (JKR) provide a very convenient method for measuring the energy of adhesion, G, for elastomeric materials against a variety of substrates. The JKR approach utilizes linear elastic fracture mechanics, and is based on the assumptions that the contact geometry is characterized by a single radius of curvature, and that the relevant dimensions of the adhering bodies are large compared to the dimensions of the contact area. The assumption of large sample size is not necessarily valid for the commonly employed geometry consisting of a soft, spherical cap pressed against a flat, rigid surface. The implications of the resultant finite-size corrections are studied here using two different model systems: a cross-linked poly(n-butyl acrylate) homopolymer and a gel made from an acrylic triblock copolymer diluted with 2-ethylhexanol. The compliance of the spherical caps is found to deviate significantly from the value assumed in a standard JKR analysis. This discrepancy is independent of the contact area, however. Determinations of the fracture energy which are based on the relationship between the load and contact area are, therefore, not affected by this correction to the compliance. The modified compliance does need to be accounted for when the fracture energy is determined from the relationship between the contact area and the relative displacements of the adhering bodies. Use of this relationship is shown to provide a particularly powerful method for determining the modulus and/or adhesion energy for low-modulus solids.
Adhesive Joints Subjected to Impact Loading: A Review
International Journal of Materials Engineering, 2019
Adhesive joints have widely been used in many engineering applications due to their outstanding advantages over conventional joining methods. Developing strong adhesive bonds lead adhesive joints to be a very popular joining methods in the applications subjected to impact loadings. Especially, the automotive industry uses adhesive joints in order to reduce the weight of vehicles by bonding multilayer lightweight materials. Understanding the performance of adhesive joints subjected to impact loadings is significant to apply them into the applications that may be exposed to high loading rates. Even though there are many researches on characterizing the performance of adhesive joints subjected to quasi-static loading in the literature, there are few studies focused on the performance of adhesive joints under impact loading. In this paper, the researches on adhesive joints under high loading rates are reviewed. The different testing techniques of adhesive joints subjected to impact load...
Adhesive contact of elastic spheres revisited: numerical models and scaling
… of the Royal …, 2009
For the purpose of determining the relevant scaling, the fundamental and widely applicableproblem of adhesive contact between elastic solids is revisited. A comprehensive and accurate finite-element modelling is undertaken. A local contact law, consistent with the current level of modelling, is used. The analysis of the results yields the following conclusions. For a broad range of physically reasonable contact laws, and for low values of the Tabor parameter, a simple modification of adhesive range entering in the Tabor parameter allows for one-parameter scaling of the problem. For high values of the modified Tabor parameter, the problem requires description in terms of two non-dimensional parameters, one of which represents the magnitude of the contact surface stretch. The contact surface stretch correction is significant for a wide range of problems with spheres smaller than the threshold size, which, for a broad range of materials, is 300 nm to 100 microns, depending on the adhesive energy and elastic compressibility.