Adhesion Of Elastic Solids Research Articles

Effect of the shape and size of interfacial micro-cavities on the adhesion of elastic solids

Microstructuring surfaces may strongly affect the adhesive behaviour at the contact interface, resulting in enhanced or weakened adhesion depending on the geometry of the surface structures and material properties. In this study we investigate the effects of size, shape and geometrical distribution of micro-cavities on the adhesion between an elastic solid and a rigid substrate. We show that reducing the lattice size by keeping constant the cavity size, may significantly weak the adhesion strength of the interface as a consequence of the interaction of the elastic stress and deformation fields generated by each single microcavity.

Adhesion between elastic bodies with rough surfaces

We study the influence of surface roughness on the adhesion of elastic solids. We present exact analytical results for a simple but fundamental model, and molecular dynamics results for different types of idealized surface roughness.

The effect of surface roughness on the adhesion of elastic solids

We study the influence of surface roughness on the adhesion of elastic solids. Most real surfaces have roughness on many different length scales, and this fact is taken into account in our analysis. We consider in detail the case when the surface roughness can be described as a self-affine fractal, and show that when the fractal dimension Df>2.5, the adhesion force may vanish, or be at least strongly reduced. We consider the block-substrate pull-off force as a function of roughness, and find a partial detachment transition preceding a full detachment one. The theory is in good qualitative agreement with experimental data.

Contact of elastic solids with rough surfaces

AbstractThe effect of surface roughness on the adhesion of elastic solids was examined with artificially roughened surfaces and crosslinked poly(dimethylsiloxane). The amplitudes (σ) and lateral correlation lengths (ξ) of the surface roughness were determined with the height–height correlation function calculated from atomic force microscopy images. The work of adhesion (W) did not change significantly for surfaces where σ ≤ 6 nm. However, with increasing σ and (ξ2/σ)1/3, W increased. Maximal adhesion was found for surfaces that produced the greatest indentation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1848–1854, 2001

The effect of surface roughness on direct wafer bonding

A theory is presented which describes the initial direct wafer bonding process. The effect of surface microroughness on the bondability is studied on the basis of the theory of contact and adhesion of elastic solids. An effective bonding energy, the maximum of which is the specific surface energy of adhesion, is proposed to describe the real binding energy of the bonding interface, including the influence of the wafer surface microroughness. Both the effective bonding energy and the real area of contact between rough surfaces depend on a dimensionless surface adhesion parameter, θ. Using the adhesion parameter as a measure, three kinds of wafer contact interfaces can be identified with respect to their bondability; viz. the nonbonding regime (θ >12), the bonding regime (θ <1), and the adherence regime (1<θ <12). Experimental data are in reasonable agreement with this theory.

The effect of surface topography on the adhesion of elastic solids

A study of the influence of surface roughness on the net work of adhesion when a smooth, high viscoelastic solid is first brought into contact with and then pulled away from a roughened Perspex surface. The work of adhesion was observed to be strongly dependent upon the rate at which these surfaces were pulled apart. The rate dependence of the adhesion could be calculated by normalizing the data obtained for the normally smooth surface. At small roughness value an increase in the adhesion was observed.

The effect of surface roughness on the adhesion of elastic solids

This paper describes a study of the adhesion between elastic solids and the effect of roughness in reducing the adhesion. The experiments were carried out between optically smooth rubber spheres and a hard smooth flat surface of Perspex which could be roughened to various degrees. The radius of the rubber spheres was varied by a factor of 8, their elastic modulus by a factor of 10, while the centre line average (c.l.a.)of the roughened Perspex surface was varied from 0.12 to 1.5 μm. The results show that c.l.a. roughnesses which are small compared with the overall deformation occurring at the region of the rubber-Perspex contact can produce an extremely large reduction in adhesion. The effect is more marked for rubbers of higher modulus. On the other hand the curvature of the sphere (over the range examined) has little influence. For this reason and because the analytical problem of a sphere on a rough flat is extremely complicated a theoretical analysis has been developed for the simpler case of a smooth flat in contact with a rough flat surface. As in Greenwood & Williamson (1966) the rough surface is modelled by asperities all of the same radius of curvature and with heights following a Gaussian distribution of standard deviation σ. The overall contact force is obtained by applying the contact theory of Johnson, Kendall & Roberts (1971) to each individual asperity. The theory predicts that the adhesion expressed as a fraction of the maximum value depends upon a single parameter, 1/Δ e ,which is the ratio between a and the elastic displacement δ C that the tip of an asperity can sustain before it pulls off from the other surface. The analysis shows that the adhesion parameter may also be regarded as representing the statistical average of a competition between the compressive forces exerted by the higher asperities trying to prize the surfaces apart and the adhesive forces between the lower asperities trying to hold the surfaces together. Although the theory is derived for two nominally plane surfaces it is found to fit the experimental results for a sphere on a flat reasonably well.

A note on the adhesion of elastic solids

A theoretical analysis is made of the stresses acting at the contact surface of two elastic spheres which are assumed to adhere to each other after the force pressing them together has been removed. The stress at the periphery of the contact area is shown to be tensile and infinite, so that adhesion is physically impossible; the spheres would peel apart. The theoretical results are consistent with the experimental work of Bowden and Tabor.