M. Barquins et Mer. Shanahan, EFFECT OF SURFACE CAVITIES ON STATIC AND DYNAMIC ADHESION TO AN ELASTOMER, International journal of adhesion and adhesives, 17(4), 1997, pp. 313-317
The analysis of contact between two spherical surfaces introduced in t
he 19th century by Hertz was modified some 30 years ago by Johnson, Ke
ndall and Roberts (JKR) to allow for adhesion between the two solids.
Since then, the technique has jeer, much used with various systems emp
loying sphere/sphere and sphere/flat solid (sphere of infinite radius)
geometry. We consider here the geometry in which one solid has a nega
tive radius of curvature: a spherical solid contacts the second solid
in a shallow spherical cavity. It is thus shown that the contact area,
of a rigid sphere on the smooth surface of an elastomer depends marke
dly on the flatness of the latter. Any neglect of cavities of large ra
dius of curvature leads to an overestimate of the value of the intrins
ic adhesion of Dupre, W-0, and falsifies interpretation of separation
kinetics under (variable) ay,plied load. By allowing for the negative
radius of curvature of the cavities in the rubber, corrections can be
made leading to coherent values of W-0 and debonding kinetics. The ana
lysis may be of use for the assessment of flatness of surfaces and the
increase in contact radius may prove beneficial for improving the pre
cision of static adhesion tests. (C) 1998 Elsevier Science Ltd. All ri
ghts reserved.