Adhesion between a spherical indenter and an elastic solid with a compliant elastic coating

The Johnson, Kendall and Roberts (JKR) adhesion theory is frequently applied to study the adhesion mechanics of thin compliant layers coated on to glass substrate in an atomic force microscope (AFM). These compliant layers are subjected to micro indentation in the AFM using a flat or spherical indenter. But, JKR theory is based on the contact of homogeneous, isotropic solids. The finite element analysis used by Sridhar er al (1997) (J. Phys. D; Appl. Phys. 30 1710-19) to study the adhesion mechanics of the three-layered crossed-cylinder arrangement of the surface force apparatus (SFA) has been extended to this AFM geometry. The effect of indenter elasticity is included for both spherical and flat punch probes. Computations of contact size and contact compliance each as a function of load are presented for a range of values of adhesion energy and elastic modulus ratio of layer and substrate.