Tensile deformation finite plasticity

The separation of two surfaces in contact is resisted by adhesive forces. As the normal force is decreased, the contact regions pass from conditions of compressive to tensile stress. As revealed by JKR theory, surface tension alone is sufficient to ensure that there is a finite contact area between the two at zero normal force. One contribution to adhesion is the work that must be done to increase surface area during separation. If the surfaces have undergone plastic deformation, the contact area will be even greater at zero normal force than predicted by JKR theory. In reality, continued plastic deformation can occur during separation and also contributes to adhesive work. 

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