Determination of the energy dissipated during peel testing

During the experimental determination of adhesion strength through a peel test, the deformation energy of the peeled foil, plus frictional losses may constitute a significant portion of the total peel energy. When the true adhesion strength is desired, the energy dissipated in bending of the foil has to be found, whether experimentally or analytically, and deducted from the total peel energy. Several works were dedicated to the modeling and calculation of the energy dissipated through plastic deformation so that the net adhesion energy could be deduced. Recently, the present authors proposed a simple experimental technique for the determination of the net adhesion strength. The method is not limited to any particular material and can be used successfully for a strain hardening plastic as well as metallic foils. In this work the calculation of the various energy terms dissipated during the peel test is carried out, in order to validate the results of the experimental method and to study the effect of the test variables, such as geometry and mechanical properties of the flexible foil. The main parameter that influences the energy expended during the test is the radius of curvature of the flexible adherend. It is found that the ratio of the total energy to the adhesion energy versus this radius of curvature behaves in a complex manner. For a low strength material, the ratio increases with the radius of curvature. For high strength materials, the ratio exhibits a critical radius, at which the ratio is maximal.