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Closed Form Nonlinear Analysis of the Peninsula Blister Test

Previous work by Liechti and Shirani [1] has shown that, among the family of blister tests, the peninsula blister test is the best because of low plastic deformation. This work further examines the peninsula blister test, derives new solutions, and accounts for residual stresses. An approximate nonlinear analysis of the peninsula blister based on the minimum potential energy method was developed for extracting the toughness of thin films bonded to stiff substrates. This analysis, which is easily applied to specimens with finite dimensions, was validated against an exact analytical solution for plane strain and a three-dimensional finite element analysis. Experiments with a film adhesive, Hysol EA 9696®, were conducted. Bulge tests were used to obtain the elastic properties of and the residual stresses in the film. The fracture experiments were used to check the solutions and determine the toughness of the bond between the adhesive and aluminum. In both experiments, in addition to the usual measurements of volume and pressure, the deflection of the specimen was measured using shadow moiré. This allowed the residual stresses to be determined and their effects on both membrane deflection and energy release rate to be examined.