Evaluation of Transverse Shear Effect on Film Delamination in Blister Test

The transverse shear effect has been frequently ignored in determining the debonding-related energy release rate and the phase angle in the blister test, resulting in underestimated values. This study aims to study the effect of shear force on the energy release rate and phase angle prediction in the blister test. A generalized approach is proposed to predict them under the effect of shear force. The predictions show that when the ratio of the film thickness to the debonded film window radius is large (such as 0.05), the transverse shear effect cannot be ignored in determining the energy release rate and the phase angle. The study also further illustrates the importance of including the shear force contribution in estimation and how this importance depends on the film thickness to debonded radius ratio, as well as the elastic mismatch.