A Three-Dimensional Viscoelastic Analysis of Thin Film Delamination in a Peninsula Blister Specimen

The objective of this paper is to examine three-dimensional and viscoelastic effects in the peninsula blister test for thin film adhesion, which is considered an effective way to measure the interfacial fracture toughness of bonded thin film structures. As will be demonstrated in this paper, analytical solutions are sometimes inadequate for accurately simulating peninsula blister experiments because linear elastic behavior is assumed in the thin film as well as in the debonding process zone at the interface. For this purpose, a three- dimensional cohesive layer model and corresponding liquid loading simulation algorithm were developed and implemented into an in-house test-bed finite element analysis (FEA) code (NOVA-3D). Features such as three-dimensional mixed-mode debonding, large displacements and rotations, residual stresses in the thin film, and time-dependent (viscoelastic) effects in the thin film were considered. Numerical convergence and a stable debond growth were obtained over a fairly large debond length when suitably refined FEA mesh and liquid volume increment were employed. Detailed benchmark comparisons of the finite element predictions with analytical solutions and experimental results were performed, and good agreement was obtained.