Plane-strain, buckling-driven delamination of thin films: Model experiments and mode-II fracture

A series of model experiments have been conducted to compare observations on buckling-driven delamination of thin films under plane-strain compression with an existing analysis. The results are consistent within the range considered by the theory, which applies when the delamination crack is open to the tip. However, the observations indicate that delamination can occur beyond this range, when the crack tip is closed and undergoing mode-II advance. The theory was extended to incorporate the effect of a contact region in which frictional effects shields the crack tip. A comparison of the analysis with the data indicates that the frictional stress required to explain the apparent toughness observed in this regime is larger than the shear yield strength of the interface. It is inferred that large-scale plasticity may have a significant effect on the results, but this effect has not been included in the analysis.