Influence of nonlinearities on the accuracy of the analytical solution for the shaft loaded blister test

Finite element analysis (FEA) is employed to study the effects of nonlinearities on the accuracy of the analytical solution for the shaft loaded blister test. The FEA model was validated using constrained blister test measurements showing a good correlation between the experimental and the FEA data. The analytical solution is then compared with the energy release rate obtained from J-integral evaluation in the FEA. For small and large shaft displacements deviations larger than 20% are encountered which is explained with the violation of the membrane limit condition and the onset of plasticity for larger displacements, respectively. Simplifications of the analytical solution are discussed using a random sampling method and it is shown that the thickness ratio between film and substrate can be neglected for thin films on rigid substrates. Further, values for the angular quantity, ω, which is required to calculate the mode mix phase angle are tabulated for the case of thin, elastic films on stiff substrates using a crack surface opening displacement extrapolation method.