The Study Of Mechanics Models In The 3-Dimensional Indentation Delamination Test Of Thin Film/Substrate Systems

Based on Reissner plate theory, a novel model is proposed to analyze the buckling behavior of a circular delaminated thin film on an elastic substrate.When the aspect ratio of delamination size to film thickness is small,the shear deformation effect needs to be considered by using the medium plate theory. Elastic deformation in the substrate is taken into account by using three coupled-line-springs distributed along the edge of the delaminated film.The empirical formulae based on the finite element analysis are obtained for the stress intensity factors of interface crack in the film/substrate system.The paper also gives the empirical formula of the critical buckling stress, which is convenient for getting the value.The shooting method is used to solve the nonlinear post-buckling problem of the novel model.The critical buckling stress,energy release rate and phase angle are obtained.When the aspect ratio of delamination radius to film thickness is smaller than 10, the Reissner plate theory will give more accurate values in comparison with those corresponding values obtained from the classical plate theory.The impression zone could be fragmented in the test of brittle film, so the annular plate model based on the Reissner plate theory model is proposed to analyze the buckling problem.The shear deformation,elastic deformation and the inner radius of the annular plate are all taken into consideration.Comparing the results with those based on the circular plate model,it is found that the difference is obvious and the biggest difference of the energy release rate is nearly an order of magnitude.The influence of the inner radius of the annular delaminated film must be taken into account in order to make the calculating results more appropriate.