Effect of substrate compliance on the global unilateral post-buckling of coatings: AFM observations and finite element calculations

The post-critical regime of straight-sided wrinkles on compliant substrates of polycarbonate has been observed by atomic force microscope and investigated by means of finite element simulations. The effect of coupling between the film and its substrate has revealed a global buckling phenomenon, characterized by critical loads lower than those found in the case of a rigid substrate. Characteristic shapes of the buckled structure have been also found to spread over a region wider than the delaminated zone itself. A law relating the film deflexion to the stress has finally been established for any film/substrate system.