Surface Wrinkling of Two Mutually Attracting Elastic Bodies due to van der Waals-like Interaction

Very recently [1], a new type of surface instability has been observed for compliant rubber-like elastic films interacting with a rigid flat plane through van der Waals-like attraction. The flat surface of the elastic film was found to become morphologically unstable when the interaction exceeds a critical value, and the instability mode is determined by the thickness of the elastic film, independently of its elastic modulus and the nature of the interaction. Motivated by some physical problems of current interest, a novel method is suggested in the present work to study this new surface instability for two mutually attracting elastic films [2], and for an elastic film interacting with a suspended elastic plate [3]. Among others, one major new result of [2, 3] is that the system consisting of two elastic layers could admit more than one metastable instability mode, in contrast to the unique instability mode of an elastic film interacting with a rigid flat surface [1]. It is anticipated that this non-uniqueness of the metasbale instability modes could cause complex surface instability phenomena, such as snap-through between two distinct instability modes and even chaotic behaviour under dynamic conditions.