Adhesion of elastic films on mound rough surfaces

In this work, we have investigated the adhesive behaviour of elastic films in contact with solid substrates, which are bounded by mound surface roughness. This type of roughness is described by the rms roughness amplitude w, the average mound separation Λ, and the system correlation length ζ. It is shown that both lateral roughness parameters Λ and ζ strongly influence adhesive characteristics. Indeed, with increasing elastic film modulus E, film adhesion is only possible for sufficiently large mound separations Λ. Moreover, the critical elastic modulus Ec (for which spontaneous film decohesion takes place for E>Ec) is shown to increase fast with increasing mound separation Λ when Λ⩽ζ, while as a function of the system correlation length ζ it increases relatively fast when ζ⩽Λ.