Undulated blistering during thin film delamination.

We study the delamination of a compressed thin film from a solid substrate with continuum elasticity theory. Our model enables one to describe the advance of an undulated blister. It is shown that an elastic tension between the inner fold and the boundary of a blister is at the origin of the undulations. In addition, the essential experimental observations and recent simulations are reproduced very well: (i) Above a strain threshold, straight blister growth is unstable and starts to undulate. (ii) It is found that the period of the undulations scales with epsilon(-1/2), where epsilon() is the isotropic compressive strain of the film. (iii) Similar periodic corrections to this power law scaling are recovered and are found to be associated with a growth instability.