Figure 4.

Effect of pre-tension on orientation-dependent adhesion of an elastic thin film/pad adhering to a substrate. (a) Peel-off force of the film as a function of the peeling angle at different levels of pre-tension. The presence of a pre-tension generally increases the peel-off force at low peeling angles. Beyond a critical pre-tension, the peel-off force plunges at a critical peeling angle. Solid curves represent the upper branch of the critical peel-off force, and dashed curves represent the lower branch of the peel-off force when it is positive. (b) Variation of the force-independent critical detachment angle as a function of the pre-tension magnitude. The critical angle exists only when the pre-tension exceeds $\sqrt{2EH\gamma }$.