Revisiting the Constrained Blister Test to Measure Thin Film Adhesion

A thin film is clamped at the periphery to form a circular freestanding diaphragm before a uniform pressure, p, is applied to inflate it into a blister. The bulging membrane adheres to a rigid constraining plate with height, w(0), from the nondeformed membrane. Increasing pressure expands the contact circle of radius, c. Depressurization causes shrinkage of the contact and "pull-off" or spontaneous detachment from the plate. Simultaneous measurement of (p, w(0), c) allows one to determine the adhesion energy, c. A solid mechanics model is constructed based on small strain and linear elasticity, which shows a characteristic loading-unloading hysteresis. The results are consistent with a large deformation model in the literature.