Formation of telephone cord blisters as a result of buckling delamination is widely observed in many compressed film-substrate systems. Here we report a universal morphological feature of such blisters characterized by their sequential sectional profiles exhibiting a butterfly shape using atomic force microscopy. Two kinds of buckle morphologies, light and heavy telephone cord blisters, are observed and differentiated by measurable geometrical parameters. Based on the Föppl-von Kármán plate theory, the observed three-dimensional features of the telephone cord blister are predicted by the proposed approximate analytical model and simulation. The latter further replicates growth and coalescence of the telephone cord into complex buckling delamination patterns observed in the experiment.

Fascinating pattern formation by quasi-static crack growth in thin films has received increasing interest in both interdisciplinary science and engineering applications.

Homogeneous wrinkling patterns such as labyrinths, herringbones and ripples can be widely observed in natural and artificial systems, but localized wrinkles (not delaminations, folds, ridges or creases) are seldom observed in experiments. Here we report on the spontaneous formation of highly ordered wrinkled stripes localized by cracks in metal films deposited on soft substrates.