Wrinkled stripes localized by cracks in metal films deposited on soft substrates.

Abstract

Homogeneous global wrinkling patterns such as labyrinths, herringbones, ripples and straight stripes can be widely observed in natural and artificial systems, but localized wrinkling patterns (not including buckle-driven delaminations, folds, ridges and 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. The experiment shows that the metal film is under a large tensile stress during deposition, which is relieved by the formation of networked cracks. After deposition, a compressive stress is stored up in the film and it always focuses near the new formed cracks due to the plastic deformation of the film, resulting in the formation of localized wrinkled stripes composed of a large number of straight wrinkles perpendicular to the cracks. The morphological characteristic, formation mechanism and evolution behaviors of the localized wrinkled stripes have been described and discussed in detail.