Seminars

Wrinkling induced by instability of thin films has received intense attention in recent years owing to their important applications. There is also considerable interest in understanding the fundamental aspects of wrinkling. Most studies of the wrinkling only consider homogeneous films, either free-standing or bonded to a compliant substrate. However, heterogeneous films with microstructures widely exist in nature and engineering applications. Although the microstructures have an important role in determining the properties of materials or structures, there have been few studies on the wrinkling of microstructured thin films. In this study, we reveal the mechanism of the wrinkling of microstructured thin films and generate tailored wrinkle patterns by using microstructured thin films.

We investigate the effect of microstructures on the wrinkling of thin film by introducing different microstructures into a uniform free-standing film, including a pair of holes and periodic-arranged holes. Different kinds of wrinkle patterns under tension can be obtained by designing the position, radius, and arrangement of holes. Eigenvalue buckling analysis and stress analysis are performed to reveal the underlying mechanism: Microstructures change the distribution of stress field, effective mechanical properties, or internal interaction of the thin film, resulting in variations on the buckling mode and wrinkle pattern. A set of scaling laws for the wrinkle wavelength are obtained. Various wrinkle patterns or a suppression of wrinkles can be tailored by designing microstructured thin films in a controllable way, which may be applied in various disciplines such as flexible electronics, biomedical science, and aerospace engineering.