Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States.
School of Engineering and Applied Sciences, Kavli Institute for Bionano Science and Technology , Harvard University , Cambridge , Massachusetts 02138 , United States.
ACS Appl Mater Interfaces. 2018 Jul 11;10(27):23406-23413. doi: 10.1021/acsami.8b04916. Epub 2018 Jun 29.
Buckling instabilities-such as wrinkling and creasing-of micropatterned elastic surfaces play important roles in applications, including flexible electronics and microfluidics. In many cases, the spatial dimensions associated with the imposed pattern can compete with the natural length scale of the surface instabilities (e.g., the wrinkle wavelength), leading to a rich array of surface buckling behaviors. In this paper, we consider elastic bilayers consisting of a spatially patterned stiff film supported on a continuous and planar soft substrate. Through a combination of experimental and computational analyses, we find that three surface instability modes-wrinkling, Euler buckling, and rigid rotation-are observed for the stiff material patterns, depending on the in-plane dimensions of the film compared to the natural wrinkle wavelength, while the intervening soft regions undergo a creasing instability. The interplay between these instabilities leads to a variety of surface structures as a function of the pattern geometry and applied compressive strain, in many cases yielding contact between neighboring stiff material elements because of the formation of creases in the gaps between them.
微图案弹性表面的屈曲失稳（如褶皱和起皱）在包括柔性电子和微流控在内的应用中起着重要作用。在许多情况下，与所施加的图案相关的空间尺寸可以与表面失稳的固有长度尺度（例如，褶皱波长）相竞争，从而导致丰富的表面屈曲行为。在本文中，我们考虑由空间图案化的硬膜支撑在连续和平面软基底上的弹性双层。通过实验和计算分析的结合，我们发现三种表面不稳定性模式——褶皱、欧拉屈曲和刚体旋转——对于硬材料图案是观察到的，这取决于与自然褶皱波长相比的膜的面内尺寸，而中间的软区域则发生起皱不稳定性。这些不稳定性之间的相互作用导致了各种表面结构作为图案几何形状和施加的压缩应变的函数，在许多情况下，由于它们之间的间隙中的褶皱的形成，导致相邻的硬材料元件之间的接触。
