Mechanical instability driven pattern formation

Subject to external stresses or stimuli, materials may undergo mechanical instabilities of diverse type. Such deformations are ubiquitous, especially in soft materials or geometrically thin structures like plate and shell. In our group, various intriguing patterns induced by mechanical instabilities are fabricated in various system such as (a) bendable elastomer, (b) metal/polymer bilayer and (c) hydrogel micro structures.

Among these pattern/structure formation, our research is particularly focused on out of plane deformation such as wrinkles, ridges and folds. Wrinkles are periodic pattern with uniform wavelength, and can be transformed into ridge or fold as stress becomes localized. Since characteristic lengths of these patterns like wavelength of the wrinkle are determined by an energy balance, we employ scaling analysis and finite element analysis (FEA) for a theoretical study. 

In the typical engineering field, mechanical instabilities used to be thought as a failure mode. However, we consider the potential of various applications of mechanical instability driven pattern formation. It can be exploited the field of (a) optics, (b) microfluidics, (c) shock absorbing media and (d) fabrication of Janus particles.