Light-induced wrinkling instability of confined annulus liquid crystal elastomer film

Authors of previous studies have focused on wrinkling phenomena in thin films with relatively large stiffness under mechanical loadings. A liquid crystal elastomer (LCE) is a smart soft material sensitive to various environmental stimuli. In this letter, we investigate the wrinkling instability of a confined LCE film with different inner hole sizes induced by light illumination. The LCE film is clamped at the outer edge and has a free inner edge. Based on linear perturbation analysis, we obtain the critical condition for the onset of wrinkling instability. Whether the film will remain flat or bifurcate into a wrinkled state is determined by the value of expansion coefficient, light intensity, inner hole size, and thickness of the LCE film. We find that a film with a bigger inner hole size corresponds to a large wrinkle number and show that the expansion coefficient of a LCE and light intensity can be used to adjust the wrinkling instability behavior and time consumption for the appearance of wrinkles.