Engineering Tunable, Multifunctional Composites Inspired By Paper Art

Current research efforts in combining elasticity and multifunctionality have focused primarily on the atomic, molecular, and nanoscale structural elements of these materials. Drawing inspiration from paper art, we present a new framework to engineer composites in which the third dimension is coupled to functionality. Here we look into controlling defects, borrowing concepts from kirigami, a Japanese paper cutting technique. We carry out a systematic study of the mechanical response of assembled nanocomposite sheets patterned with periodic arrays of cuts guiding stress concentration and distribution. We show that finite element analysis can predict the mechanism underlying this strain response and show that stress is delocalized around the cut defects, where unpredictable local failure is prevented and ultimate strain increased to >300%. We show that kirigami can enable the fabrication of highly elastic composites that remain conductive at high strains. Finally, we establish a systematic framework to predictively control mechanical properties by geometrical design.