Extremely Sharp Bending and Recoverability of Nanoscale Plates with Honeycomb Corrugation

We investigate "sharp bending" -localized, extreme bending deformation of corrugated nanoscale plates as well as their ability to fully recover from such bending. Unlike planar films, these mechanical metamaterials with nanoscale thickness exhibit surprising mechanical robustness and recoverability due to their periodic honeycomb corrugation and high aspect ratios (e.g., height-to-thickness ratio). An analytical model that fully characterizes one-dimensional bending of these corrugated plates at large deformations is developed and validated by comparing the predictions to experimental and finite element results. The sharp bending is enabled by a nonmonotonic moment-curvature relation that allows for the coexistence of regions of high and low curvatures despite the complete linearity of the underlying material. Systematic studies are performed to investigate the effects of the corrugation geometry parameters on the sharp bending properties, identifying the parameter space where the structures exhibit complete recovery from sharp bending. Optimized plate mechanical metamaterials could be employed for applications requiring rigid lightweight plates that can recover their shape after extreme bending deformation, for example, wings of microflyers or expandable aerospace components that need to be deployed after take off.