Fracture resistance of graphene origami under nanoindentation

Graphene has received extensive research interest from both scientific and technological communities due to its excellent physical properties. However, owing to its two-dimensional structure, graphene experiences brittle fracture under external loading, which limits its application as reinforcing fillers in composites. In this study, we apply an origami technique to improve the flexibility of graphene under nanoindentation. Based on intensive molecular dynamics simulation, we found that graphene origami (GOri) can withstand loads and indentation depths up to 37% and 138% greater, respectively, than pristine graphene. The flexibility and strength of GOri can be further enhanced in the bilayer format by adding one pristine graphene or one identical GOri. The maximum indentation loads of the bilayer model are at least 60% higher than that of its single-layer counterpart. Though Young's modulus remains unchanged, the bending stiffness is improved remarkably due to the auxeticity of GOri. The study provides significant insights into the failure mechanisms and mechanical properties of GOri and offers practical design guidelines for graphene-based impact protection applications.