Auxetic and failure characteristics of composite stacked origami cellular materials under compression

The mechanical properties of cellular materials made by stacking layers of origami sheets could be designed over a wide range due to its rich suite of geometry parameters. However, due to the nature of high-volume fraction of air in the structure, these materials may show low stiffness and low strength. Fiber reinforced composites show both higher specific strength and specific stiffness compared with homogeneous materials such as metals and plastics. It could be expected that both the stiffness and strength of stacked origami structures can be improved by introducing fiber reinforced composites. In this investigation, hot molding process is used to produce composite fiber reinforced stacked origami structures. Composite stacked origami structures with different stacking angles and thickness of origami sheets are designed and fabricated. Finite element simulation and experimental compression tests are carried out to investigate their mechanical properties and auxetic characteristics. The effects of origami sheets thickness and stacking angles on the in-plane and out-of-plane auxetic characteristics of the structure are discussed. Finally, the failure modes of the structures during compression are analyzed, and their energy absorption capacity are compared with other honeycomb materials.