On the symmetries of the origami waterbomb pattern: kinematics and mechanical investigations

Origamis are becoming the inspiration of new adaptive structures applied for several purposes. One of the challenges of the design of the origami inspired structures is to deal with the large number of variables and degrees of freedom (DoFs) associated with such complex structures. Closed tessellations have a reduced number of DoF when compared to the opened ones. Besides, the coupling due to the closure of the tessellation promotes some periodicity along the structure. Symmetric behaviors allow the description of the structure from a unit cell behavior, establishing reduced-order models. This paper investigates the origami waterbomb pattern, exploring the unit cell behavior and its symmetries. Initially, kinematics analysis based on an equivalent mechanism approach establishes a reduced-order model associated with symmetry hypotheses. Afterward, mechanical analysis is investigated using a nonlinear finite element analysis through bar-and-hinge formulation. A comparison between both formulations is performed showing the range of validity of the reduced-order model description. The general conclusions are applied to a cylindrical tessellation under symmetric actuation showing the capability of the reduced-order model for the origami description. Results show that the rigid foldability hypothesis is the essential point for the equivalence between the two descriptions.

Automated summary

This paper investigates the unit cell behavior and symmetries of the origami waterbomb pattern, establishing a reduced-order model based on an equivalent mechanism approach for kinematics analysis and using nonlinear finite element analysis for mechanical analysis. The results show that the rigid foldability hypothesis is crucial for the equivalence between the two descriptions.