Simulating Compliant Crease Origami With a Bar and Hinge Model

Small-scale origami inspired assemblages are usually made with soft compliant plates to serve as creases because it is difficult to fabricate real hinges at those scales. In most conventional origami modeling techniques, these soft and compliant creases are usually neglected and simplified as concentrated rotational springs. Such simplification does not capture the three dimensional geometry correctly and also neglects torsional and extensional deformations of the compliant creases. These deformations could be significant for determining advanced mechanical behaviors of the origami such as bistablity and multistablity. In this paper an improved formulation of a simple bar and hinge model is proposed to capture the geometry and flexibility of compliant creases. Equations for assigning bar areas and spring stiffness are derived based on the theoretical plane stress plate models and the pseudo-rigid model. These equations are next verified against finite element simulations for both infinitesimal stiffness and large deformation stiffness. It is found that the proposed model can predict stiffness characteristics of compliant crease origami relatively well. Furthermore, two examples are used to demonstrate the efficiency and capability of the proposed model.