Origami-inspired auxetic structures: Design and performance in quasi-static and dynamic loading

Auxetic metamaterials have gained attention due to their unique mechanical properties. Integrating origami structures with cellular structures can significantly enhance their energy absorption capacity under mechanical loads. This study develops a novel auxetic structure by combining a curved origami design with the cross-petal auxetic structure. The structure's behavior under in-plane compressive loading is analyzed using finite element simulations and validated through experimental testing of 3D-printed specimens. The effects of loading rates (quasi-static, low-, medium-, and high-velocity) and geometrical parameters on energy absorption are examined through parametric studies. Structure grading, based on unit cell wall thickness, is also investigated to enhance performance. Finally, the proposed structure's energy absorption is compared with two common auxetic metamaterials (reentrant and chiral) under various loading conditions. Results indicate deformation becomes more localized with increased loading velocity, with the proposed design achieving a 70% improvement in energy absorption over non-origami designs and a 16% enhancement through grading. The main contribution of this study is the creation of a hybrid structure combining curved origami and cross-petal auxetic designs, achieving a 70% improvement in energy absorption. The dual plateau stress region and graded design further enhance performance, positioning it as an innovative solution for impact protection and soft robotics. The proposed structure exhibits up to 7.56 times higher specific energy absorption under quasi-static loading compared to reentrant and chiral designs, maintaining superior performance at higher loading velocities.