Auxeticity from the Folded Geometry: A Numerical Study

The folded geometry has successfully been transformed into auxetic woven fabric in the literature. However, the influences of the microgeometric parameters on the macroscopic behavior have not been addressed yet. Herein, several key microgeometric parameters for the folded geometry are identified and the mechanical behaviors of the folded structure are preliminarily studied using the finite element method. The results show that the folded structure can be unfolded in both longitudinal and transverse directions when stretched and thus achieve a negative Poisson's ratio. More interestingly, another fantastic property of tension-bending coupling effect is found in the folded structure and a competition exists between the auxeticity and the tension-bending coupling effect. This is the first time to report a structure that can stimulatingly have the auxeticity and the tension-bending coupling effect. Due to the unique properties, the folded geometry is very promising in some important fields; for example, the textiles, civil engineering, and auto industry. The present work may provide a good guide for the design and application of the folded structure.