Development of a textile structure for multi-directional auxetic deformation

Previous studies of auxetic composites reinforced with woven fiber structures focused on unidirectional tension or compression. Multiple fibers are often required to play different roles in the structure, making it difficult to fully exploit the advantages of auxetic materials in real-world applications. Here, a single fiber-composed textile structure that can be stretched in various directions to produce auxetic behavior was developed. The single-layer structure was successfully fabricated using a three-dimensional (3D) printing method and evaluated by finite element analysis (FEA). The tensile deformation behavior of the 3D structure was simulated, and Poisson's ratio (PR) values of the single-layer and 3D structures were obtained. There was good agreement between the FEA and experimental results, and the proposed structure can exhibit auxetic behavior when stretched in three orthogonal directions. With tensile displacements of 4 mm in the X and Z directions, the 3D structure was able to achieve maximum negative Poisson's ratio (NPR) values of −0.26 and −0.43, respectively. In particular, the diameter ratio of the fibers in each direction is an influential factor in terms of the degree of auxetic deformation of the textile. Thus, the results of this study could inform the development of novel multi-directional auxetic textile composites.