Abstract:

For the purpose of constructing a 3-dimensional negative Poisson's ratio structure by adopting spacer warp knitting techniques, a simple model based on the structure of negative Poisson's ratio warp-knitted spacer hexagonal meshes was established and several samples were produced using Raschel double needle-bed warp knitting machine. The results of both mathematical modeling and experimental sampling indicate that negative Poisson's ratio performances of this structure mainly depend on the contraction distortion in initial state in three axis directions, especially in y-axis direction. When it comes to knitting parameters, including yarn fineness, machine gauge, fabric density, movement of guide bars and inclination angle of wales, all of them matter in the nerformances which is also affected by the stiffness of materials and the lodging of spacer yarns. It is also concluded that successive inlaying in the same direction of the spacer guide bar is in favor of the contraction distortion in y-axis direction, which means that negative Poisson's ratio performances can be more easily achieved in this way.

Key words: negative Poisson's ratio, warp-knitted spacer fabric, mesh structure, mathematical modeling, tensile performance