To realize three-dimensional (3-D) simulation of weft-knitted fabrics, this paper proposes a 3-D loop modeling method which includes yarn texture and rapid deformation of fabric. The deformation of the fabric is achieved using a simplified particle system. In this study, the shape of the loop is controlled by using 10 control points, and the coordinates of the loop type control points are calculated in combination with the actual loop shape and a quadratic Bezier curve equation. To realize the deformation of the loop, the relationship between the control points and the particle system is established. The 3-D surface model of the yarn is constructed based on a local frame of the loop path. In addition, the yarn simulation is achieved by texture mapping. The simulation of fancy weft-knitted fabric is realized by the joint programming of Visual Studio and OpenGL. The results show that the simplified particle model can accurately achieve the deformation of the fabric with high efficiency. The geometric model properly represents the loop shape and exhibits the yarn texture.

In this paper, a novel auxetic weft-knitted fabric was firstly designed, which was based on the rhombus-shaped grid re-entrant structure. Then the fabric was fabricated using Kevlar filament yarn with 200D fineness on a computerized flat knitting machine. And the Poisson’s ratio values in weft, warp, and diagonal directions of this weft-knitted fabric were measured. The results showed that it exhibits the negative Poisson’s ratio effect in all three directions. Then the quasi-static stab resistance tests at five different puncture speeds were carried out on this auxetic weft-knitted fabric and the plain weft-knitted fabric with same raw material and similar loop length. The experimental results show that the auxetic weft-knitted fabric has higher peak load and energy absorption capacity at quasi-static loading. The results also show that the quasi-static stab resistance of the auxetic weft-knitted fabric strengthens with the increase of the puncture speed, but changes little after the puncture speed reaches a certain value (50 mm/min).

Auxetic warp-knitted spacer fabrics have gained increasing interest due to their excellent properties, such as shear resistance, indentation resistance, synclastic curvature and so on. Soft composites made from auxetic warp-knitted spacer fabrics and A/B two-component silicone rubbers were studied in this paper. The stabbing resistance of composites made by different auxetic fabrics (Fabrics 1–4#) and at different filling rates (0%, 20%, 40%, 70%, 100%), respectively, were tested using a universal Material Testing System. The results show that the peak load, energy absorption and deformation displacement of the composites increase with an increase of auxetic performance and filling rate. In addition, a better auxetic effect and larger filling rate can result in less damage. The composites with a higher filling rate are more like an elastomer. The auxetic effect also has an important role in stabbing resistance, which is due to fabrics with a larger negative Poisson's ratio value having a denser face layer structure and more deformable units, which can lead to better stabbing resistance for the composites.

No abstract

No abstract