Stab-resistance of auxetic weft-knitted fabric with Kevlar fibers at quasi-static loading

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).