THE FATIGUE PROPERTIES OF WEFT-KNIT FABRIC REINFORCED EPOXY-RESIN COMPOSITES

Carbon and glass tows were fabricated into Interlock, Full-Cardigan, Milano and Rib fabric stitches by weft-knitting. The fatigue strength of composites made from these fabrics and epoxy resin was studied in terms of the relationship of the knitting stitch and the applied direction, the stress number of the fatigue distribution, hysteresis heating, lost strength, and fatigue damage propagation rate. In addition, by using the above composites, we compared the fatigue strength with plain-weave fabric composites. The weft-knit composites loaded by fixed cantilever bending showed that the wale direction had a greater stiffness than the course direction. The Interlock fabric composite provides the highest fatigue resistance in these weft-knit stitches. However, the fatigue strength of a plain-weave fabric composite is higher than that of the weft-knit fabric composites. In a fatigue test, the hysteresis heating is below 60-degrees-C. On the other hand, the fatigue resistance ability can be increased about 40-60% by a sandwich lamination method.