A semi-empirical model to predict the low-velocity impact behavior of weft-knitted spacer fabrics reinforced composites

Using fabrics as reinforcement of composites considerably leads to improve some of mechanical properties. One of the important mechanical properties is resistance to impact forces. Therefore, in the present study, the impact behavior of composites reinforced with weft-knitted spacer fabrics has been studied. Due to the out of plane nature of impact force , the through-the-thickness reinforcement of composite play a key rule in undergoing the impact forces. Weft-knitted spacer fabrics are adequate structures to reinforce through-the thickness of composite due to the existence of spacer yarns. In this study, at first, principle of low velocity impact behavior of composites was studied. Then, a semi-empirical model was generated to predict the impact behavior of composites considering the structural parameters of weft-knitted spacer fabrics as reinforcement of composites. In order to validate the proposed model, weft-knitted spacer fabrics with different types of spacer yarn's orientation were produced and used as reinforcement of composites. The low-velocity impact test was carried out on the prepared samples. A good correlation was found between theoretical and experimental results.