The tensile properties of weft-knitted biaxial tubular fabrics and reinforced composites

Weft-knitted biaxial tubular (WKBT) fabrics have been infiltrated via a resin film infusion technique to fabricate reinforced composites. To understand the mechanical properties of WKBT fabrics and the reinforced composites, the strength efficiency of insertion yarns and insertion fiber volume fraction are used to evaluate the tensile strength. The tensile properties of WKBT fabrics and the reinforced composites are studied in the 0° and 90° directions. The results show that both have two failure stages. The first stage is the fracture of insertion yarns which provide the main tensile strength, and the second stage is the fracture of stitch yarns which have significant effect on the tensile strength of WKBT fabrics and the reinforced composites. It is observed that the deformation behavior and failure mechanism of WKBT fabric reinforced composites are closely related to the structure of WKBT fabric, which can be used to predict the failure mode and morphology of WKBT fabric reinforced composites.