Characterization and modeling of the tensile properties of plain weft-knit fabric-reinforced composites

Abstract

This paper describes analytical models for predicting tensile properties of knitted fabric-reinforced composites. Initially, tensile properties of plain weft-knit glass-fiber fabric-reinforced epoxy composites were determined experimentally in the wale and course directions. Elastic properties were predicted by using a 'cross-over model' and laminated plate theory. The analytical model expresses the crossing over of looped yarns of knitted fabric, and fiber- and resin-rich regions of composite. Elastic properties of the composite were determined by combining the effective elastic properties of looped yarns and resin-rich regions. Study of tensile failure mechanisms indicated that ultimate failure of a knitted-fabric composite occurs upon the fracture of yarns bridging the fracture plane. Tensile strengths were predicted by estimating the fracture strength of bridging yarns. Tensile properties of knitted-fabric composites with different volume fractions of fibers were predicted. Analytical procedures have been validated by comparing predictions with the experimental results. The applicability and limitation of these models have been discussed. © 1997 Elsevier Science Limited.