Sheet forming simulation of knitted fabric composites considering fabric reorientation

Abstract

A study was carried out to obtain the stress-strain relationship for large deformation in a knitted fabric composite. For this purpose, the Kevlar fiber modulus was taken from standard handbook while that of polypropylene (PP) matrix was averaged from a Dynamic Mechanical Analyzer (DMA) between room temperature and the melting point. A negative thickness strain that implies thinning was observed. This effect was attributed to draw-out. Positive thickness strain that indicated the occurrence of thickening due to circumferential contraction was found at the sheet periphery.