Mechanical properties of glass composites based on knitted preforms with inlays

Abstract

An attempt has been made to improve the mechanical properties of the composites with knitted preforms by introducing horizontal strands in the course direction in a flat-bed knitting machine. Flat knitted preforms were produced with different proportions of axial inlay strands and the composite laminates were prepared using the vacuum-assisted resin transfer moulding technique. It is observed that the introduction of inlay strands influences the structure of the knitted preform by increasing course density, wale density and thickness. This result in the increased anisotropic behaviour of the composite laminate showing increased strength in the course direction and decreased strength in the wale direction. The

flexural strength of the knitted preform composites increases in both wale and course directions with the introduction of inlay strands. Laminates from preforms with two inlays exhibit overall improved impact properties whereas those from preforms with one inlay show higher impact damage tolerance index. These observations are explained in terms of the change in fibre architecture brought about by the introduction of the inlay strands.