Paper number 161

INFLUENCE OF FIBRE CROSS-SECTIONAL ASPECT RATIO ON MECHANICAL PROPERTIES OF GLASS FIBRE/EPOXY COMPOSITES

Lin Ye and Shiqiang Deng

Centre for Advanced Materials Technology
Department of Mechanical and Mechatronic Engineering
University of Sydney, NSW 2006, Australia

Summary

A comprehensive experimental study was conducted to identify effects of the fibre cross-sectional aspect ratio on mechanical properties as well as failure modes of glass-fibre/epoxy composites using fibres of three different cross-sectional shapes (round, peanut-shaped and oval). It was found that the fibres of peanut and oval cross-sectional shapes tend to align with the long axis of the cross section perpendicular to the direction of the applied pressure or in the plane of a composite laminate. As a result, many fibres were overlapped with each other, having large contact areas, which act as a path for longitudinal crack propagation. For the composites with fibres of large cross-sectional aspect ratios, a cumulative damage progression with a high failure strain was observed for the tensile and flexure tests in the longitudinal direction. However, the longitudinal tensile modulus and strength were nearly the same for the three composite systems. The transverse strength and strain-to-failure for transverse tensile and flexural tests showed the similar case as those in longitudinal tension and flexure, but the transverse moduli were reduced for composites with fibres of large aspect ratios. A low delamination resistance was also observed for such composite systems reinforced by glass fibres with large fibre cross-sectional aspect ratios, which is attributed to the effect of fibre over-lapping in these composites.

Keywords

glass-fibre/epoxy composites, fibre cross-sectional aspect ratio, fibre-matrix interface, mechanical properties.