Anisotropic behaviour of knitted glass fibre/epoxy composites under compressive and shear loading

Abstract

The authors have investigated the anisotropic properties of plain weft knitted glass fibre fabric reinforced epoxy composites oriented at different off-axial angles and subjected to compressive and shear loads. The compression test results in the off-axial angles of 0°, 30°, 45°, 60° and 90° indicated that the ultimate compressive strength and compressive modulus were greatest at 0° but decreased at other off-axial angles. The compressive strength was higher than the tensile strength for the knitted fabric composite at any off-axial angle. On the other hand, the shear test results for the same off-axial angles showed that the ultimate shear strength and shear modulus were greatest at the off-axial angle of 60°. A simple analytical model was applied to calculate the compressive strength at any off-axial angle, by using three critical strength parameters, i.e. the compressive strengths of 0° and 90° and the shear strength of 0°. The theoretical strength data agree favourably with our experiments.