Flexural properties of E glass and TR50S carbon fibre reinforced epoxy hybrid composites

Abstract

A study on the flexural properties of E glass and TR50S carbon fibre reinforced hybrid composites is presented in this paper. Specimens were made by the hand lay-up process in an intra-ply configuration with varying degrees of glass fibres added to the surface of a carbon laminate. These specimens were then tested in the three point bend configuration in accordance with ASTM D790-07 at three span-to-depth ratios: 16, 32 and 64. The failure modes were examined under an optical microscope. The flexural behaviour was also simulated by finite element analysis, and the flexural modulus, flexural strength and strain to failure were calculated.It is shown that although span-to-depth ratio shows an influence on the stress-strain relationship, it has no effect on the failure mode. The majority of specimens failed by either in-plane or out-of-plane local buckling followed by kinking and splitting at the compressive GFRP side and matrix cracking combined with fibre breakage at the CFRP tensile face. It is shown that positive hybrid effects exist for the flexural strengths of most of the hybrid configurations. The hybrid effect is noted to be more obvious when the hybrid ratio is small, which may be attributed to the relative position of the GFRP layer(s) with respect to the neutral plane. In contrast to this, flexural modulus seems to obey the rule of mixtures equation.