Design, manufacture and evaluation of laminated carbon/epoxy I-beams in bending

Composite I-beams of several different lengths were fabricated by using a hot press with an open mould. Several manufacturing-related issues were addressed. The bending behaviour of these I-beams was evaluated both experimentally and analytically in terms of bending stiffness, strength and manufacturing quality. A particular attention was paid to the potential change of the damage characteristics induced by a variation of the length-to-depth ratios of the beams. The manufacturing features were shown to be insensitive to the sectional flexural modulus and the latter was in good agreement with the predicted. The sectional shear modulus could not be properly estimated experimentally due to limited web in-plane shear. The joint reinforcement and/or segment laminate symmetry did not have the significant effect on the flexural strength due likely to the substantial laminate thickness and as well as to small length-to-depth ratios. It was shown that the ultimate failure was initiated at the bent fillet regions, which were in high local stresses. The presence of ply discontinuity could be the most significant contributing factor. Decreasing the length-to-depth ratios of the beams led to the change of the damage mechanisms from flexural failure to flange delamination. It was demonstrated that the present manufacturing method is viable for fabricating composite I-beams of a good quality and that an established analytical methodology is useful for further bending investigations of I-sections through cross-sectional dimension and lay-up designs.