Delamination in asymmetrically tapered composites loaded in tension

摘要

Tapered 0/ ± 45° carbon fibre-epoxy specimens with one flat surface were tested in tension. Results were obtained for tapered specimens of similar geometry with 0/ ± 45° and with only ±45° discontinuous plies. Tests were also carried out on specimens with plies cut to produce similar discontinuities, but with ±45° fill-in plies to eliminate the tapered geometry. Specimens with discontinuous 0° plies delaminated into the thick section, with very similar results for tapered and untapered geometry. Good predictions of delamination load were obtained with an equation previously developed for symmetric specimens based on the strain energy release rate associated with the discontinuous plies. The asymmetry does not appear to be a critical factor for this type of delamination. Tapered specimens delaminated into the thin section at lower loads, with the layup of the discontinuous plies having little effect on the behaviour. The driving mechanism is believed to be the straightening out of the outer plies due to the geometry of the taper, with the asymmetry of the specimens having only an indirect effect.