Analytical modelling of pseudo-ductility in angle-ply CFRP laminates with central unidirectional plies

A new analytical modelling method is developed and subsequently used to predict the pseudo-ductile, metal-like stress-strain responses of thin ply CFRP [±θ=0]s laminates. Three combinations of thin ply materials containing standard (235 GPa) and high (540 GPa, 720 GPa, 780 GPa) modulus fibres have been utilised. The modelling method is used to determine the range of ±θ values for each material combination that will exhibit pseudo-ductility. It is shown that a high modulus 0º ply and standard modulus ±θ layers can produce considerable pseudo-ductility, via fragmentation of the 0º ply and local delaminations at the 0/-θ interfaces. With the use of the various thin ply materials and a range of ±θ angles between 20º–30º, the stress-strain response of these laminates can be finely controlled to achieve a desired ‘yield’ stress plateau, pseudo-ductile strain or laminate strength.