Ply fragmentation in unidirectional hybrid composites linked to stochastic fibre behaviour: A dual-scale model

Abstract Ply fragmentation is a dual-scale phenomenon comprised of fibre breaks at the micro-level and ply fractures at the meso-level. A dual-scale stochastic model is proposed to predict the longitudinal tensile behaviour of unidirectional interply fibre-hybrid composites, including ply fragmentation in low elongation (LE) plies. The predictions of the stress-strain diagram are validated for carbon/glass hybrid composites and agree well with experimental results. A parametric study was performed where the Weibull scale parameter of the high elongation (HE) fibres and shape parameter of the LE fibres were varied. The Weibull scale parameter of the HE fibres strongly influences the failure mode of the hybrid composite. An LE fibre type with a low Weibull modulus should be used if a composite with a smooth stress-strain diagram is desirable. The model presented can be used for any layup and material configuration, contributing to a more intelligent and efficient design of hybrid composites.