A stochastically homogenized peridynamic model for intraply fracture in fiber-reinforced composites

The quasi-static fracture behavior in the transverse cross-section of unidirectional fiber-reinforced composites (FRCs) is investigated using a new intermediately-homogenized peridynamic (IH-PD) model and a fully homogenized peridynamic (FH-PD) model. The novelty in the IH-PD model here is accounting for the topology of the fiber-phase in the transverse sample loading via a calibration to the Halpin-Tsai model. Both models, overall, capture well the measured load-displacement behavior observed experimentally for intraply fracture, without the need for an explicit representation of microstructure geometry of the FRC. The IH-PD model, however, is more accurate and produces crack path tortuosity as well as a stick-slip load-crack-opening softening curve, similar to what is observed experimentally. These benefits come from the preservation of some micro-scale heterogeneity, stochastically generated in the IH-PD model to match the composite's fiber volume fraction, while its computational cost is equivalent to that of an FH-PD model. The two models lead to dramatically different failure modes for the case of an asymmetric pre-notch: with the FH-PD model, failure always starts from the pre-notch tip, while with the IH-PD model, when the pre-notch is sufficiently far from the center, the composite is predicted to fail from the center of the sample, not from the pre-notch. Experiments that can confirm these findings are sought.