Experimental and numerical investigation of Mode II fracture in fibrous reinforced composites

A straightforward procedure is described for utilizing experimentally evaluated bridging laws that characterize Mode II fracture growth of composite materials into numerical simulations. Unidirectional glass/epoxy end notch flexure (ENF) coupons have been fabricated and tested. Three data reduction schemes available in the literature were used for the construction of the R-curves together with the J-integral approach for the derivation of the bridging laws. Two traction— separation models have been utilized for the characterization of the fracture process zone (FPZ) developing during the delamination propagation process. The first model considers only the existence of a bridging zone behind the physical crack tip, whereas the proposed model considers both the existence of a bridging zone and of a cohesive zone in front of the physical crack tip. The traction—separation models were implemented into interface elements for the simulation of the ENF tests. Numerical results have shown that the proposed procedure together with the proposed traction— separation model is quite promising for simulations that involve Mode II fracture growth.