  A series of experimental results on the in-plane fracture of a fiber
reinforced laminated composite panel is analyzed using the variational
multi-scale cohesive method (VMCM). The VMCM results demonstrate the influence
of specimen geometry and load distribution on the propagation of large scale
bridging cracks in the fiber reinforced panel. Experimentally observed
variation in fracture resistance is substantiated numerically by comparing the
experimental and VMCM load-displacement responses of geometrically scaled
single edge-notch three point bend (SETB) specimens. The results elucidate the
size dependence of the traction-separation relationship for this class of
materials even in moderately large specimens, contrary to the conventional
understanding of it being a material property. The existence of a "free
bridging zone" (different from the conventional "full bridging zone") is
recognized, and its influence on the evolving fracture resistance is discussed.
The numerical simulations and ensuing bridging zone evolution analysis
demonstrates the versatility of VMCM in objectively simulating progressive
crack propagation, compared against conventional numerical schemes like
traditional cohesive zone modeling, which require a priori knowledge of the
crack path.
