Pilot studies are conducted to characterize the macroscopic fracture resistance behavior using linear elastic fracture mechanics and attempt to quantify the fracture parameters which may govern the fracture and failure patterns of stitched warp-knit fabric composites. The stress state inthe crack tip vicinity prior to fracture initiation, characterized by critical stress intensity factor, T-stress, and the second-order term in #sigma# _y(r,0) at the onset of fracture, is evaluated numerically for three different specimen geometries: compact tension, center-cracked tension, and single-edge notched tension specimens. Using finite element analysis under the fracture initiation load, the critical stress intensity factors are calculated by the J-integral and a virtual crack closure method respectively. The T-stress and the second-order term in #sigma# _y(r,0) are derived and computed from two approaches, Betti's reciprocal theorem and J-integral method. With the limited experimental data, the results tend to show that the critical Mode-I stress intensity factor provides a satisfactory characterization of fracture initiation in this composite for a given laminate thickness, provided the failure is fiber-dominated and crack growth follows in a self-similar manner. Other fracture parameters can only demonstrate qualitative trends in describing the failure behavior at this stage.
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