Nesting effect on the mode II fracture toughness of woven laminates

The mode II fracture toughness is evaluated for carbon fibre T700-epoxy reinforced woven laminates using the end notch flexure set-up. The analysed woven composites have a different tow size (3K/12K). Three different nesting/shifting configurations are applied to the plies at the fracture surface. Corrected Beam Theory with effective crack length method (CBTE) and Beam Theory including Bending rotations effects method (BTBE) are evaluated for obtaining mode II fracture toughness. During data post-processing, the importance of the bending angle of rotation and the test configuration is observed to be important. The results show that crack propagation under mode II is more stable if the matrix is evenly distributed on the surface. The nesting does not significantly affect mode II fracture toughness values, although a greater presence of matrix on the delaminated area increases its value.