Abstract: Due to the low interlaminar strength of traditional composite laminates, stitching technology has been widely used to improve their interlaminar properties. In order to study the mode Ⅰ delamination performance of the stitched composite laminates, the double cantilever beam (DCB) model was used to calculate the mode Ⅰ delamination failure load. Then the effects of different stitch density and diameter for the interlaminar failure load of the composite laminates were discussed. The result show that the stitching technology can hinder the delamination propagation for the composite laminates model. The delamination front in the stitched composite laminates model is a wavy line, while the delamination front of the unstitched composite laminates model is a straight line. The increase of stitch density will improve the interlaminar failure load of the composite laminates model. Compared with the unstitched composite laminates model, the interlaminar failure load of the model with stitch density of 10 mm×10 mm, 7.5 mm×7.5 mm, 5 mm×5 mm and 2.5 mm×2.5 mm increases by about 7 times, 9 times, 10 times and 15 times, respectively. The increase of the stitch diameter will also improve the interlaminar failure load of the composite laminates model. The maximum interlaminar failure load of the model with the stitch diameter of 1 000 Dan and 2 000 Dan is about 1.5 times and 2 times that of the model with the stitch diameter of 500 Dan, respectively.

Key words: stitching, composties, interlaminar property, cohesive zone model