Delamination buckling of stitched laminates

Delamination buckling of stitched laminates can cause high interlaminar stresses which, in turn, lead to delamination growth. This study presents a three-dimensional model for the analysis of local buckling of stitched composite laminates with an embedded elliptical delamination near the surface. Effects of stitching, delamination sizes, delamination orientation, and stacking sequence on buckling strains are investigated by the Rayleigh–Ritz energy method. The results show that stitching has a significant effect on buckling strains and buckling mode. Buckling strains obviously increase with increase in the equivalent spring constant, k, of the stitching thread, but decrease gradually in amplitude as the delamination sizes increase. In addition, the delamination orientation and stacking sequence simultaneously affect the buckling strain.