Inter-Laminar Strength of Bonded Composite Lap Joints with Selective Stitching through the Thickness

In bonded composite lap joints, inter-laminar strength is critical to prevent the delamination. In this paper, the phenomenon of progressive delamination in lap joints is simulated in ABAQUS software using stress based composite failure model. It is observed that in all the joints, failure initiation is due to high inter-laminar stresses at the edges of the lap joint. Use of through the thickness stitching results in a significant improvement in inter-laminar strength in joints. These joints are further analyzed for “selective stitching” wherein the stitching is restricted to the failure regions. The results show that selective stitching is able to provide failure strengths close to that of fully stitched model.