Experimental study on the stitching reinforcement of composite laminates with a circular hole

Experimental study is carried out on the stitching reinforcement of composite laminates containing a circular hole. First, the tensile strength and stiffness are measured, and their dependence on stitching parameters such as stitching needle span, row spacing, edge distance and stitching type are analyzed. Next, the strain distribution and concentration are investigated analytically and experimentally for different stitching parameters, external load and edge location of the hole. It is shown that the results of stitching reinforcement are quite different for composite laminates with a circular hole, which could provide proper stitching parameters for designers.