Effects of z-pinning on Mode I dynamic delamination of woven composite laminate

The dynamic Mode I delamination initiation in a z-pinned woven composite laminate is studied using a Wedge Insertion Fracture method on a Kolsky Bar apparatus. The crack initiation was monitored using crack detection gauges and high-speed imaging. It is determined that fracture initiated near the peak load recorded in the transmission bar at all loading rates covered in this study. Comparison of load at fracture initiation with loading rate shows that as loading rate increases, the load at fracture initiation also rises for all pin diameters tested. The data also suggest that load at fracture initiation rises with pin density. It is also demonstrated that laminates containing z-pins have a higher dynamic fracture initiation load than those without at comparable loading rates.