In this paper, the pull-out characteristics of composite Z-pins with various groove shapes was investigated. The groove shape of composite Z-pins was made by applying temperature and pressure to the top and bottom of laminated composites inside the autoclave. Then, the dumbbell type of pull-out test specimen was made by applying adhesive bond. Six types of pull-out test specimens were fabricated by changing the groove length. Pull-out load and displacement sere observed for those specimens with different groove ratio. The results show that the maximum pull-out load of the grooved pin with grooved ratio 0.4 was increased up to 30.6% by comparing the plain pin. The grooved pin has a high pull-out resistance even after the fracture of the interface.

In this study, carbon fiber Z-pins were fabricated by applying the different manufacturing process, and pull out test was performed for the dumbbell type of test specimens. Carbon fiber Z pins with smooth surface(type I) and stepped surface(type II, type III) were fabricated by using autoclave. Carbon fiber Z-pins with stepped surface were manufacturing method, that is, mold forming and machining process. The experimantal results show that carbon fiber Z pins have superior pull-out characteristics to carbon steel Z-pins. Pull-out load and pull-out toughness of carbon fiber Z pins with stepped surface are larger than those of carbon fiber Z-pins with smooth surface. Pull-out load and pull out toughness of mold f ormed Z-pin are 31% and 218% larger than those of smooth surfaced Z-pins, respectively.