2020 Volume 5 Pages 116-121
The purpose of this research was to investigate the effect of ultrasonic needle punching on interlaminar strength and fracture toughness of unidirectional carbon fiber reinforced thermo-plastics. The ultrasonic needle punching process was conducted with four stabbing speeds and three stabbing densities. The results of the interlaminar tensile test showed slight improvement in interlaminar tensile strength when the needle was stabbed at higher speed. In addition, when the direction of the fiber on the bonding surfaces facing each other was the same, the interlaminar tensile strength was improved compared with the case where the fiber directions were different. The results of the double cantilever beam test showed that the Mode I interlaminar fracture toughness improved when the stabbing density was low or the needle was stabbed at high speed. In addition, the amount of load decreasing at the time of crack propagation decreased when the needle was stabbed at high speed.
