Effects of gamma ray irradiation on penetration hole in and fragment size from carbon fiber reinforced composite plates in hypervelocity impacts

This study examines how gamma ray irradiation affects the penetration holes in and fragment sizes from carbon fiber reinforced plastic (CFRP) plates due to hypervelocity impacts. In order to do so, quasi-isotropic CFRP plates made of unidirectional pre-impregnated sheets and 1-mm-diameter spherical projectiles made of aluminum alloy (2017-T4) were used. Witness plates (200 mm × 200 mm × 2 mm) made of copper (C1100P-1/4H) and containing a 30-mm-diameter hole were placed 50 mm in front of and behind each target to examine the fragments based on ISO 11227. The fragments collected from the impact and rear sides of the target were compared. Gamma ray irradiation had a slight effect on the penetration hole, the fragment size distributions, and the craters on the witness plates. When the gamma ray irradiation was 10 MGy, the penetration holes at impact velocities of 2.4 km/s and 5.3 km/s became slightly smaller. At the impact velocity of 2.4 km/s, perforation of the 0.5 MGy, 6.5 MGy, and 10 MGy specimens prevented the projectile from fracturing.