The influence of target geometry on the high velocity impact response of CFRP

Abstract

The influence of geometrical parameters on the high velocity impact response of CFRP has been studied. Impact velocities between 10 m/s and 500 m/s were obtained using a high pressure nitrogen gas gun. The resulting impact damage was assessed visually, by optical microscopy and by thermally deplying specimens in an oven at 420°C. It has been shown that increasing the flexural stiffness of a target by varying the fibre stacking sequence or increasing its thickness changes the mode of initial fracture from a lower surface flexural failure to a top surface contact failure. For a given incident energy, increasing the target thickness results in a lower level of damage as detected by ultrasonic inspection. Further, changing the specimen geometry in this way leads to significant increases in the perforation threshold energy. Increasing the surface area of the target by varying its length or width does not alter the amount of damage incurred under high velocity impact loading. Indeed, it appears that smallscale test coupons are fully capable of reproducing damage levels incurred by operational structures when subjected to high velocity impact by a light projectile.