An experimental investigation on high velocity impact behavior of hygrothermal aged CFRP composites

In order to obtain the effect of hygrothermal aging on the high speed impact resistance of carbon fiber reinforced composites (CFRP), ballistic impact tests using flat blades projectile were conducted on the T700/TDE-85 laminates subjected to artificial accelerated hygrothermal aging (70 degrees C, RH95%) for different durations. Short beam shear tests were conducted on the aged specimens to evaluate the interfacial properties degradation. The effect of hygrothermal aging on the energy absorption and ballistic limit of composites were discussed. It is shown that the moisture absorption rate of the composites is in agreement with Fick law, with an equilibrium moisture absorption rate of 0.74% at 1369 h. The interlaminar shear strength (ILSS) descends rapidly with aging time and the retention rate of interlaminar shear strength was 50.6% after 2000 h. The ballistic limit and the critical energy absorption of the composites declined notably with the increase of aging time. Due to the weakened fiber/matrix interface, the delamination failure area in rhombic shape is of increasing severity with aging time. The matrix cracking and fiber/matrix interface debond due to long-term exposure to hygrothermal environment reduce the high velocity impact resistance of the composites.