INTERFACIAL EVALUATION OF UD-CFRP BY THERMAL AGING VIA ACOUSTIC EMISSION, ELECTRICAL RESISTANCE AND THERMOGRAM METHOD

Interfacial and mechanical properties of thermal aged carbon fiber reinforced epoxy composites (CFRP) were evaluated using acoustic emission (AE), electrical resistance (ER) and thermogram measurements. Unidirectional (UD)-composites were aged at different temperatures to produce different interfacial conditions. AE and ER of UD composites were measured along 0, 30, 60 and 90o. Changes in wavespeed, with thermal aging, were calculated using wave travel time from AE source to AE sensor and the changes in ER were measured. For thermogram evaluation, the composites were laid upon on a hotplate and the increase in the surface temperature was measured. Static contact angle were measured after different thermal aging and elapsed times to evaluate wettability. Interlaminar shear strength (ILSS) and tensile strength tests were also performed to explore the effects of thermal aging on mechanical properties. While thermal aging was found to affect all these properties, the changes were particularly evident at 400 degrees C.