Surface modification of carbon fiber/epoxy composites with randomly oriented aramid fiber felt for adhesion strength enhancement

To increase the strength of an adhesive joint whose adherend is composed of a carbon fiber/epoxy composite, the surface of the adherend is reinforced with randomly oriented aramid fiber felt before the full cure of the adherend. With this smart cure cycle, the aramid fibers are exposed from the adherend, promoting a bridging effect between the fibers and the adhesive. The cured carbon fiber/epoxy composite material, on which the aramid fiber felt is placed, is co-cure bonded with a smart cure cycle developed in this work. The improvement of the adhesive bonding strength due to the aramid fiber felt is measured with the single-lap shear test of adhesively bonded joints. Additionally, the flexural strength of the carbon fiber/epoxy composite adherend with the co-cure bonded aramid fiber felt is measured.